Sarchielli P, Alberti A, Codini M, Floridi A, Gallai V.
oxide metabolites, prostaglandins and trigeminal vasoactive peptides in internal
jugular vein blood during spontaneous migraine attacks.
"Despite evidence emerging from the experimental
model of nitroglycerin-induced headache, the endogenous increase in nitric oxide
(NO) production during migraine attacks is only speculative. It has been hypothesized
that there is a close relationship between activation of the L-arginine/NO pathway
and production of certain vasoactive and algogenic prostaglandins during spontaneous
migraine attacks, but this suggestion also needs to be confirmed. In the present
study the levels of nitrites, the stable metabolites of NO, were determined with
high performance liquid chromatography (HPLC) in the internal jugular venous blood
of five patients affected by migraine without aura examined ictally. These samples
were taken within 30 min, 1, 2, and 4 h from the onset of the attack and at the
end of the ictal period. At the same time, the plasma levels of calcitonin gene-related
peptide (CGRP), neurokinin A (NKA), prostaglandin E2 (PGE2) and 6 keto PGF1alpha,
the stable product of PGI2, were assessed with radioimmunoassay (RIA) kits in
the same samples. The levels of the intracellular messengers, cGMP and cAMP, were
also measured with the RIA method. Nitrite, cGMP, CGRP and NKA levels reached
their highest values at the first hour, then they tended to decrease progressively
and returned, after the end of attacks, to values similar or below those detected
at the time of catheter insertion (ANOVA, statistical significance: P<0.001;
P<<0.002; P<0.002; P<0.003, respectively). PGE2 and 6 keto PGF1alpha,
as well as cAMP levels also significantly increased at the first hour but reached
a peak at the 2nd hour and remained in the same range until the 4th and 6th hours.
Then their values tended to decrease after the end of attacks, becoming lower
than those measured immediately after catheter positioning for internal jugular
venous blood drawing (ANOVA: P<0.002, P<0.004, P<0.001, respectively).
Our results support early activation of the L-arginine/NO pathway which accompanies
the release of vasoactive peptides from trigeminal endings and a late rise in
the synthesis of prostanoids with algogenic and vasoactive properties which may
intervene in maintaining the headache phase." [Abstract]
G, Zsombok T, Modos EA, Olajos S, Jakab B, Nemeth J, Szolcsanyi J, Vitrai J, Bagdy
NO-induced migraine attack: strong increase in plasma calcitonin
gene-related peptide (CGRP) concentration and negative correlation with platelet
Pain. 2003 Dec;106(3):461-70.
aim of the present study was to investigate changes in the plasma calcitonin gene-related
peptide (CGRP) concentration and platelet serotonin (5-hydroxytriptamine, 5-HT)
content during the immediate headache and the delayed genuine migraine attack
provoked by nitroglycerin. Fifteen female migraineurs (without aura) and eight
controls participated in the study. Sublingual nitroglycerin (0.5 mg) was administered.
Blood was collected from the antecubital vein four times: 60 min before and after
the nitroglycerin application, and 60 and 120 min after the beginning of the migraine
attack (mean 344 and 404 min; 12 subjects). In those subjects who had no migraine
attack (11 subjects) a similar time schedule was used. Plasma CGRP concentration
increased significantly (P<0.01) during the migraine attack and returned to
baseline after the cessation of the migraine. In addition, both change and peak,
showed significant positive correlations with migraine headache intensity (P<0.001).
However, plasma CGRP concentrations failed to change during immediate headache
and in the subjects with no migraine attack. Basal CGRP concentration was significantly
higher and platelet 5-HT content tended to be lower in subjects who experienced
a migraine attack. Platelet serotonin content decreased significantly (P<0.01)
after nitroglycerin in subjects with no migraine attack but no consistent change
was observed in patients with migraine attack. In conclusion, the fact that plasma
CGRP concentration correlates with the timing and severity of a migraine headache
suggests a direct relationship between CGRP and migraine. In contrast, serotonin
release from platelets does not provoke migraine, it may even counteract the headache
and the concomitant CGRP release in this model." [Abstract]
M, Alessandri M, Figini M, Geppetti P, Michelacci S.
plasma calcitonin gene-related peptide from the extracerebral circulation during
nitroglycerin-induced cluster headache attack.
"In this study, changes in plasma levels of calcitonin
gene-related peptide (CGRP) and substance P (SP) during a spontaneous-like cluster
headache attack provoked by nitroglycerin were evaluated. Peptide variations after
spontaneous or sumatriptan-induced remission were also assessed. Blood was collected
from the external jugular vein homolateral to the pain side of 30 male cluster
headache patients; 18 men were in an active and 12 in a remission one. Plasma
levels of CGRP and SP were determined using sensitive radioimmunoassays for each
peptide. CGRP-like immunoreactivity (CGRP-LI) was found to be augmented in patients
in an active period and became elevated further at the peak of the provoked attack.
A complete reversal occurred both after spontaneous and sumatriptan-induced remission.
On the contrary, nitroglycerin neither provoked a cluster headache attack nor
altered CGRP-LI in the patients in a remission period. The augmented levels of
CGRP-LI measured before and after nitroglycerin administration, when the provoked
attack reached the maximum intensity, suggest an activation of the trigeminovascular
system during the active period of cluster headache. Moreover, the clinical and
biochemical actions showed by sumatriptan stress the involvement of serotonin
in cluster headache mechanisms." [Abstract]
Fanciullacci, M Alessandri, R Sicuteri, and S Marabini
of the trigeminovascular system to nitroglycerine in cluster headache patients
Brain 120: 283-288. 1997.
"Nitroglycerine is known
to induce a headache attack in cluster headache patients, which is indistinguishable
from a spontaneous attack. It has recently been suggested that a release of calcitonin
gene-related peptide (CGRP) from peripheral terminals of trigeminal nociceptive
neurons, which supply cephalic blood vessels, underlies symptoms of cluster headache.
The aim of this study was to investigate whether the provocative action of nitroglycerine
in cluster headache is due, at least in part, to activation of the trigeminovascular
system. Nineteen subjects suffering from episodic cluster headache participated
in the study. Eleven of them were in an active period, whilst the others were
in remission at the time of the study. CGRP-like immunoreactivity (CGRP-LI) was
measured in blood samples from the extracerebral circulation before and after
the sublingual administration of nitroglycerine. Baseline CGRP-LI plasma levels
were higher (P < 0.05) in the patients who were in an active period. Only in
these patients did nitroglycerine induce an attack, which was preceded by a latent
period with a mean duration of 27 +/- 3 min. When compared with the baseline,
a significant (P < 0.01) increase in plasma CGRP-LI was detected at the peak
of the provoked attack; no such increase was detected during the latent period,
or at the onset of the attack. The results of this study suggests that the provocative
action of nitroglycerine in cluster headache is due, at least in part, to activation
of the trigeminovascular system. This mechanism seems to be slow and unrelated
to the well-known rapidly occurring vasodilator effects of the drug. Finally,
activation of the trigeminovascular system only occurs in those patients already
in an active cluster headache period who also have high basal CGRP-LI plasma levels.
This suggests that a hyperactivity of trigeminal nociceptive fibres could make
the trigeminovascular system of these patients sensitive to the triggering action
of nitroglycerine." [Abstract/Full
Ashina M, Bendtsen L, Jensen R, Schifter
S, Olesen J.
Calcitonin gene-related peptide levels during nitric
oxide-induced headache in patients with chronic tension-type headache.
J Neurol. 2001 Mar;8(2):173-8.
"It has been proposed that nitric oxide
(NO) induced headache in primary headaches may be associated with release of calcitonin
gene-related peptide (CGRP). In the present study we aimed to investigate plasma
levels of CGRP during headache induced by the NO donor glyceryl trinitrate (GTN)
in 16 patients with chronic tension-type headache and 16 healthy controls. The
subjects were randomly allocated to receive 0.5 microg/kg/min GTN or placebo over
20 min on two headache-free days. Blood samples were collected at baseline, 10,
20 and 60 min after start of infusion. Both patients and controls developed significantly
stronger immediate headache on the GTN day than on the placebo day and the headache
was significantly more pronounced in patients than in controls. There was no difference
between the area under the CGRP curve (AUCCGRP) on GTN vs. placebo day in either
patients (P=0.65) or controls (P=0.48). The AUCCGRP recorded on the GTN day did
not differ between patients and controls (P=0.36). Both in patients and controls,
CGRP levels changed significantly over time, on both the GTN and placebo days
(P < 0.05). The present study indicates that NO-induced immediate headache
is not associated with release of CGRP." [Abstract]
T, Dux M, Messlinger K.
Nitric oxide releases calcitonin-gene-related
peptide from rat dura mater encephali promoting increases in meningeal blood flow.
Vasc Res. 2002 Nov-Dec;39(6):489-96.
"Nitric oxide (NO) and calcitonin-gene-related
peptide (CGRP) are implicated in the pathophysiology of vascular headaches. We
studied the interaction of these two vasodilatory mediators in an animal model
and suggest that NO may increase meningeal blood flow not only by its direct vasodilatory
action but also by stimulating CGRP release. First, CGRP release from the rat
cranial dura mater was measured in vitro using an enzyme immunoassay. Hemisected
skulls with adhering dura mater were filled with synthetic interstitial fluid
and stimulated with the NO donor diethylamine-NONOate (10(-5)-10(-3) M) or with
NO gas (1,000 ppm), which caused concentration-dependent increases in CGRP release
up to 166.8%. Second, meningeal blood flow was recorded in vivo in the exposed
dura mater using laser Doppler flowmetry. Topical application of the NO donors
NONOate, S-nitroso-N-acetylpenicillamine and N-ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino)-ethenamine
(10(-5)-10(-3) M) caused concentration-dependent increases in blood flow. These
increases were significantly reduced by local preliminary application of the CGRP
receptor antagonist CGRP(8-37) (10(-4) M). We conclude that NO stimulates the
release of CGRP from dural afferents. The blood-flow-increasing effect of NO seems
to be partly mediated by CGRP. The interaction of NO and CGRP may be relevant
for the development of vascular headaches." [Abstract]
T, Messlinger K.
[Neuropeptide release in the dura mater encephali
in response to nitric oxide--relevance for the development of vascular headaches?]
"Nitric oxide (NO) and calcitonin gene-related
peptide (CGRP), potent vasodilators in the meninges,may be involved in the pathophysiology
of vascular headaches such as migraine pain. NO donators can provoke headache
attacks in migraineurs and increased levels of CGRP have been found in the venous
outflow from the head during migraine attacks. We therefore examined the effect
of both NO and CGRP on dural blood, a process which may parallel nociceptive processes
in the meninges. 1.Arterial blood flow was measured in the exposed dura mater
encephali of the rat using laser Doppler flowmetry. Local application of different
NO donors (SNAP,NONOate, and NOC-12) caused dose-dependent increases in meningeal
blood flow. CGRP(8-37) at 10(-4) M did not significantly change the basal flow
but attenuated increases in blood flow caused by the NO donors at concentrations
of 10(-5)-10(-3) M.2. In another series of experiments, the hemisected skulls
of adult Wistar rats, complete with intact dura mater, were filled with oxygenated
synthetic interstitial fluid (SIF) and the CGRP content of this fluid was assessed
every 5 min. When the NO donator NONOate, at concentrations of 10(-5)-10(-3) M,
was added to the SIF, or when the SIF was bubbled with NO gas (1000 ppm in N(2)
atmosphere) instead of carbogen, CGRP release increased in a concentration-dependent
manner. We conclude that the vasodilatory effect of NO that causes increased meningeal
blood flow is in part the result of both stimulating the release of CGRP and promoting
the vasodilatory action of CGRP. Since NO donors such as nitroglycerin are known
to provoke headache and CGRP is released during migraine pain, the NO-stimulated
CGRP release may be relevant for the development of vascular headaches that are
accompanied by meningeal hyperaemia." [Abstract]
S, Williamson DJ, Kaube H, Goadsby PJ.
Nitric oxide synthase inhibitors
can antagonize neurogenic and calcitonin gene-related peptide induced dilation
of dural meningeal vessels.
Br J Pharmacol. 2002 Sep;137(1):62-8.
The detailed pathophysiology of migraine is beginning to be understood and is
likely to involve activation of trigeminovascular afferents. 2. Clinically effective
anti-migraine compounds are believed to have actions that include peripheral inhibition
of calcitonin gene-related peptide (CGRP) release from trigeminal neurones, or
preventing dural vessel dilation, or both. CGRP antagonists can block both neurogenic
and CGRP-induced dural vessel dilation. 3. Nitric oxide (NO) can induce headache
in migraine patients and often triggers a delayed migraine. The initial headache
is thought to be caused via a direct action of the NO-cGMP pathway that causes
vasodilation by vascular smooth muscle relaxation, while the delayed headache
is likely to be a result of triggering trigeminovascular activation. Nitric oxide
synthase (NOS) inhibitors are effective in the treatment of acute migraine. 4.
The present studies used intravital microscopy to examine the effects of specific
NOS inhibitors on neurogenic dural vasodilation (NDV) and CGRP-induced dilation.
5. The non-specific and neuronal NOS (nNOS) inhibitors were able to partially
inhibit NDV, while the non-specific and endothelial NOS (eNOS) inhibitors were
able to partially inhibit the CGRP induced dilation. 6. There was no effect of
the inducible NOS (iNOS) inhibitor. 7. The data suggest that the delayed headache
response triggered by NO donors in humans may be due, in part, to increased nNOS
activity in the trigeminal system that causes CGRP release and dural vessel dilation.
8. Further, eNOS activity in the endothelium causes NO production and smooth muscle
relaxation by direct activation of the NO-cGMP pathway, and may be involved in
the initial headache response." [Abstract]
A, Multon S, Malgrange B, Parducz A, Vecsei L, Schoenen J.
of systemic nitroglycerin on CGRP and 5-HT afferents to rat caudal spinal trigeminal
nucleus and its modulation by estrogen.
Eur J Neurosci.
"Systemic administration of nitroglycerin, a nitric
oxide donor, triggers in migraine patients a delayed attack of unknown mechanism.
After puberty migraine is more prevalent in women. Attacks can be triggered by
abrupt falls in plasma estrogen levels, which accounts in part for sexual dimorphism,
but lacks an established neurobiological explanation. We studied the effect of
nitroglycerin on the innervated area of calcitonin gene-related peptide (CGRP)
and serotonin-immunoreactive afferents to the superficial laminae of the spinal
portion of trigeminal nucleus caudalis, and its modulation by estrogen. In male
rats, nitroglycerin produced after 4 h a significant decrease of the area innervated
by CGRP-immunoreactive afferents and an increase of that covered by serotonin-immunoreactive
fibres. These effects were not observed in the superficial laminae of thoracic
dorsal horns. The effect of nitroglycerin was similar in ovariectomized females.
In estradiol-treated ovariectomized females the area in the spinal portion of
trigeminal nucleus caudalis laminae I-II covered by CGRP-immunoreactive fibres
was lower and that of serotonin-immunoreactive fibres was higher than in males
and for both transmitters not significantly changed after nitroglycerin. The bouton
size of CGRP profiles was smaller in estradiol-treated ovariectomized females,
whereas after nitroglycerin it decreased significantly but only in males and ovariectomized
females. Nitroglycerin, i.e. nitric oxide, is thus able to differentially influence
afferent fibres in the superficial laminae of rat spinal trigeminal nucleus caudalis.
Estradiol modulates the basal expression of these transmitters and blocks the
nitroglycerin effect. These data may contribute to understanding the mechanisms
by which estrogens influence migraine severity and the triggering of attacks by
nitric oxide." [Abstract]
T, Dux M, Messlinger K.
Increase in meningeal blood flow by nitric
oxide--interaction with calcitonin gene-related peptide receptor and prostaglandin
Cephalalgia. 2002 Apr;22(3):233-41.
study addresses possible interactions of the vasodilators nitric oxide (NO), calcitonin
gene-related peptide (CGRP) and prostaglandins, which may be implicated in the
generation of vascular headaches. Local application of the NO donator diethylamine-NONOate
(NONOate) to the exposed dura mater encephali of the rat caused dose-dependent
increases in meningeal blood flow recorded by laser Doppler flowmetry. Pre-application
of the CGRP receptor antagonist CGRP8-37 significantly attenuated the evoked blood
flow increases, while the cyclooxygenase inhibitors acetylsalicylic acid and metamizol
were only marginally effective. Stimulation of rat dura mater with NONOate in
vitro caused increases in CGRP release. NADPH-diaphorase activity indicating NO
production was restricted to the endothelium of dural arterial vessels. We conclude
that increases in meningeal blood flow caused by NO depend partly on the release
and vasodilatory action of CGRP from dural afferents, while prostaglandins are
not significantly involved." [Abstract]
Eltorp CT, Jansen-Olesen I, Hansen AJ.
of calcitonin gene-related peptide (CGRP) from guinea pig dura mater in vitro
is inhibited by sumatriptan but unaffected by nitric oxide.
"Migraine attacks can be provoked by administration
of nitroglycerin, suggesting a role for nitric oxide (NO). The fact that release
of the neuropeptide CGRP from trigeminal sensory nerves occurs during the pain
phase of migraine and that NO can augment transmitter release prompted us to study
CGRP release from the in situ dura mater in guinea pig skulls. Release of CGRP
by capsaicin or by high potassium concentration was concentration-dependent and
counteracted in calcium-free medium. The anti-migraine compound, sumatriptan,
inhibited CGRP release via the 5-HT1-receptor. The NO donors, nitroglycerin, sodium
nitroprusside and S-nitroso-N-acetylpenicillamine did not influence CGRP release,
alone or together with the stimulants. We concluded that the skull preparation
is well suited for scrutinizing CGRP release from dura mater. The fact that sumatriptan
inhibits CGRP release as in migraine patients suggests a use for the present preparation
in headache research." [Abstract]
S, Williamson DJ, Kaube H, Goadsby PJ.
The effect of anti-migraine
compounds on nitric oxide-induced dilation of dural meningeal vessels.
J Pharmacol. 2002 Oct 4;452(2):223-8.
"Migraine is characteristically
accompanied by a throbbing quality of head pain thought to involve trigeminovascular
afferents. Administration of nitric oxide (NO) donors provides the most reliable
model of migraine induction in humans. The present studies used intravital microscopy
to monitor the effect of local meningeal nerve stimulation and NO on dural blood
vessels and any modulation of that effect by anti-migraine compounds. NO caused
an immediate and reproducible dilation of meningeal blood vessels that was partially
blocked by sumatriptan and indomethacin, while flunarizine and histamine H(1)
and H(2) receptor antagonists were unable to block the dilation. Indomethacin
also inhibited the neurogenic dilation while flunarizine did not. The present
studies demonstrate that NO is unlikely to interact with histamine to produce
its dilatory response. Sumatriptan and indomethacin inhibit the NO response by
inhibiting trigeminal activation and calcitonin gene-related peptide (CGRP) release.
Flunarizine does not modify either the neurogenic vasodilator response or the
NO meningeal dilator response at least acutely." [Abstract]
LH, Haderslev PA, Jacobsen VB, Iversen HK, Sperling B, Olesen J.
may play a causative role in migraine.
"Calcitonin gene-related peptide (CGRP) has been detected
in increased amounts in external jugular venous blood during migraine attacks.
However, it is unknown whether this is secondary to migraine or whether CGRP may
cause headache. In a double-blind crossover study, the effect of human alphaCGRP
(2 microg/min) or placebo infused intravenously for 20 min was studied in 12 patients
suffering from migraine without aura. Headache intensity was scored on a scale
from 0 to 10. Two patients were excluded due to severe hypotension and one because
she had an infection. In the first hour median peak headache score was 1.0 in
the halphaCGRP group vs. 0 in the placebo group (P < 0.01). During the following
11 h all patients experienced headaches after halphaCGRP vs. one patient after
placebo (P = 0.0004). The median maximal headache score was 4 after CGRP and 0
after placebo (P = 0.006). In three patients after halphaCGRP, but in no patients
after placebo, the delayed headache fulfilled the IHS criteria for migraine without
aura. As intravenous administration of halphaCGRP causes headache and migraine
in migraineurs, our study suggests that the increase in CGRP observed during spontaneous
migraine attacks may play a causative role." [Abstract]
Goadsby PJ, Edvinsson L, Ekman R.
peptide release in the extracerebral circulation of humans during migraine headache.
Neurol. 1990 Aug;28(2):183-7.
"The innervation of the cranial vessels
by the trigeminal nerve, the trigeminovascular system, has recently been the subject
of study in view of its possible role in the mediation of some aspects of migraine.
Since stimulation of the trigeminal ganglion in humans leads to facial pain and
flushing and associated release of powerful neuropeptide vasodilator substances,
their local release into the extracerebral circulation of humans was determined
in patients who had either common or classic migraine. Venous blood was sampled
from both the external jugular and cubital fossa ipsilateral to the side of headache.
Plasma levels of neuropeptide Y, vasoactive intestinal polypeptide, substance
P, and calcitonin gene-related peptide were determined using sensitive radioimmunoassays
for each peptide, and values for the cubital fossa and external jugular and a
control population were compared. A substantial elevation of the calcitonin gene-related
peptide level in the external jugular but not the cubital fossa blood was seen
in both classic and common migraine. The increase seen in classic migraine was
greater than that seen with common migraine. The other peptides measured were
unaltered. This finding may have importance in the pathophysiology of migraine."
V, Sarchielli P, Floridi A, Franceschini M, Codini M, Glioti G, Trequattrini A,
Vasoactive peptide levels in the plasma of young migraine
patients with and without aura assessed both interictally and ictally.
"We measured, by RIA methods, ictal and interictal
levels of substance P (SP), calcitonin-gene related peptide (CGRP) and neurokinin
A (NKA) in the plasma of 30 young migraine patients with aura (MPA) and 45 migraine
patients without aura (MWA), and compared the results with those of 30 age-matched
controls. There were no significant differences between the levels of these vasoactive
peptides in the control group and the levels in both migraine groups studied in
headache-free periods. An elevation of CGRP levels in plasma was found during
attacks in MPA and, to a lesser extent, in MWA (p < 0.03 and p < 0.05, respectively).
A significant increase in NKA levels was also demonstrated in the MPA and MWA
groups (p < 0.02 and p < 0.04, respectively). These data suggest, although
indirectly, that CGRP and NKA could be involved in the pathogenesis of migraine
attacks in juvenile migraine patients." [Abstract]
V, Alberti A, Gallai B, Coppola F, Floridi A, Sarchielli P.
and nitric oxide pathway in chronic daily headache: evidence from cerebrospinal
Cephalalgia. 2003 Apr;23(3):166-74.
substance P (SP) and calcitonin gene-related peptide (CGRP), and to a lesser extent
neurokinin A, were significantly increased in CSF compared with control subjects,
their values did not correlate with glutamate, nitrites and cGMP levels in CSF
in the patient group." [Abstract]
P, Alberti A, Floridi A, Gallai V.
Levels of nerve growth factor
in cerebrospinal fluid of chronic daily headache patients.
2001 Jul 10;57(1):132-4.
"Nerve growth factor (NGF) levels were determined
in the CSF of patients with chronic daily headache (CDH) and correlated with levels
of sensory neuropeptides. Patients with CDH showed higher NGF levels in the CSF
compared with control subjects (p < 0.0001). Higher CSF levels of substance
P (SP) (p < 0.002) and calcitonin-gene-related peptide (CGRP) (p < 0.0001)
were also found. There was a significant positive correlation between NGF and
both SP and CGRP values. These findings suggest that NGF is involved in the long-lasting
sensitization and sustained activation of the trigeminal system in CDH."
HP, Eich W, Russell IJ.
A possible role for saliva as a diagnostic
fluid in patients with chronic pain.
Semin Arthritis Rheum.
"OBJECTIVES: The focus of this review was on proteins
and peptides found in saliva. Of greatest interest were those neuropeptides relevant
to nociception and to the pathogenesis of chronic pain syndromes. An additional
goal was to develop a standardized protocol to collect saliva for laboratory assessment.
METHODS: Data were obtained through discussion with experts at the medical schools
in San Antonio and Heidelberg and a Medline literature search involving all relevant
studies from 1966 to 1997. The literature search was based on the following key
terms: saliva, serotonin, neuropeptide, substance P (SP), calcitonin gene-related
peptide (CGRP), and nerve growth factor (NGF). RESULTS: The mean concentration
of SP in the saliva of healthy normal controls ranged from 9.6 to 220 pg/mL. Generally,
the concentration of SP was approximately three times higher in saliva than in
plasma. In a number of painful conditions, particularly tension headache, substantial
elevations of salivary SP were found. Mean values for salivary CGRP in healthy
controls were approximately 22 pmol/L and were significantly elevated in patients
with migraine attacks or cluster headache. There were no data to indicate prior
quantitative determination of NGF in human saliva. CONCLUSIONS: After sampling
and processing techniques have been standardized, measurement of neuropeptides
in human saliva could provide a valuable tool for study of patients with chronic
painful disorders such as rheumatoid arthritis, osteoarthritis, and even fibromyalgia
PJ, Edvinsson L.
Human in vivo evidence for trigeminovascular activation
in cluster headache. Neuropeptide changes and effects of acute attacks therapies.
1994 Jun;117 ( Pt 3):427-34.
"Cluster headache is a rare very severe disorder
that is clinically well characterized with a relatively poorly understood pathophysiology.
In this study patients with episodic cluster headache fulfilling the criteria
of the International Headache Society were examined during an acute spontaneous
attack of headache to determine the local cranial release of neuropeptides. Blood
was sampled from the external jugular vein ipsilateral to the pain before and
after treatment of the attack. Samples were assayed for calcitonin gene-related
peptide (CGRP), vasoactive intestinal polypeptide (VIP), substance P and neuropeptide
Y. Attacks were treated with either oxygen inhalation, sumatriptan or an opiate.
Thirteen patients were studied of whom 10 were male and three female. All had
well-established typical attacks of cluster headache when blood was sampled. During
the attacks external jugular vein blood levels of CGRP and VIP were raised while
there was no change in neuropeptide Y or substance P. Calcitonin gene-related
peptide levels rose to 110 +/- 7 pmol/l (normal: < 40) while VIP levels rose
to 20 +/- 3 pmol/l (normal: < 7). Treatment with both oxygen and subcutaneous
sumatriptan reduced the CGRP level to normal, while opiate administration did
not alter the peptide levels. These data demonstrate for the first time in vivo
human evidence for activation of the trigeminovascular system and the cranial
parasympathetic nervous system in an acute attack of cluster headache. Furthermore,
it is shown that both oxygen and sumatriptan abort the attacks and terminate activity
in the trigeminovascular system." [Abstract]
M, Bendtsen L, Jensen R, Schifter S, Jansen-Olesen I, Olesen J.
levels of calcitonin gene-related peptide in chronic tension-type headache.
2000 Nov 14;55(9):1335-40.
"BACKGROUND: Calcitonin gene-related peptide
(CGRP) is involved in the pathophysiology of migraine and cluster headache. Whether
CGRP has any role in chronic tension-type headache is unknown. OBJECTIVES: To
compare interictal plasma levels of CGRP between patients with chronic tension-type
headache and healthy control subjects, to investigate plasma CGRP in relation
to headache state, and to compare plasma CGRP between the peripheral and the cranial
circulation. METHODS: Blood from the antecubital vein was drawn from 30 patients
with chronic tension-type headache and 34 healthy control subjects. In addition,
blood samples from the consecutive first 15 patients and from the consecutive
first 20 healthy control subjects were also collected from the external jugular
vein. RESULTS: CGRP levels measured in the peripheral circulation in patients
on days without headache, 63+/-5 pmol/L, tended to be higher than CGRP levels
in control subjects, 53+/-3 pmol/L (p = 0.06). In patients, no differences were
found between CGRP levels assessed ictally and interictally in either the cranial
(p = 0.91) or the peripheral (p = 0.62) circulation. Plasma CGRP level was higher
in the external jugular vein than in the antecubital vein on days without headache
(p = 0.03) but not on days with headache (p = 0.82). In control subjects, CGRP
levels in the cranial circulation did not differ from CGRP levels in the peripheral
circulation (p = 0.92). Exploratory analyses showed that 8 patients whose usual
headache quality was throbbing had a higher interictal plasma CGRP level than
control subjects (p = 0.002), whereas plasma CGRP level was normal in 22 patients
with pressing headaches (p = 0.36). CONCLUSIONS: Plasma levels of CGRP are normal
in patients with chronic tension-type headache and are unrelated to headache state.
Interictal plasma CGRP was increased in patients with a pulsating pain quality.
Because the authors have previously shown a similar increase of interictal CGRP
levels in migraine, this study suggests that headaches with symptoms that fulfill
International Headache Society criteria for tension-type headache may be pathophysiologically
related to migraine, if the headache has a pulsating quality." [Abstract]
Calcitonin gene-related Peptide in tension-type headache.
2002 Jun 7;2(6):1527-31.
"In the last 10 years there has been increasing
interest in the role of calcitonin gene-related peptide (CGRP) in primary headaches.
Tension-type headache is one of the most common and important types of primary
headaches, and ongoing nociception from myofascial tissues may play an important
role in the pathophysiology of this disorder. CGRP sensory fibers are preferentially
located in the walls of arteries, and nerve fibers containing CGRP accompany small
blood vessels in human cranial muscles. It is well established that nociception
may lead to release of CGRP from sensory nerve endings and from central terminals
of sensory afferents into the spinal cord. It has also been shown that density
of CGRP fibers around arteries is increased in persistently inflamed muscle. These
findings indicate that ongoing activity in sensory neurons in the cranial muscles
may be reflected in changes of plasma levels of neuropeptides in patients with
chronic tension-type headache. To explore the possible role of CGRP in tension-type
headache, plasma levels of CGRP were measured in patients with chronic tension-type
headache. This study showed that plasma levels of CGRP are normal in patients
and unrelated to headache state. However, the findings of normal plasma levels
of CGRP do not exclude the possibility that abnormalities of this neuropeptide
at the neuronal or peripheral (pericranial muscles) levels play a role in the
pathophysiology of tension-type headache. Investigation of CGRP in other compartments
with new sensitive methods of analysis is necessary to clarify its role in tension-type
M, Bendtsen L, Jensen R, Schifter S, Olesen J.
Evidence for increased
plasma levels of calcitonin gene-related peptide in migraine outside of attacks.
"Although calcitonin gene-related peptide (CGRP)
has been shown to be elevated in jugular venous blood of adult migraineurs during
acute migraine attacks, it remains unknown whether CGRP is increased outside of
attacks in jugular or cubital venous blood. The aim of the present study was to
compare interictal plasma levels of CGRP in adult migraine patients and in healthy
controls. Twenty patients with a diagnosis of migraine with or without aura and
20 healthy controls were included. In blood from the cubital vein, CGRP levels
were significantly higher in patients (75+/-8 pmol/l (mean+/-SEM)) than in controls
(49+/-3 pmol/l) (P=0.005). The subgroup of patients suffering exclusively from
migraine without aura (n=14) also had significantly higher levels of CGRP (82+/-10
pmol/l) than controls (n=20; 49+/-3 pmol/l) (P=0.001). The findings could not
be explained by confounding factors such as age, sex or use of contraceptive pills.
We therefore conclude that CGRP is increased in cubital venous blood of migraineurs
outside of attack. It is hypothesized that this finding may reflect a long-lasting
or permanent abnormal neurogenic vascular control in patients with migraine."
Sensory nerves in man and their role in primary headaches.
"The sensory innervation of intracranial vessels
originate in the trigeminal ganglion and comprise the following signal substances;
calcitonin gene-related peptide (CGRP), substance P, neurokinin A, pituitary adenylate
cyclase activating peptide (PACAP) and nitric oxide (NO). Studies in patients
have revealed a clear association between head pain and the release of CGRP. In
cluster headache and in a case of chronic paroxysmal headache there is in addition
release of vasoactive intestinal peptide (VIP), which was associated with the
facial symptoms (nasal congestion, rhinorrhea). In parallel with triptan administration,
acting via 5-HT(1B/1D) receptors, head pain subside and neuropeptide release normalise.
These data show the involvement of sensory and parasympathetic mechanisms in the
pathophysiology of primary headaches." [Abstract]
L, Olesen J, Olsen TS, Karle A, Ekman R, Fahrenkrug J.
vasoactive peptide release from brain to cerebral circulation during onset of
migraine with aura.
Cephalalgia. 1994 Feb;14(1):47-54.
eight patients carotid angiography was required for evaluation of transient neurological
attacks. Cerebral blood flow results, angiography and clinical observations subsequently
suggested the diagnosis of migraine. We measured plasma concentrations of substance
P(SP), neuropeptide Y (NPY), calcitonin gene-related peptide (CGRP) and vasoactive
intestinal peptide (VIP) in repeated blood samples obtained from the carotid artery
and the internal jugular vein in conjunction with cerebral angiography followed
by 4 to 6 repeated recordings of regional cerebral blood flow (rCBF) with the
intracarotid Xenon-133 injection technique. This technique is known to induce
attacks of migraine with aura in many sufferers. Four patients developed aura
symptoms. In three this was succeeded by throbbing headache. Typical, migraine-related,
focal hypoperfusion occurred in conjunction with the aura symptoms. The remaining
four patients had no symptoms or rCBF changes. There were no systematic or statistically
significant changes over time in arterial-venous plasma concentrations or in the
release rates of any of the peptides. All migraineurs had an overall elevated
mean CGRP value compared to control values from the literature. The overall plasma
levels of the potent vasoconstrictor NPY were higher (p < 0.10) in the group
that developed symptoms and rCBF changes (136 pmol/l) than in the non-symptomatic
group (97 pmol/l). The difference in NPY levels could perhaps be associated with
the focal rCBF decrease seen in the attack group." [Abstract]
K, Kanemasa T, Minagawa K, Kagawa K, Yagami T, Nakajima M, Ninomiya M.
a P/Q-type Ca(2+) channel blocker, inhibits neurogenic vasodilation and extravasation
following electrical stimulation of trigeminal ganglion.
Res. 2000 Aug 4;873(1):94-101.
"In this study, we investigated the effect
of alpha-eudesmol, which potently inhibits the presynaptic omega-agatoxin IVA-sensitive
(P/Q-type) Ca(2+) channel, on neurogenic inflammation following electrical stimulation
of rat trigeminal ganglion. Treatment with alpha-eudesmol (0.1-1 mg/kg. i.v.)
dose-dependently attenuated neurogenic vasodilation in facial skin monitored by
a laser Doppler flowmetry. In addition, alpha-eudesmol (1 mg/kg. i.v.) significantly
decreased dural plasma extravasation in analysis using Evans blue as a plasma
marker. On the other hand, alpha-eudesmol (1 mg/kg, i.v.) did not affect mean
arterial blood pressure in rats. The calcitonin gene-related peptide (CGRP) and
substance P (SP) released from activated sensory nerves have recently been suggested
to be associated with the neurogenic inflammation. In this study, we also showed
that alpha-eudesmol (0.45-45 microM) concentration-dependently inhibits the depolarization-evoked
CGRP and SP release from sensory nerve terminals in spinal cord slices. These
results indicate that the anti-neurogenic inflammation action of alpha-eudesmol,
which does not affect the cardiovascular system, may be due to its presynaptic
inhibition of the neuropeptide release from perivascular trigeminal terminals.
We also suggest that the omega-agatoxin IVA-sensitive Ca(2+) channel blocker,
alpha-eudesmol, may become useful for the treatment of the neurogenic inflammation
in the trigemino-vascular system such as migraine." [Abstract]
RD, Edvinsson L, Ekman R, Lambert GA.
Cortical spreading depression
does not result in the release of calcitonin gene-related peptide into the external
jugular vein of the cat: relevance to human migraine.
1993 Jun;13(3):180-3; discussion 149.
"There is circumstantial evidence
that cortical spreading depression (SD) may account for the scotoma and the "spreading
cortical oligemia" seen during migraine with aura. It has been shown that
calcitonin gene-related peptide (CGRP) is increased in blood taken from the external
jugular vein (EJV) in humans during migraine and after stimulation of the trigeminal
ganglion. To test the hypothesis that cortical SD may elevate the concentration
of this vasoactive peptide in the EJV during migraine, we have measured its concentration
in the external jugular vein of cats during cortical SD. This study demonstrates
that SD has no effect on the concentration of CGRP either during the passage of
a wave of spreading depression across the cortex or, 60 min later, during the
period of post-SD cortical oligemia." [Abstract]
DJ, Shepheard SL, Cook DA, Hargreaves RJ, Hill RG, Cumberbatch MJ.
of opioid receptors in neurogenic dural vasodilation and sensitization of trigeminal
neurones in anaesthetized rats.
Br J Pharmacol. 2001 Jul;133(6):807-14.
headache is thought to be caused by a distension of meningeal blood vessels, the
activation of trigeminal sensory neurones and the the development of a central
sensitization within the trigeminal nucleus caudalis (TNC). It has been proposed
that clinically effective 5-HT(1B/1D) agonists act peripherally to inhibit the
release of calcitonin gene-related peptide (CGRP) and neurogenic dural vasodilation,
and to attenuate nociceptive neurotransmission within the TNC. Since opioids are
also effective anti-migraine agents the present studies investigated the role
of opioids within the trigemino-vascular system in anaesthetised rats. Electrical
stimulation of the dura mater evoked neurogenic dural vasodilation which was significantly
inhibited by morphine (1 mg kg(-1)) the selective mu-opioid agonist DAGO (10 microg
kg(-1)) and the mixed agonist/antagonist butorphanol (1 mg kg(-1)) but not by
the kappa- and delta-opioid agonists (+/-) U50488H (100 microg kg(-1)) and DPDPE
(1 mg kg(-1)). Morphine had no effect on CGRP-evoked dural vasodilation. In electrophysiological
studies morphine (1 - 10 mg kg(-1)) significantly attenuated brainstem neuronal
activity in response to electrical stimulation of the dura by 65% at 10 mg kg(-1).
Morphine (3 mg kg(-1)) also inhibited the TNC neuronal sensitization following
CGRP-evoked dilation. The present studies have demonstrated that opioids block
the nociceptive neurotransmission within the trigeminal nucleus caudalis and in
addition inhibit neurogenic dural vasodilation via an action on mu-opioid receptors
located on trigeminal sensory fibres innervating dural blood vessels. These peripheral
and central actions are similar to those of the 'triptan' 5-HT(1B/1D) agonists
and could account for the anti-migraine actions of opioids." [Abstract]
S., Kaube, H., Goadsby, P. J.
Anandamide Is Able to Inhibit Trigeminal
Neurons Using an in Vivo Model of Trigeminovascular-Mediated Nociception
Pharmacol Exp Ther 2004 309: 56-63
AEA) is believed to be the endogenous ligand of the cannabinoid CB(1) and CB(2)
receptors. CB(1) receptors have been found localized on fibers in the spinal trigeminal
tract and spinal trigeminal nucleus caudalis. Known behavioral effects of anandamide
are antinociception, catalepsy, hypothermia, and depression of motor activity,
similar to Delta(9)-tetrahydocannanbinol, the psychoactive constituent of cannabis.
It may be a possible therapeutic target for migraine. In this study, we looked
at the possible role of the CB(1) receptor in the trigeminovascular system, using
intravital microscopy to study the effects of anandamide against various vasodilator
agents. Anandamide was able to inhibit dural blood vessel dilation brought about
by electrical stimulation by 50%, calcitonin gene-related peptide (CGRP) by 30%,
capsaicin by 45%, and nitric oxide by 40%. CGRP(8-37) was also able to attenuate
nitric oxide (NO)-induced dilation by 50%. The anandamide inhibition was reversed
by the CB(1) receptor antagonist AM251. Anandamide also reduced the blood pressure
changes caused by CGRP injection, this effect was not reversed by AM251. It would
seem that anandamide acts both presynaptically, to prevent CGRP release from trigeminal
sensory fibers, and postsynaptically to inhibit the CGRP-induced NO release in
the smooth muscle of dural arteries. CB(1) receptors seem to be involved in the
NO/CGRP relationship that exists in causing headache and dural blood vessel dilation.
It also seems that some of the blood pressure changes caused by anandamide are
mediated by a noncannabinoid receptor, as AM251 was unable to reverse these effects.
It can be suggested that anandamide is tonically released to play some form of
modulatory role in the trigeminovascular system." [Abstract]
New therapeutic target
in primary headaches - blocking theCGRP receptor.
Opin Ther Targets. 2003 Jun;7(3):377-83.
"The primary headaches are among
the most prevalent neurological disorders, afflicting up to 16% of the adult population.
The associated pain originates from intracranial blood vessels that are innervated
by sensory nerves storing several neurotransmitters. In primary headaches, there
is a clear association between the headache and the release of calcitonin gene-related
peptide (CGRP), but not other neuronal messengers. The specific purpose of this
review is to describe CGRP in the human cranial circulation and to elucidate a
possible role for a specific antagonist in the treatment of primary headaches.
Acute treatment with administration of a 5-HT(1B/1D) agonist (triptan) results
in alleviation of the headache and normalisation of the CGRP level. The mechanism
of action of triptans involves vasoconstriction of intracranial vessels and a
presynaptic inhibitory effect of sensory nerves. The central role of CGRP in migraine
and cluster headache pathophysiology has led to the search for small-molecule
CGRP antagonists, which are predicted to have fewer cardiovascular side effects
in comparison to the triptans. The initial pharmacological profile of such a group
of compounds has recently been disclosed. These compounds have high selectivity
for human CGRP receptors and are reportedly efficacious in the relief of acute
attacks of migraine." [Abstract]
J, Diener HC, Husstedt IW, Goadsby PJ, Hall D, Meier U, Pollentier S, Lesko LM;
BIBN 4096 BS Clinical Proof of Concept Study Group.
peptide receptor antagonist BIBN 4096 BS for the acute treatment of migraine.
Engl J Med. 2004 Mar 11;350(11):1104-10.
"BACKGROUND: Calcitonin gene-related
peptide (CGRP) may have a causative role in migraine. We therefore hypothesized
that a CGRP-receptor antagonist might be effective in the treatment of migraine
attacks. METHODS: In an international, multicenter, double-blind, randomized clinical
trial of BIBN 4096 BS, a highly specific and potent nonpeptide CGRP-receptor antagonist,
126 patients with migraine received one of the following: placebo or 0.25, 0.5,
1, 2.5, 5, or 10 mg of BIBN 4096 BS intravenously over a period of 10 minutes.
A group-sequential adaptive treatment-assignment design was used to minimize the
number of patients exposed. RESULTS: The 2.5-mg dose was selected, with a response
rate of 66 percent, as compared with 27 percent for placebo (P=0.001). The BIBN
4096 BS group as a whole had a response rate of 60 percent. Significant superiority
over placebo was also observed with respect to most secondary end points: the
pain-free rate at 2 hours; the rate of sustained response over a period of 24
hours; the rate of recurrence of headache; improvement in nausea, photophobia,
phonophobia, and functional capacity; and the time to meaningful relief. An effect
was apparent after 30 minutes and increased over the next few hours. The overall
rate of adverse events was 25 percent after the 2.5-mg dose of the drug and 20
percent for the BIBN 4096 BS group as a whole, as compared with 12 percent for
placebo. The most frequent side effect was paresthesia. There were no serious
adverse events. CONCLUSIONS: The CGRP antagonist BIBN 4096 BS was effective in
treating acute attacks of migraine." [Abstract]
P, Russo A.
New insights into the molecular actions of serotonergic
Pharmacol Ther. 2002 Apr-May;94(1-2):77-92.
is a painful and debilitating neurological disorder that affects approximately
10% of the adult population in Western countries. Sensitization and activation
of the trigeminal ganglia nerves that innervate the meningeal blood vessels is
believed to play an important role in the initiation and maintenance of migraine
pain. In this capacity, release of the neuropeptide calcitonin gene-related peptide
(CGRP) and the resultant neurogenic inflammation is thought to underlie the pathophysiology
of migraine. Largely due to the success of the serotonin Type 1 migraine drugs
such as sumatriptan, migraine pathology and therapy has become a focus of intensive
clinical and physiological research during the past decade. The effectiveness
of these drugs is thought to be due to their ability to block the stimulated secretion
of neuropeptides from trigeminal nerves to break the vicious nociceptive cycle
of migraine. A component of this nociceptive cycle involves activation of mitogen-activated
protein kinase signaling pathways. Indeed, activation of mitogen-activated protein
kinase pathways can increase CGRP neuropeptide synthesis and secretion. Recently,
the serotonin Type 1 agonists have been shown to cause a prolonged increase in
intracellular Ca(2+) in trigeminal ganglia neurons and an increased phosphatase
activity that can repress stimulated CGRP secretion and transcription. Identification
of molecular signaling events in migraine pathology and therapy has provided new
insight into the pharmacology and signaling mechanisms of sumatriptan and related
drugs, and may provide the foundation for development of novel treatments for
Development of CGRP antagonists for the treatment of migraine.
Opin Investig Drugs. 2001 Sep;2(9):1261-8.
"Migraine is one of the most
common neurological disorders, involving periodical attacks of headache and nausea
as well as a plethora of other symptoms. Although considerable progress has been
made, the pathophysiology of migraine is still not understood. However, several
observations point to an involvement of calcitonin gene-related peptide (CGRP).
Migraine headache involves the activation of the trigeminal system and dilatation
of cranial vessels. CGRP is localized to neurons in the trigeminal ganglia and
CGRP levels are increased during a migraine attack, presumably causing the vasodilation
observed. Accordingly, it is conceivable that inhibition of CGRP-evoked dilatation
of the cranial vessels may provide a novel treatment for migraine headache. The
non-peptidic CGRP antagonist BIBN-4096BS (Boehringer Ingelheim) is presently under
clinical investigation to assess the importance of CGRP in migraine headache and
to answer the question of whether the concept of CGRP antagonists may offer advantages,
e.g., higher efficacy, lower recurrence rate or improved side-effect profile,
compared to the currently used antimigraine drugs." [Abstract]
R, Bumann K, Kaumann AJ.
BIBN4096BS is a potent competitive antagonist
of the relaxant effects of alpha-CGRP on human temporal artery: comparison with
Br J Pharmacol. 2002 May;136(1):120-6.
of CGRP during migraine may produce harmful dilatation of cranial arteries, thereby
possibly causing pain. We have compared the antagonism by BIBN4096BS and CGRP(8-37)
of the relaxant effects of alpha-CGRP on rings of human temporal artery. alpha-CGRP
relaxed the arteries precontracted with 9 - 24 mM KCl (-logEC50=9.4) nearly as
efficaciously as sodium nitroprusside (10 microM). BIBN4096BS (0.1 - 100 nM) antagonized
the effects of alpha-CGRP in surmountable manner with slopes of Schild-plots not
different from unity. -LogKB values of 10.1 and 10.4 were estimated for BIBN4096BS
when administered before or during the KCl-contracture respectively. BIBN4096BS
(1 microM) did not modify the relaxant effects of papaverine and sodium nitroprusside.
CGRP(8-37) (1 - 10 microM) antagonized the effects of alpha-CGRP in a surmountable
manner with slopes of Schild-plots not different from unity. -LogKB values of
6.6 and 6.7 were estimated for CGRP(8-37) administered before or during the KCl-contracture
respectively. The high affinity of BIBN4096BS for CGRP receptors of human temporal
artery makes it an excellent tool to explore the hypothesis of CGRP-evoked cerebral
vasodilation in migraine." [Abstract]
MJ, Abounader R, Hebert E, Doods H, Hamel E.
Efficacy of the non-peptide
CGRP receptor antagonist BIBN4096BS in blocking CGRP-induced dilations in human
and bovine cerebral arteries: potential implications in acute migraine treatment.
"The present data demonstrate that BIBN4096BS is
a very potent antagonist that could, depending on its bioavailability and in vivo
affinity, be of potential benefit in the acute treatment of migraine headache
by blocking and/or reversing the CGRP-mediated dilation of intracranial vessels
induced by activation of trigeminovascular afferents." [Abstract]
Nambi, Daines, Robert A., Disa, Jyoti, Chambers, Pamela A., Sauermelch, Charles
F., Quiniou, Marie-J., Khandoudi, Nassirah, Gout, Bernard, Douglas, Stephen A.,
Willette, Robert N.
Pharmacology of SB-273779, a Nonpeptide Calcitonin
Gene-Related Peptide 1 Receptor Antagonist
J Pharmacol Exp
Ther 2001 296: 768-775 [Full
Durham, Paul L., Russo, Andrew F.
of the Calcitonin Gene-Related Peptide Enhancer by Mitogen-Activated Protein Kinases
and Repression by an Antimigraine Drug in Trigeminal Ganglia Neurons
Neurosci. 2003 23: 807-815
"Calcitonin gene-related peptide (CGRP) is
involved in the underlying pathophysiology of all vascular headaches, including
migraines. Elevated levels of CGRP during migraine are restored to normal coincident
with headache relief after treatment with the antimigraine drug sumatriptan. We
have used primary cultures of trigeminal neurons under conditions simulating migraine
pathology and therapy to study the mechanisms controlling the CGRP promoter. Using
reporter genes in transient transfection assays, we demonstrate that an 18 bp
enhancer containing a helix-loop-helix element is both necessary and sufficient
for full promoter activity. NGF treatment and cotransfection with an upstream
activator of the extracellular signal-regulated MAP kinases (MAPKs) activated
the enhancer. Treatment with sumatriptan repressed NGF- and MAPK-stimulated CGRP
promoter activity. Repression was also observed using a synthetic MAPK-responsive
reporter gene. Sumatriptan regulation of CGRP gene expression did not couple to
a G(i)/G(o) pathway, but rather caused a prolonged increase in intracellular calcium.
The importance of the prolonged calcium signal in repression of MAPK activity
was demonstrated by using the ionophore ionomycin to mimic sumatriptan action.
We propose that activation of MAPK pathways may increase CGRP gene expression
during migraine, and that sumatriptan can diametrically oppose that activation
via a prolonged elevation of intracellular calcium." [Full
Durham, Paul L., Russo, Andrew F.
of Calcitonin Gene-Related Peptide Secretion by a Serotonergic Antimigraine Drug
Neurosci. 1999 19: 3423-3429
"We have investigated the regulation of calcitonin
gene-related peptide (CGRP) release from trigeminal neurons by the serotonergic
antimigraine drug sumatriptan. Serum levels of the neuropeptide CGRP are elevated
during migraine. Treatment with the drug sumatriptan returns CGRP levels to normal
coincident with the alleviation of headache. However, despite this clinical efficacy,
the cellular target and mechanism of sumatriptan action are not well understood
beyond the pharmacology of its recognition of the 5-HT1 class of serotonin receptors.
We have used cultured trigeminal neurons to demonstrate that sumatriptan can directly
repress CGRP secretion from sensory neurons. The stimulated secretion in response
to depolarization or inflammatory agents was inhibited, but not the basal secretion
rate. Unexpectedly, sumatriptan did not lower cAMP levels, in contrast to the
classical role ascribed to the 5-HT1 receptors. Instead, activation of 5-HT1 receptors
caused a slow and remarkably prolonged increase in intracellular calcium. The
inhibition of CGRP secretion is attenuated by the phosphatase inhibitor okadaic
acid, suggesting that sumatriptan action is mediated by calcium-recruited phosphatases.
These results suggest that 5-HT1 agonists may block a deleterious feedback loop
in migraine at the trigeminal neurons and provide a general mechanism by which
this class of drugs can attenuate stimulated neuropeptide release." [Full
Knight YE, Edvinsson L, Goadsby PJ.
inhibits release of calcitonin gene-related peptide in the cat but only at doses
with 5HT(1B/1D) receptor agonist activity?
"Calcitonin gene-related peptide (CGRP) is a marker
for trigeminovascular activation and is released during the headache phase of
migraine and cluster headache. CGRP may have a role in migraine through its potent
cranial vasodilator effects, or by an action on trigeminal nerve activity, both
of which are targeted by 5HT(1B/1D) agonist drugs. CP122,288, a conformationally
restricted analogue of sumatriptan that is a potent inhibitor of neurogenic plasma
protein extravasation (PPE), was ineffective at inhibiting CGRP release at a single
low dose; and is also ineffective as an acute anti-migraine compound. However,
it remained unclear as to whether, as a class, the conformationally-restricted
triptan analogues could have inhibitory effects on CGRP in higher doses. 4991W93,
a conformationally restricted analogue of zolmitriptan, is also a potent inhibitor
of PPE at doses without 5HT(1B/1D)-mediated effects, that was developed as an
anti-migraine drug, and thus was suitable to test whether higher doses of such
conformationally restricted triptan analogues could inhibit trigeminal-evoked
CGRP release. The superior sagittal sinus (SSS) was stimulated in 14 anaesthetised
cats and external jugular vein blood samples were analysed by radioimmunoassay
for CGRP levels before, 1 min after SSS stimulation, and 1 min after SSS stimulation
in the presence of 4991W93. Stimulation of the SSS resulted in release of CGRP
from the external jugular vein. 4991W93 at a dose of 0.1 and 10 microg/kg, selected
for maximal PPE blocking effects in rodents, was ineffective at inhibiting CGRP
release, with an SSS stimulation level of 78+/-4 pmol/l compared to a post-4991W93
level of 79+/-3 pmol/l (n=4). In comparison CGRP release was inhibited after a
dose of 100 microg/kg 4991W93 from 64+/-6 to 36+/-3 pmol/l (n=5). Given that 4991W93
is inactive clinically at non-vascular doses, it seems clear that the 5HT(1B/1D)
agonist effects of the compound are necessary for blockade of CGRP release and
thus any anti-migraine action. Taken with the clinical results, these data emphasise
the importance of CGRP release in migraine, and suggest that other non-5HT-based
pharmacological targets may account for PPE blockade in animal studies."
DJ, Hargreaves RJ, Hill RG, Shepheard SL.
Sumatriptan inhibits neurogenic
vasodilation of dural blood vessels in the anaesthetized rat--intravital microscope
Cephalalgia. 1997 Jun;17(4):525-31.
study used intravital microscopy to measure the diameter of dural arteries in
anaesthetized rats. Electrical stimulation of the surface of a closed cranial
window produced increases in dural vessel diameter which were blocked by the CGRP
receptor antagonist human-alpha CGRP(8-37) but unaffected by the NK1 receptor
antagonist RP67580. Sumatriptan (3 and 10 mg kg-1, i.v.) significantly reduced
the response to electrical stimulation. In contrast, sumatriptan (3 mg kg-1) had
no effects on the response to exogenously administered CGRP. These results indicate
that neurokinins play no role in neurogenic vasodilation in this preparation and
that neurogenic vasodilation in rat dural vessels is mediated predominantly by
CGRP. Furthermore, the data indicate that sumatriptan attenuates neurogenic vasodilation,
probably by inhibiting the release of CGRP from perivascular trigeminal nerve
endings innervating the dura. These experimental data parallel the clinical findings
that CGRP levels are elevated in migraine and normalized, concomitantly with headache
relief, by sumatriptan." [Abstract]
DJ, Hill RG, Shepheard SL, Hargreaves RJ.
The anti-migraine 5-HT(1B/1D)
agonist rizatriptan inhibits neurogenic dural vasodilation in anaesthetized guinea-pigs.
J Pharmacol. 2001 Aug;133(7):1029-34.
"These studies investigated the
pharmacology of neurogenic dural vasodilation in anaesthetized guinea-pigs. Following
introduction of a closed cranial window the meningeal (dural) blood vessels were
visualized using intravital microscopy and the diameter constantly measured using
a video dimension analyser. Dural blood vessels were constricted with endothelin-1
(3 microg kg(-1), i.v.) prior to dilation of the dural blood vessels with calcitonin
gene-related peptide (CGRP; 1 microg kg(-1), i.v.) or local electrical stimulation
(up to 300 microA) of the dura mater. In guinea-pigs pre-treated with the CGRP
receptor antagonist CGRP((8-37)) (0.3 mg kg(-1), i.v.) the dilator response to
electrical stimulation was inhibited by 85% indicating an important role of CGRP
in neurogenic dural vasodilation in this species. Neurogenic dural vasodilation
was also blocked by the 5-HT(1B/1D) agonist rizatriptan (100 microg kg(-1)) with
estimated plasma levels commensurate with concentrations required for anti-migraine
efficacy in patients. Rizatriptan did not reverse the dural dilation evoked by
CGRP indicating an action on presynaptic receptors located on trigeminal sensory
fibres innervating dural blood vessels. In addition, neurogenic dural vasodilation
was also blocked by the selective 5-HT(1D) agonist PNU-142633 (100 microg kg(-1))
but not by the 5-HT(1F) agonist LY334370 (3 mg kg(-1)) suggesting that rizatriptan
blocks neurogenic vasodilation via an action on 5-HT(1D) receptors located on
perivascular trigeminal nerves to inhibit CGRP release. This mechanism may underlie
one of the anti-migraine actions of the triptan class exemplified by rizatriptan
and suggests that the guinea-pig is an appropriate species in which to investigate
the pharmacology of neurogenic dural vasodilation." [Abstract]
M, Covenas R, Csillik B, Ahangari R, Yajeya J, Riquelme R, Narvaez JA, Tramu G.
of substance P, neurokinin A and calcitonin gene-related peptide from the contralateral
and ipsilateral caudal trigeminal nucleus following unilateral electrical stimulation
of the trigeminal ganglion; a possible neurophysiological and neuroanatomical
link to generalized head pain.
J Chem Neuroanat. 2001 Mar;21(2):161-9.
trigeminal neurons of the trigeminal ganglion (TG) innervate major parts of the
face and head, including the dura. Electrical stimulation of the TG at specific
parameters, can activate its nociceptive neurons and may serve as an experimental
pain model. Markowitz [J. Neurosci. 7 (1987) 4129] reported that electrical stimulation
of the trigeminal ganglion (TG) causes extravasation of plasma proteins from venules
of the trigeminally innervated domain possibly due to the release of vasoactive
substances. Neurogenic inflammation (vasodilatation, plasma protein extravasation,
release of vasoactive peptides) in dura may serve as one of the possible pathomechanisms
underlying vascular head pain [Moskowitz, Ann. Neurol. 16 (1984) 157]. We performed
a unilateral electrical stimulation (7.5 Hz, 5 ms, 0.8-1.4 mA for 5 min) of the
TG in rat, to induce a neurogenic inflammation in the peripheral trigeminal domain
including the dura, looking for calcitonin gene related peptide (CGRP), substance
P (SP) and neurokinin A (NKA) immunoreactivity (IR) in the caudal trigeminal nucleus
(CTN) into which massive central trigeminal processes terminate. Here, we show
patchy depletion(s) of CGRP-, SP- and NKA-IRs in the contralateral CTN of the
rat in addition to their ipsilateral depletion. Such depletion is due to the release
of these neuropeptides in the CTN leading to the activation of bilateral trigeminal
nociceptive pathway. These data afford the possibility that under specific frequencies
(which may roughly correlate to the intensity of the painful stimulus) and/or
specific intensities (may correlate to specific areas of the peripheral trigeminal
domain) of stimulation, activation of one side of the TG may activate bilateral
trigeminal nociceptive pathway leading to the perception of an ill localized/generalized
pain or headache rather than a unilateral one." [Abstract]
Samsam M, Covenas R, Ahangari R, Yajeya J, Narvaez
JA, Tramu G.
Simultaneous depletion of neurokinin A, substance P
and calcitonin gene-related peptide from the caudal trigeminal nucleus of the
rat during electrical stimulation of the trigeminal ganglion.
2000 Feb;84(2-3):389-95. [Abstract]
DJ, Hargreaves RJ.
Neurogenic inflammation in the context of migraine.
Res Tech. 2001 May 1;53(3):167-78.
"Despite considerable research into
the pathogenesis of idiopathic headaches, such as migraine, the pathophysiological
mechanisms underlying them remain poorly understood. Although it is well established
that the trigeminal nerve becomes activated during migraine, the consequences
of this activation remain controversial. One theory, based on preclinical observations,
is that activation of trigeminal sensory fibers leads to a painful neurogenic
inflammation within the meningeal (dural) vasculature mediated by neuropeptide
release from trigeminal sensory fibres and characterized by plasma protein extravasation,
vasodilation, and mast cell degranulation. Effective antimigraine agents such
as ergots, triptans, opioids, and valproate inhibit preclinical neurogenic dural
extravasation, suggesting that this activity may be a predictor of potential clinical
efficacy of novel agents. However, several clinical trials with other agents that
inhibit this process preclinically have failed to show efficacy in the acute treatment
of migraine in man. Alternatively, it has been proposed that painful neurogenic
vasodilation of meningeal blood vessels could be a key component of the inflammatory
process during migraine headache. This view is supported by the observation that
jugular plasma levels of the potent vasodilator, calcitonin gene-related peptide
(CGRP) are elevated during the headache and normalized by successful sumatriptan
treatment. Preclinically, activation of trigeminal sensory fibers evokes a CGRP-mediated
neurogenic dural vasodilation, which is blocked by dihydroergotamine, triptans,
and opioids but unaffected by NK1 receptor antagonists that failed in clinical
trials. These observations suggest that CGRP release with associated neurogenic
dural vasodilation may be important in the generation of migraine pain, a theory
that would ultimately be tested by the clinical testing of a CGRP receptor antagonist."
A, Averbeck B, Messlinger K, Reeh PW.
Release of substance P, calcitonin
gene-related peptide and prostaglandin E2 from rat dura mater encephali following
electrical and chemical stimulation in vitro.
"Neurogenic inflammation of the dura, expressed
in plasma extravasation and vasodilatation, putatively contributes to different
types of headache. A novel in vitro preparation of the fluid-filled skull cavities
was developed to measure mediator release from dura mater encephali upon antidromic
electrical stimulation of the trigeminal ganglion and after application of a mixture
of inflammatory mediators (serotonin, histamine and bradykinin, 10(-5) M each,
pH 6.1) to the arachnoid side of rat dura. The release of calcitonin gene-related
peptide, substance P and prostaglandin E2 from dura mater was measured in 5-min
samples of superfusates using enzyme immunoassays. Orthodromic chemical and antidromic
electrical stimulation of dural afferents caused significant release of calcitonin
gene-related peptide (2.8- and 4.5-fold of baseline). The neuropeptide was found
to be increased during the 5-min stimulation period and returned to baseline (20.9
+/- 12 pg/ml) in the sampling period after stimulation. In contrast, release of
substance P remained at baseline levels (19.3 +/- 11 pg/ml) throughout the experiment.
Prostaglandin E2 release was elevated during chemical and significantly also after
antidromic electrical stimulation (6- and 4.2-fold of baseline, which was 305
+/- 250 pg/ml). Prostaglandin E2 release outlasted the stimulation period for
at least another 5 min. The data support the hypothesis of neurogenic inflammation
being involved in headaches and provide new evidence for prostaglandin E2 possibly
facilitating meningeal nociceptor excitation and, hence, pain." [Abstract]
DW, Feniuk W, Humphrey PP.
Characterization of the prostanoid receptor
types involved in mediating calcitonin gene-related peptide release from cultured
rat trigeminal neurones.
Br J Pharmacol. 2001 Nov;134(6):1296-302.
Prostaglandins and the vasodilator neuropeptide, calcitonin-gene related peptide
(CGRP), have both been implicated in the pathogenesis of migraine headache. We
have used primary cultures of adult rat trigeminal neurones to examine the effects
of prostanoids on CGRP release in vitro. 2. CGRP release was stimulated by prostaglandin
E2 (PGE2) and the IP receptor agonist, carbaprostacyclin (cPGI2). These responses
were extracellular calcium-dependent, and the PGE2-induced CGRP release was unaltered
by inhibition of nitric oxide synthase (NOS), ATP receptor blockade, or the addition
of adenosine deaminase. 3. Increases in CGRP levels were also observed in response
to prostaglandin D2 (PGD2), and the EP2 receptor selective agonist, butaprost.
No increases in CGRP release were observed in response to prostaglandin F2alpha
(PGF2alpha) or the TP receptor selective agonist, U46619, or the EP3 receptor
selective agonist, GR63799X. 4. The selective DP receptor antagonist, BWA868C,
antagonized the PGD2-, but not PGE2- or cPGI2-induced release. Furthermore, the
EP1 selective antagonist, ZM325802, failed to antagonize the PGE2-induced CGRP
release from these cells. 5. These data indicate that activation of DP, EP and
IP receptors can each cause CGRP release from trigeminal neurones, and suggest
that the predominant EP receptor subtype involved may be the EP2 receptor. Together
with evidence that the cyclo-oxygenase inhibitor, aspirin, particularly when administered
intravenously is effective in treating acute migraine, these findings further
suggest a role for prostaglandins in migraine pathophysiology." [Abstract]
K, Reeh PW, Averbeck B.
S+ -flurbiprofen but not 5-HT1 agonists suppress
basal and stimulated CGRP and PGE2 release from isolated rat dura mater.
"Neurogenic inflammation of the meninges, expressed
in plasma extravasation and vasodilatation, putatively contributes to certain
types of headache. Both, non-steroidal antiinflammatory drugs (NSAIDs) and serotonin-1
(5-HT1) receptor agonists are similarly effective antimigraine drugs but their
mechanism of action is unclear. The clinical observation that sumatriptan lowered
plasma levels of calcitonin gene-related peptide (CGRP), found increased during
migraine attacks, drew attention to a possible inhibition of pro-inflammatory
neuropeptide release from trigeminal afferents. An isolated preparation of fluid-filled
rat skull cavities was used to study effects of NSAIDs and 5-HT(1B/D) agonists
on the dura stimulated by inflammatory mediators (bradykinin, histamine and serotonin,
10(-5)M each). The release of immunoreactive CGRP (iCGRP) and immunoreactive PGE(2)
(iPGE(2)) was measured in 5-min samples of superfusates using enzyme immunoassays.
S(+)-flurbiprofen (10(-6)M) strongly reduced the basal and stimulated iCGRP release
and abolished iPGE(2) release; R(-)-flurbiprofen showed much less effect on iPGE(2)
liberation and did not influence iCGRP release. The 5-HT(1B/D) agonists naratriptan
and CP93,129 were ineffective on both iCGRP and iPGE(2) release. Inspite of its
weak COX blocking effect, R(-)-flurbiprofen is reported to exert antinociceptive
effects, although it has not been tested in migraine. Only the potent COX blocker
S(+)-flurbiprofen also suppressed iCGRP release while the 5-HT(1B/D) agonists
were ineffective. Thus, inhibition of meningeal neuropeptide secretion is not
a common action principle of the drugs that could be essential for their antimigraine
V, Katsarava Z, Liedert B, Guehring H, Schmitz K, Diener HC, Michel MC.
in vivo rat model to study calcitonin gene related peptide release following activation
of the trigeminal vascular system.
Pain. 2001 May;92(1-2):101-6.
gene related peptide (CGRP) released from the C-fibers projecting from the trigeminal
ganglion to the meninges has been suggested to play a crucial role in the pathophysiology
of headache, particularly migraine. In humans it has been shown that CGRP is released
during migraine-attacks, and this is attenuated by the administration of typical
anti-migraine drugs such as dihydroergotamine or sumatriptan. We describe a new
rat model which allows the study of CGRP release from the meninges into venous
blood following activation of the trigeminal vascular system. The effects of classical
and new anti-migraine drugs such as acetylsalicylic acid (ASA), sumatriptan and
the new high efficacy 5-HT1B/1D agonist donitriptan (4-[4-[2-(2-aminoethyl)-1H-indol-5-yloxyl]acetyl]piperazinyl-1-yl]benzonitrile)
were evaluated in comparison with the established model of neurogenic inflammation
in the meninges. Sumatriptan and donitriptan inhibited CGRP release as well as
neurogenic inflammation. ASA, however, attenuated neurogenic inflammation, but
not CGRP release, confirming the concept of prejunctional inhibition of CGRP release
by 5-HT1B/1D receptors. This new model allows the further study of prejunctional
pharmacology and mechanisms of neuropeptide release in the trigeminal vascular
system, which might be crucial for the further development of potent, more effective
anti-migraine drugs." [Abstract]
Durham PL, Dong PX, Belasco KT, Kasperski J, Gierasch WW,
Edvinsson L, Heistad DD, Faraci FM, Russo AF.
and regulation of CGRP promoter activity following viral gene transfer into cultured
trigeminal ganglia neurons.
Brain Res. 2004 Jan 30;997(1):103-10.
have examined the regulation of calcitonin gene-related peptide (CGRP) promoter
activity in primary cultures of rat trigeminal ganglia neurons. A viral vector
was used to circumvent the potential complication of examining only a small subpopulation
of cells in the heterogeneous cultures. Infection with high titers of recombinant
adenovirus containing 1.25 kb of the rat CGRP promoter linked to the beta-galactosidase
reporter gene (AdCGRP-lacZ) yielded expression in about 50% of the CGRP-expressing
neurons. The CGRP-lacZ reporter gene was preferentially expressed in neurons,
with 91% co-expression with endogenous CGRP. In contrast, an adenoviral vector
containing a CMV-lacZ reporter was predominantly expressed in non-neuronal cells,
with only 29% co-expression with CGRP. We then asked whether the CGRP promoter
in the viral vector could be regulated by serotonin receptor type 1 (5-HT(1))
agonists. Promoter activity was decreased two- to threefold by treatment with
five 5-HT(1B/D) agonists, including the triptan drugs sumatriptan, eletriptan,
and rizatriptan that are used for migraine treatment. As controls, CMV promoter
activity was not affected, and 5-HT(1B/D) receptor antagonists blocked the repression
caused by sumatriptan and eletriptan. Thus, adenoviral gene transfer can be used
in trigeminal ganglia neurons for studying the mechanisms of triptan drug action
on CGRP synthesis." [Abstract]
KR, Wainwright A, Edvinsson L, Pickard JD, Hill RG.
localization of calcitonin receptor-like receptor and receptor activity-modifying
proteins in the human cerebral vasculature.
J Cereb Blood
Flow Metab. 2002 May;22(5):620-9.
"Calcitonin gene-related peptide and
adrenomedullin belong to a structurally related neuropeptide family and are potent
vasodilators expressed in the trigeminovascular system. The molecular identity
of receptors for these proteins has only recently been elucidated. Central to
functional binding of these neuropeptides is the G-protein-coupled receptor, the
calcitonin receptor-like receptor (CRLR), whose cell surface expression and pharmacology
is determined by coexpression of a receptor activity-modifying protein (RAMP).
CRLR combined with RAMP binds calcitonin gene-related peptide with high affinity,
whereas CRLR coexpression with RAMP2 or -3 confers high-affinity binding of adrenomedullin.
The authors investigated the expression of these receptor components in human
cerebral vasculature to further characterize neuropeptide receptor content and
the potential functions of these receptors. Localization has been carried out
using specific antisera raised against immunogenic peptide sequences that were
subsequently applied using modern immunohistochemical techniques and confocal
microscopy. The results are the first to show the presence of these receptor component
proteins in human middle meningeal, middle cerebral, pial, and superficial temporal
vessels, and confirm that both calcitonin gene-related peptide and adrenomedullin
receptors may arise from the coassembly of RAMPs with CRLR in these vessel types.
These novel data advance the understanding of the molecular function of the trigeminovascular
system, its potential role in vascular headache disorders such as migraine, and
may lead to possible ways in which future synthetic ligands may be applied to
manage these disorders." [Abstract]
Smith D, Hill RG, Edvinsson L, Longmore J.
immunocytochemical investigation of human trigeminal nucleus caudalis: CGRP, substance
P and 5-HT1D-receptor immunoreactivities are expressed by trigeminal sensory fibres.
"5-HT1D (but not 5-HT1B)-receptor immunoreactivity
(i.r.) can be detected on trigeminal fibres within the spinal trigeminal tract
of the human brainstem. The present study used immunohistochemical and morphometric
techniques to determine the proportions of trigeminal fibres expressing substance
P, CGRP or 5-HT1D-receptor immunoreactivities. Co-localization studies between
5-HT1D-receptor and substance P- or CGRP-i.r. were also performed. Brainstem material
was obtained with consent (four donors) and the total number of immunoreactive
fibres within the trigeminal tract was estimated using random field sampling.
A greater proportion of fibres (>1 microm diameter) expressed CGRP-i.r. (80
+/- 6%) compared with substance P-i.r. (46 +/- 7%) or 5-HT1D-receptor-i.r. (25
+/- 1%). 5-HT1D-receptor-i.r. was co-localized on some CGRP- or substance P-i.r.
fibres. This suggests that 5-HT1D-receptors can regulate the release of CGRP and
substance P and may be relevant to the clinical effectiveness of 5-HT1B/1D-receptor
agonists in the treatment of migraine and other cranial pain syndromes."
Hou M, Kanje M, Longmore J, Tajti J, Uddman R, Edvinsson
5-HT(1B) and 5-HT(1D) receptors in the human trigeminal ganglion:
co-localization with calcitonin gene-related peptide, substance P and nitric oxide
Brain Res. 2001 Aug 3;909(1-2):112-20.
(5-HT) is implicated in migraine and agonist directed against 5-HT(1B) and 5-HT(1D)
receptors are commonly used as effective therapies. The antimigraine mechanisms
involve the inhibition of intracranial sensory neuropeptide release. In order
to determine which 5-HT(1) receptor subtypes are involved we have by immunocytochemistry
examined the distribution of 5-HT(1B) and 5-HT(1D) receptors in the human trigeminal
ganglia, and addressed which of them colocalize with calcitonin gene-related peptide
(CGRP), substance P (SP) or nitric oxide synthase (NOS). We detected that 5-HT(1D)
receptor immunoreactivity (i.r.) was predominantly expressed in medium-sized cells
(86% of positive cells, 30-60 microm). About 9% of the 5-HT(1D) receptor i.r.
cells were large in size (> 60 microm) and 5% were small in size (< 30 microm).
In a similar pattern, 5-HT(1B) receptor i.r. was mainly expressed in medium-sized
cells (81% in 30-60 microm, 15% in > 60 microm and 4% in < 30 microm). Double
immunostaining was used to determine whether the 5-HT(1B) or 5-HT(1D) receptor
immunoreactive cells co-localized with either CGRP, SP or NOS. Thus, 89% of the
CGRP i.r. cells expressed 5-HT(1D) receptor i.r. and 65% of the CGRP positive
cells were 5-HT(1B) receptor positive. Most of the 5-HT(1D) (95%) and the 5-HT(1B)
(94%) receptor i.r. cells showed SP immunostaining and 83% of 5-HT(1D) receptor
and 86% of 5-HT(1B) receptor i.r. cells contained NOS. In conclusion, both 5-HT(1B)
and 5-HT(1D) receptors are expressed in the human trigeminal ganglion and they
are mainly localized in medium-sized cells and they seem to colocalize with CGRP,
SP and NOS." [Abstract]
QP, Hill R, Sirinathsinghji D.
Colocalization of CGRP with 5-HT1B/1D
receptors and substance P in trigeminal ganglion neurons in rats.
J Neurosci. 2001 Jun;13(11):2099-104.
"Vasodilatation in the dura mater
has been implicated in migraine pathogenesis. Anti-migraine triptan drugs block
vasodilatation by binding to 5-HT1B/1D receptors localized on the peripheral sensory
terminals and dural blood vessel smooth muscles. Previous studies suggest that
calcitonin gene-related peptide (CGRP) released from Adelta-fibres plays a more
important role than substance P (SP) released from C-fibres in inducing dural
vasodilatation and that one of the antimigraine mechanisms of triptan drugs is
inhibiting CGRP release. In the present study, the relationship between CGRP and
5-HT1B/1D receptors, and between CGRP and SP in the trigeminal ganglion neurons
in rats was examined by double immunohistochemical staining. CGRP, 5-HT1B, 5-HT1D
and SP-positive trigeminal ganglion neurons were all predominantly small and medium-sized.
In the trigeminal ganglia, approximately 50% of CGRP-positive neurons were 5-HT1B
positive. Similarly, approximately 55% of CGRP-positive neurons were 5-HT1D immunoreactive.
Approximately 50% of CGRP-positive neurons were SP-positive, while 93% of SP-positive
neurons were CGRP-positive, suggesting that nearly all SP-positive neurons also
contain CGRP. The fibre types of the 5-HT1B- and 5-HT1D-positive neurons were
further investigated with an antibody against the A-fibre marker 200-kDa neurofilaments
(NF200). Approximately 46% of the 5-HT1B-positive and 43% of the 5-HT1D-positive
trigeminal ganglion neurons were also NF200 positive, indicating that many A-fibre
trigeminal neurons express 5-HT1B or 5-HT1D receptors. These results support the
hypothesis that one important action of antimigraine drugs is the inhibition of
CGRP release and that Adelta-fibres may play an important role in migraine pathogenesis."
E, Tajti J, Chadaide Z, Csillik B, Vecsei L.
of neuropeptides and nitric oxide synthase in the nerve fibers of the supratentorial
dura mater in an experimental migraine model.
Tech. 2001 May 1;53(3):193-211.
"The supratentorial cerebral dura of the
albino rat is equipped with a rich sensory innervation both in the connective
tissue and around blood vessels, which includes nociceptive axons and their terminals;
these display intense calcitonin gene-related peptide (CGRP) immunoreactivity.
Stereotactic electrical stimulation of the trigeminal (Gasserian) ganglion, regarded
as an experimental migraine model, caused marked increase and disintegration of
club-like perivascular CGRP-immunopositive nerve endings in the dura mater and
induced an apparent increase in the lengths of CGRP-immunoreactive axons. Intravenous
administration of sumatriptan or eletriptan, prior to electrical stimulation,
prevented disintegration of perivascular terminals and induced accumulation of
CGRP in terminal and preterminal portions of peripheral sensory axons. Consequently,
immunopositive terminals and varicosities increased in size; accumulation of axoplasmic
organelles resulted in the "hollow" appearence of numerous varicosities.
Since triptans exert their anti-migraine effect by virtue of agonist action on
5-HT(1D/B) receptors, we suggest that these drugs prevent the release of CGRP
from perivascular nerve terminals in the dura mater by an action at 5-HT(1D/B)
receptors. Nitroglycerine (NitroPOHL), given subcutaneously to rats, induces increased
beading of nitric oxide synthase (NOS)-immunoreactive nerve fibers in the supratentorial
cerebral dura mater, and an apparent increase in the number of NOS-immunoreactive
nerve fibers in the dural areas supplied by the anterior and middle meningeal
arteries, and the sinus sagittalis superior. Structural alterations of nitroxidergic
axons innervating blood vessels of the dura mater support the idea that nitric
oxide (NO) is involved in the induction of headache, a well-known side effect
of coronary dilator agents." [Abstract]
Goadsby PJ, Hoskin KL, Storer RJ, Edvinsson L, Connor
Adenosine A1 receptor agonists inhibit trigeminovascular nociceptive
Brain. 2002 Jun;125(Pt 6):1392-401.
is a considerable literature to suggest that adenosine A1 receptor agonists may
have anti-nociceptive effects, and we sought to explore the role of adenosine
A1 receptors in a model of trigeminovascular nociceptive transmission. Cats were
anaesthetized (alpha-chloralose 60 mg/kg, intraperitoneally), and prepared for
physiological monitoring. The superior sagittal sinus (SSS) was stimulated electrically,
and linked units were recorded in the trigeminocervical complex. Post-stimulus
histograms were constructed to analyse the responses and the effect of drug administration.
Blood was sampled from the external jugular vein to determine levels of calcitonin
gene-related peptide (CGRP) release before and after drug administration. Intravenous
administration of the highly selective adenosine A1 receptor agonist, GR79236
(3-100 microg/kg) had a dose-dependent inhibitory effect on SSS-evoked trigeminal
activity. The maximal effect (80 +/- 6% reduction in probability of firing) was
seen at 100 microg/kg. The neuronal inhibitory effect of GR79236 could be inhibited
by the selective adenosine A1 receptor antagonist DPCPX (300 microg/kg; P <
0.05). SSS stimulation increased cranial CGRP levels from 33 +/- 2 pmol/l (n =
6) to 64 +/- 3 pmol/l, an effect substantially reduced by pre-treatment with GR79236
(30 microg/kg; P < 0.01). The selective low efficacy adenosine A1 receptor
agonist, GR190178 (30-1000 microg/kg i.v.), also inhibited SSS-evoked neuronal
activity in a dose-dependent fashion. In this model of trigeminovascular nociception,
adenosine A1 receptor activation leads to neuronal inhibition without concomitant
vasoconstriction, suggesting a novel avenue for the treatment of migraine and
cluster headache." [Abstract]
Alan M., Sellers, Lynda A., Jenkins, David W., Jarvie, Emma M., Feniuk, Wasyl,
Humphrey, Patrick P. A.
Adenosine A1 Receptor-Mediated Inhibition
of Protein Kinase A-Induced Calcitonin Gene-Related Peptide Release from Rat Trigeminal
Mol Pharmacol 2001 59: 1533-1541
gene-related peptide (CGRP), a potent vasodilator, has been implicated in the
pathogenesis of migraine. Its release from adult rat trigeminal neurons in culture
was shown to be markedly increased by the activation of adenylate cyclase with
forskolin. Modulation of this secretion was investigated by a number of agents
with known inhibitory effects on cAMP generation mediated via receptor coupling
to G(i/o) proteins. Significantly, forskolin-stimulated CGRP release could be
closely correlated with the phosphorylation of the protein kinase A (PKA) substrate
cyclic AMP response element-binding protein (CREB). Forskolin-stimulated CGRP
release could be potently and effectively inhibited by the adenosine A(1) receptor-selective
agonist GR79236X (pIC(50) = 7.7 +/- 0.1, maximal inhibition 65 +/- 2.5% at 300
nM), whereas the A(2A) (CGS21680) and the A(3) (2-chloro-N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide)
receptor-selective agonists were without effect. GR79236X-mediated inhibition
was abolished by the A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine.
Immunocytochemical studies and Western analysis revealed the presence of adenosine
A(1) receptors on trigeminal neurons. However, despite the additional detection
of 5-hydroxytryptamine (5-HT)(1B) receptors on these cells, the clinically effective
antimigraine 5-HT(1B/1D) agonist sumatriptan did not inhibit forskolin-stimulated
CGRP release nor did it show any effect on the concomitant CREB phosphorylation.
In contrast, the mu-opioid agonist fentanyl elicited a 74 +/- 4% reduction in
CGRP levels. Forskolin-stimulated CGRP release and CREB phosphorylation could
be mimicked by incubation of the cells with chlorophenylthio-cAMP and blocked
by pretreatment with the PKA inhibitor myrPKI(14-22). Taken together, the present
data confirm the PKA-dependence of forskolin-stimulated CGRP release and suggest
that A(1) adenosine agonists may warrant further investigation in models of migraine
and neurogenic inflammation." [Full
Durham PL, Cady R, Cady R.
of calcitonin gene-related peptide secretion from trigeminal nerve cells by botulinum
toxin type A: implications for migraine therapy.
2004 Jan;44(1):35-42; discussion 42-3. [Abstract]
S, Williamson DJ, Goadsby PJ.
Voltage-dependent calcium channels
are involved in neurogenic dural vasodilatation via a presynaptic transmitter
Br J Pharmacol. 2003 Oct;140(3):558-66.
Epub 2003 Aug 26.
"A missense mutation of the CACNA1A gene that encodes
the alpha1A subunit of the voltage-dependent P/Q-type calcium channel has been
discovered in patients suffering from familial hemiplegic migraine. This suggested
that calcium channelopathies may be involved in migraine more broadly, and established
the importance of genetic mechanisms in migraine. Channelopathies share many clinical
characteristics with migraine, and thus exploring calcium channel functions in
the trigeminovascular system may give insights into migraine pathophysiology.
It is also known that drugs blocking the P/Q- and N-type calcium channels have
been successful in other animal models of trigeminovascular activation and head
pain. In the present study, we used intravital microscopy to examine the effects
of specific calcium channel blockers on neurogenic dural vasodilatation and calcitonin
gene-related peptide (CGRP)-induced dilation. The L-type voltage-dependent calcium
channel blocker calciseptine significantly attenuated (20 microg kg(-1), n=7)
the dilation brought about by electrical stimulation, but did not effect CGRP-induced
dural dilation. The P/Q-type voltage-dependent calcium channel blocker omega-agatoxin-IVA
(20 microg kg-1, n=7) significantly attenuated the dilation brought about by electrical
stimulation, but did not effect CGRP-induced dural dilation. The N-type voltage-dependent
calcium channel blocker omega-conotoxin-GVIA (20 microg kg(-1), n=8 and 40 microg
kg(-1), n=7) significantly attenuated the dilation brought about by electrical
stimulation, but did not effect CGRP-induced dural dilation. It is thought that
the P/Q-, N- and L-type calcium channels all exist presynaptically on trigeminovascular
neurons, and blockade of these channels prevents CGRP release, and, therefore,
dural blood vessel dilation. These data suggest that the P/Q-, N- and L-type calcium
channels may be involved in trigeminovascular nociception."