Buervenich S, Xiang F, Sydow O, Jonsson EG, Sedvall GC, Anvret M, Olson L.
Identification of four novel polymorphisms in the calcitonin/alpha-CGRP (CALCA) gene and an investigation of their possible associations with Parkinson disease, schizophrenia, and manic depression.
Hum Mutat 2001 May;17(5):435-6
"We identified novel polymorphisms in the calcitonin/CGRPalpha (CALCA) gene by direct sequencing of genomic DNA and subsequent genotyping by RFLP (restriction fragment length polymorphism) detection and investigated association with neurological or psychiatric disease. Four novel polymorphic alleles were found: two (g.979G>A and g.4218T>C) represented single nucleotide polymorphisms (SNPs), one consisted of two coupled SNPs in close vicinity to each other (g.1210T>C and g.1214C>G), and one was an intronic 16-bp microdeletion (2919-2934del16). One of the SNPs (g.4218T>C) causes a non-synonymous amino acid change (Leu66Pro) in the third exon, an exon common to both procalcitonin and pro-alpha-CGRP. In a subsequent association study, frequencies of the identified polymorphisms in Parkinson and schizophrenia patients were compared with frequencies in the normal population. No statistically significant association was found in our material. The 16-bp microdeletion polymorphism was present in a family with multiple cases of unipolar or bipolar depressive disorder. Using this polymorphism as marker, cosegregation with the phenotype was observed in the majority of individuals. Copyright 2001 Wiley-Liss, Inc." [Abstract]

OMIM - Online Mendelian Inheritance in Man: CALCA/CGRPalpha
[The CALCA gene has been located at 11p15.2-p15.1]

Craddock N, Lendon C.
Chromosome Workshop: chromosomes 11, 14, and 15.
Am J Med Genet 1999 Jun 18;88(3):244-54
"Two regions on chromosome 11, 11p15 in the region of tyrosine hydroxylase gene and 11q22-q23 in the region of DRD2, continue to retain some interest for functional psychosis." [Abstract]

De bruyn A, Mendelbaum K, Sandkuijl LA, Delvenne V, Hirsch D, Staner L, Mendlewicz J, Van Broeckhoven C.
Nonlinkage of bipolar illness to tyrosine hydroxylase, tyrosinase, and D2 and D4 dopamine receptor genes on chromosome 11.
Am J Psychiatry 1994 Jan;151(1):102-6
"OBJECTIVE: Previous linkage and allelic association studies using DNA polymorphisms, cosegregation of cytogenetic abnormalities with psychiatric illness, and assignment of genes involved in neutotransmitter metabolism suggested that chromosome 11 may harbor a gene predisposing to bipolar illness. The authors examined linkage in the families of 14 probands with bipolar illness, with the candidate genes tyrosine hydroxylase (TH), D4 dopamine receptor (DRD4) at 11p15, tyrosinase (TYR) at 11q14-q21, and D2 dopamine receptor (DRD2) at 11q22-q23, as well as with the c-Harvey-ras oncogene (HRAS) and insulin gene (INS), both located at 11p15, a region that previously showed linkage to bipolar illness. METHOD: The genetic data were analyzed with both lod score analysis (parametric) and affected-sib-pair analysis (nonparametric); both narrow and broad definitions of the clinical phenotype were used. Further influences of diagnostic uncertainties were accounted for by using diagnostic probability classes weighing the stability of each phenotype. RESULTS: Two-point linkage results excluded close linkage of bipolar illness to each candidate gene; negative results were also obtained when the narrow definition of the clinical phenotype was used. Moreover, multipoint linkage analysis of HRAS and INS excluded the 11p15 region encompassing both DRD4 and TH. In agreement with the negative linkage results, affected-sib-pair analysis did not show preferential sharing of marker alleles at any of the candidate genes. CONCLUSIONS: The negative results obtained under different genetic models exclude a frequent role for DRD4, TH, TYR, and DRD2 in the pathogenesis of bipolar illness." [Abstract]

McQuillin A, Lawrence J, Curtis D, Kalsi G, Smyth C, Hannesdottir S, Gurling H.
Adjacent genetic markers on chromosome 11p15.5 at or near the tyrosine hydroxylase locus that show population linkage disequilibrium with each other do not show allelic association with bipolar affective disorder.
Psychol Med 1999 Nov;29(6):1449-54
"BACKGROUND: Linkage and association studies have suggested genetic susceptibility to bipolar affective disorder in a region of chromosome 11 around the tyrosine hydroxylase locus. We attempted to test the hypothesis that there was allelic association between polymorphisms around the tyrosine hydroxylase locus and bipolar affective disorder. METHODS: A case-control association study was employed using four polymorphic markers, which span a region of approximately 2 cM across the tyrosine hydroxylase locus. RESULTS: No evidence for allelic association between bipolar affective disorder and any of these markers was found. However, linkage disequilibrium between the markers was detected. CONCLUSIONS: This finding diminishes the probability that genes in this region influence susceptibility to bipolar affective disorder, at least in our sample." [Abstract]

Vik A, Yatham LN.
Calcitonin and bipolar disorder: a hypothesis revisited.
J Psychiatry Neurosci 1998 Mar;23(2):109-17
"Double-blind trials conducted in the early 1980s showed that subcutaneous injections of salmon calcitonin in patients suffering from mania resulted in significant decreases in irritability, euphoria and hyperactivity. Although these results were promising, there were no follow-up studies in this area. A MEDLINE search into the effect of calcitonin on neuronal tissues revealed that calcitonin affects neuronal tissues in a manner similar to that of the currently accepted mood-stabilizing agents--namely by modulating intracellular second messenger signalling mechanisms, stabilizing neuronal membranes and inhibiting neuronal calcium influx. We suggest that these effects of calcitonin on neuronal tissues, combined with earlier clinical research showing its efficacy in treating the acute symptoms of mania, make calcitonin a candidate for further research in the treatment of bipolar disorder." [Abstract]

Carman JS, Wyatt RJ.
Calcium: bivalent cation in the bivalent psychoses.
Biol Psychiatry 1979 Apr;14(2):295-336
"Decreases in cerebrospinal fluid (CSF) calcium accompany mood elevation and motor activation in depressed patients undergoing treatment with ECT, lithium, and total sleep deprivation. Similarly, decreases in CSF calcium occur during acute psychotic agitation or mania. On the other hand, periodic recurrences of such agitated states are accompanied at their onset by transient increases in serum calcium and phosphorus. Several observations suggest that such serum ion shifts may trigger the more enduring and opposite shifts in CSF calcium and, in turn, the manic behavior. Progressive restriction of dietary calcium was earlier reported to mitigate and finally abolish both rhythmic rises in serum calcium and periodic agitated episodes in one psychotic patient. Lithium, which decreases the efficiency of alimentary calcium absorption, may function similarly. Conversely, a modest oral calcium lactate supplement (approximately one additional Recommended Daily Allowance of dietary calcium) seemed to slightly intensify agitation in six patients. Dihydrotachysterol (DHT), an analogue of vitamin D, which more exactly mimics the increase in both serum calcium and phosphorus, appeared in at least one periodically psychotic patient to trigger and opposite shift in CSF calcium. Moreover, in eight patients, manic symptomatology appeared de novo or grew significantly and substantially worse during 2 to 6 weeks of oral DHT administration. On the other hand, in 12 patients, subcutaneous injections of synthetic salmon calcitonin (SCT) decreased serum calcium and phosphorus, increased CSF calcium, and decreased agitation while augmenting depressive symptomatology. SCT also decreased quantified motor activity, frequency and severity of periodic agitated episodes, serum CPK and prolactin, and nocturnal sleep, while DHT or calcium lactate had opposite effects on the same parameters."
[Abstract]

Goltzman D, Mitchell J.
Interaction of calcitonin and calcitonin gene-related peptide at receptor sites in target tissues.
Science 1985 Mar 15;227(4692):1343-5
"Discrete receptor sites for calcitonin (CT) and calcitonin gene-related peptide (CGRP) were found in the nervous system and in peripheral tissues. Each peptide was capable of cross-reacting with the specific receptor of the other. In contrast to CT receptors, CGRP receptors were not linked to adenylate cyclase. However, CGRP could stimulate adenylate cyclase in CT target tissues apparently by interacting with CT receptors. The relative abilities of CGRP and mammalian CT to inhibit CT binding suggest that CGRP could serve as an endogenous ligand for CT receptors in the central nervous system." [Abstract]

Tiller-Borcich JK, Capili H, Gordan GS.
Human brain calcitonin gene-related peptide (CGRP) is concentrated in the locus caeruleus.
Neuropeptides 1988 Feb-Mar;11(2):55-61
"A quantitative survey of calcitonin gene-related peptide (CGRP) in brain, peripheral nerve and cerebrospinal fluid (CSF) was performed using radioimmunoassay (RIA) with antiserum against synthetic hCGRP. High levels (approximately 2000-15,000 fmol/mg protein) were found in the dorsal spinal cord, dorsal nerve and trigeminal nerve. Relatively large amounts (500-2000) were found in parts of the hypothalamic-pituitary axis, peripheral nerve and, for the first time, in the locus caeruleus. Low levels of CGRP (less than 500) were detected in the cerebrum, subcortical nuclei and cerebellum. CGRP, not previously reported in CSF, was detectable in all of 27 CSF specimens with mean values of 30 +/- 4.5 pmol/L (SE). Simultaneous plasma CGRP levels were higher and, when elevated by antihypertensive treatment were not increased in CSF, just as astronomical plasma levels of calcitonin in medullary carcinoma of the thyroid are not reflected in CSF. Our data confirm and extend the results of previous human and animal studies with evidence of species variation: humans have low CGRP levels in subcortical nuclei whereas high levels have been found in rat caudate-putamen and amygdala. The high level of CGRP in the locus caeruleus, the major source of noradrenergic neurotransmission in the CNS, is in harmony with the presumed functions of the LC and the very potent hemodynamic activity of CGRP." [Abstract]

Ehlers CL, Somes C, Li TK, Lumeng L, Hwang BH, Jimenez P, Mathe AA.
Calcitonin gene-related peptide (CGRP) levels and alcohol.
Int J Neuropsychopharmcol 1999 Sep;2(3):173-179
"Calcitonin gene-related peptide (CGRP) when administered into the brain exerts stress-like effects such as increased pain sensitivity, anorexia, and potentiation of fear-related behaviours. Since alcohol consumption may be related to alcohol's anxiolytic properties, the present study sought to determine if brain CGRP levels were correlated with genetic differences in preference for drinking alcohol and/or affected by alcohol exposure/withdrawal. CGRP-like immunoreactivity (CGRP-LI) was measured by radioimmunoassay (RIA) in amygdala, hippocampus, frontal cortex, hypothalamus, and caudate. In the first experiment, CGRP-LI was compared in alcohol-naive rats [preferring (P) and non-preferring (NP)], lower concentrations were found in the hippocampus (U = 153.5; d.f. = 1,28; p < 0.014) and frontal cortex (U = 183.0; d.f. = 1,28; p < 0.0001) of the P rats. In a second experiment, a group of outbred Wistar rats were exposed to alcohol in vapour chambers, or control conditions. At 7 wk of alcohol exposure there were no differences in exposed rats as compared to controls. However, at 4 wk following ethanol withdrawal, higher concentrations of CGRP-LI were found in the hippocampus (U = 26.5; d.f. = 1,20 p < 0.05), hypothalamus (U = 17.5; d.f. = 1,20; p < 0.009), and caudate-putamen (U = 17.0; d.f. = 1,20; p < 0.009) of the previously exposed animals. These studies suggest that CGRP may modulate alcohol preference and additionally, that exposure/withdrawal from ethanol produces long-lasting effects on CGRP-LI." [Abstract]

Kocorowski LH, Helmstetter FJ.
Calcitonin gene-related peptide released within the amygdala is involved in Pavlovian auditory fear conditioning.
Neurobiol Learn Mem 2001 Mar;75(2):149-63
"The effects of CGRP and the CGRP receptor antagonist hCGRP(8-37) injected into the amygdala on both the acquisition and expression of fear behavior to a discrete auditory conditional stimulus (CS) and the training context were assessed. In Experiment 1, pretraining injections of CGRP but not hCGRP(8-37) produced fear-like behavior before any aversive stimuli were presented. While both compounds attenuated freezing to the contextual CS on the test day, neither affected learning about the auditory CS. In Experiment 2, pretesting injections of hCGRP(8-37) (0.63 mM) selectively attenuated freezing to the auditory CS but left freezing to the contextual CS intact. These data suggest that CGRP in the amygdala may selectively contribute to the expression of learning about auditory stimuli during fear conditioning. Copyright 2001 Academic Press." [Abstract]

Iino K, Oki Y, Tominaga T, Iwabuchi M, Ozawa M, Watanabe F, Yoshimi T.
Stimulatory effect of calcitonin gene-related peptide on adrenocorticotropin release from rat anterior pituitary cells.
J Neuroendocrinol 1998 May;10(5):325-9
"In the present study, we examined the direct regulatory effect of rat calcitonin gene-related peptide (CGRP) on adrenocorticotropin (ACTH) release from rat cultured anterior pituitary cells. CGRP significantly increased ACTH release at concentrations of 10(-8)-10(-11) M. The ACTH release was gradually increased by CGRP concentrations lower than 10(-10) M, and was decreased at concentrations higher than 10(-9) M, presenting a bell-shaped dose-response curve. As well as having an additive effect on corticotropin-releasing factor-induced ACTH release, CGRP stimulated the accumulation of intracellular cAMP. The CGRP-induced ACTH release was inhibited by a protein kinase A inhibitor, suggesting that its stimulatory effect on the ACTH release was mediated via an adenylate-cyclase-protein kinase system. CGRP-like immunoreactive nerve fibers have been reported to innervate the anterior pituitary, so that the stimulatory effect of CGRP on the ACTH release suggests that this peptide may be involved in neural regulation of hormone secretion in the anterior pituitary." [Abstract]

David P. Spratt, and Allan E. Herbison
Sexually Dimorphic Effects of Testosterone on Preoptic Area Calcitonin Gene-Related Peptide mRNA Expression Depend upon Neuron Location and Differential Estrogen and Androgen Receptor Activation
Endocrinology 142: 3397-3404
"Experiments examined activational roles of gonadal steroids on the sexually dimorphic, calcitonin gene-related peptide-expressing neurons of the rat preoptic area. Gonadectomy of male rats followed by treatment with testosterone, dihydrotestosterone, or estrogen demonstrated that the tonic suppressive influence of testosterone on cellular levels of calcitonin gene-related peptide mRNA expression in the medial preoptic nucleus and anteroventral periventricular nucleus occurred through either ER- or AR-mediated mechanisms (P < 0.05). The gonadectomy of adult female rats demonstrated little tonic influence of ovarian steroids upon calcitonin gene-related peptide mRNA levels. However, the administration of male levels of testosterone to ovariectomized rats resulted in reduced calcitonin gene-related peptide mRNA expression within the medial preoptic nucleus (P < 0.05) and, strikingly, a 3-fold induction in calcitonin gene-related peptide mRNA expression in the anteroventral periventricular nucleus (P < 0.01). Testosterone’s effects in the medial preoptic nucleus and anteroventral periventricular nucleus of the female required both ER and AR activation. Dual labeling immunocytochemical studies revealed that less than 10% of calcitonin gene-related peptide neurons in the male expressed ARs compared with approximately 50% in the female. These investigations reveal that sexually differentiated region- and steroid receptor-specific mechanisms function in association with the sex differences in circulating gonadal steroids to maintain the sexually dimorphic nature of calcitonin gene-related peptide expression in the preoptic area of the adult rat." [Full Text]

Leclercq P, Herbison AE.
Sexually dimorphic expression of calcitonin gene-related peptide (CGRP) immunoreactivity by rat mediobasal hypothalamic neurons.
J Comp Neurol 1996 Apr 8;367(3):444-53
"Although the hypothalamic arcuate nucleus is a sexually dimorphic region of the rat brain, there are no reports of sex differences in the number of neurons containing specific neuropeptides within this structure. As cells synthesizing calcitonin gene-related peptide (CGRP) have been shown to exhibit sex differences in other steroid-receptive regions of the rat brain, we examined whether the CGRP-immunoreactive cells located in the mediobasal hypothalamus may also be sexually dimorphic. Immunostaining of sections from male and female colchicine-treated rats revealed a small population of CGRP-immunoreactive cells distributed throughout the arcuate nucleus. Immunoreactive cells were also detected in the lateral hypothalamic perifornical region, dorsomedial, posterior periventricular and ventral tuberomammillary nuclei, and zona incerta. Cell count analysis revealed approximately twice as many CGRP-immunoreactive cell profiles in the rostral (P < 0.01), middle (P < 0.001), and caudal (P < 0.01) thirds of the arcuate nucleus of male rats compared with females. A significant sex difference in immunoreactive cell numbers (male > female) was also detected within the caudal dorsomedial nucleus (P < 0.05) but not in the posterior periventricular nucleus, perifornical region and zona incerta. Although fibers immunoreactive for CGRP were identified in low density throughout the mediobasal hypothalamus, only female rats displayed prominent fiber staining in the periventricular region. Double-labelling immunofluorescence experiments revealed that the CGRP-immunoreactive cells within the zona incerta, but not the hypothalamus, were also immunoreactive for tyrosine hydroxylase; at least 60% of the A13 dopaminergic neurons co-express CGRP. These results provide evidence that sex differences exist in the number of specific neuropeptide-synthesizing cells within the hypothalamic arcuate nucleus and provide further examples of cell populations expressing CGRP immunoreactivity in a sexually dimorphic manner." [Abstract]

van Rossum D, Hanisch UK, Quirion R.
Neuroanatomical localization, pharmacological characterization and functions of CGRP, related peptides and their receptors.
Neurosci Biobehav Rev 1997 Sep;21(5):649-78
"Calcitonin generelated peptide (CGRP) is a neuropeptide discovered by a molecular approach over 10 years ago. More recently, islet amyloid polypeptide or amylin, and adrenomedullin were isolated from human insulinoma and pheochromocytoma respectively, and revealed between 25 and 50% sequence homology with CGRP. This review discusses findings on the anatomical distributions of CGRP mRNA, CGRP-like immunoreactivity and receptors in the central nervous system, as well as the potential physiological roles for CGRP. The anatomical distribution and biological activities of amylin and adrenomedullin are also presented. Based upon the differential biological activity of various CGRP analogs, the CGRP receptors have been classified in two major classes, namely the CGRP1 and CGRP2 subtypes. A third subtype has also been proposed (e.g. in the nucleus accumbens) as it does not share the pharmacological properties of the other two classes. The anatomical distribution and the pharmacological characteristics of amylin binding sites in the rat brain are different from those reported for CGRP but share several similarities with the salmon calcitonin receptors. The receptors identified thus far for CGRP and related peptides belong to the G protein-coupled receptor superfamily. Indeed, modulation of adenylate cyclase activity following receptor activation has been reported for CGRP, amylin and adrenomedullin. Furthermore, the binding affinity of CGRP and related peptides is modulated by nucleotides such as GTP. The cloning of various calcitonin and most recently of CGRP1 and adrenomedullin receptors was reported and revealed structural similarities but also significant differences to other members of the G protein-coupled receptors. They may thus form a new subfamily. The cloning of the amylin receptor(s) as well as of the other putative CGRP receptor subtype(s) are still awaited. Finally, a broad variety of biological activities has been described for CGRP-like peptides. These include vasodilation, nociception, glucose uptake and the stimulation of glycolysis in skeletal muscles. These effects may thus suggest their potential role and therapeutic applications in migraine, subarachnoid haemorrhage, diabetes and pain-related mechanisms, among other disorders." [Abstract]

Poore LH, Helmstetter FJ.
The effects of central injections of calcitonin gene-related peptide on fear-related behavior.
Neurobiol Learn Mem 1996 Sep;66(2):241-5
"Calcitonin gene-related peptide (CGRP) has been localized in several regions of the rat brain that are known to be important for the expression of fear responses. Some evidence suggests that CGRP may act as a neurotransmitter at synapses that are believed to be important for aversive learning. In the present study, male rats were prepared with intracerebroventricular cannulae and injected with CGRP during different phases of training and testing when a distinctive environment was paired with foot shock. When injected prior to training, CGRP directly evoked fear-related behavior and postshock freezing. When pretreated with CGRP and exposed to the shock-associated environment 24 h after training rats again showed an enhanced fear response. These results support the idea that this peptide functions as a neurotransmitter at central synapses which are important for the expression of fear." [Abstract]

Hasegawa T, Yokotani K, Okuma Y, Manabe M, Hirakawa M, Osumi Y.
Microinjection of alpha-calcitonin gene-related peptide into the hypothalamus activates sympathetic outflow in rats.
Jpn J Pharmacol 1993 Apr;61(4):325-32
"Effect of rat alpha-calcitonin gene-related peptide (alpha-CGRP) microinjected into various hypothalamic nuclei on plasma levels of catecholamines and arterial blood pressure were investigated in urethane-anesthetized rats. alpha-CGRP (0.05 and 0.25 nmol) microinjected into the hypothalamic paraventricular nucleus (PVN) increased the plasma level of noradrenaline (NA), but not that of adrenaline (AD), in a dose-dependent manner. A similar increase in plasma level of NA was also observed by alpha-CGRP (0.05 nmol) microinjected into the preoptic area (POA), anterior hypothalamus (AH), dorsomedial hypothalamus (DMH) and ventromedial hypothalamus (VMH). A significant increase in arterial blood pressure was observed by microinjection of alpha-CGRP (0.05 nmol) into the PVN, POA, AH and DMH, and the most prominent increase was caused by its microinjection into the PVN. Microinjection of the same dose of this peptide into the VMH, lateral hypothalamic area and posterior hypothalamus was without effect. The increase in plasma level of NA induced by alpha-CGRP (0.05 nmol) into the PVN was not affected by bilateral adrenalectomy. Electrical stimulation of the PVN elicited increases in plasma levels of both NA and AD. This increase in NA was abolished by chemical sympathectomy with 6-hydroxydopamine (50 mg/kg, i.v., 3 days before experiments). These results suggest that activation of the PVN by electrical stimulation elicits both sympathetic and adrenomedullary outflow. alpha-CGRP microinjected into the PVN selectively activates the sympathetic outflow." [Abstract]

Welch SP, Bass PP, Olson KG, Pugh G.
Morphine-induced modulation of calcitonin gene-related peptide levels.
Pharmacol Biochem Behav 1992 Dec;43(4):1107-16
"Calcitonin gene-related peptide (CGRP) is a novel calcium-modulatory product of the gene that encodes for calcitonin. Acute administration of morphine decreases levels of CGRP in rat corpus striatum. Tolerance to morphine did not alter the levels of CGRP in any brain region or in the spinal cord of the rat. CGRP did not alter the tolerance to the antinociceptive effects of morphine. Chronic naltrexone increased the levels of CGRP in the hypothalamus. Concurrent chronic administration of naltrexone plus morphine raised the levels of CGRP in the medulla, midbrain, and spinal cord. CGRP enhances naloxone-precipitated withdrawal jumping in mice. In rats, during withdrawal the levels of CGRP were tripled in the corpus striatum and significantly reduced in the hippocampus and hypothalamus. In the corpus striatum, CGRP enhances forskolin-stimulated cyclic adenosine monophosphate (cAMP) accumulation when such accumulation is suppressed (as with the chronic opiate administration), but conversely depresses forskolin-stimulated cAMP accumulation under normal conditions (as with chronic vehicle administration). These data are consistent with the hypothesis that CGRP acts as a modulatory peptide in opiate-sensitive systems and tonic opioid control of CGRP levels exists in brain." [Abstract]

Dennis T, Fournier A, Guard S, St Pierre S, Quirion R.
Calcitonin gene-related peptide (hCGRP alpha) binding sites in the nucleus accumbens. Atypical structural requirements and marked phylogenic differences.
Brain Res 1991 Jan 18;539(1):59-66
"The distribution of [125I]hCGRP alpha binding sites was studied in tissue sections from rat brain and, at the level of the nucleus accumbens in the brains of 6 other species. In the rat, very high levels of binding were found in the nucleus accumbens, the amygdaloid complex and mammillary body while high amounts were localized to the superficial layers of the superior colliculus, temporal cortex, cerebellum (molecular layer), frontal cortex and inferior olive. Moderate densities of [125I]hCGRP alpha binding were observed in the medial geniculate nucleus, inferior colliculus and substantia nigra. Regional competition studies in rat brain showed that salmon calcitonin was almost as effective as hCGRP alpha in competing for [125I]hCGRP alpha binding sites in the nucleus accumbens but was mostly inactive in other regions such as the mesolimbic cortex and the striatum. On the basis of their atypical sensitivity to salmon calcitonin, [125I]hCGRP alpha binding sites in the rat nucleus accumbens, which appear between postnatal days 4 and 7, do not seem to correspond to either the CGRP1 or CGRP2 receptor subtypes. Marked species differences were observed in the distribution of [125I]hCGRP alpha binding sites, especially in the nucleus accumbens. In the mouse, low densities of hCGRP alpha sites were observed in striatum and fronto-parietal cortex while low to moderate levels were found in the medial and posterior aspects of the nucleus accumbens. A similar distribution was seen in the guinea pig brain albeit of generally higher density. In the rat, very high amounts of [125I]hCGRP alpha binding were seen in the nucleus accumbens while lower levels were found in the striatum and certain cortical areas." [Abstract]

Kenji Kuwasako, Yoshiyuki Shimekake, Michitaka Masuda, Koichiro Nakahara, Tetsuya Yoshida, Motoji Kitaura, Kazuo Kitamura, Tanenao Eto, and Tsuneaki Sakata
Visualization of the Calcitonin Receptor-like Receptor and Its Receptor Activity-modifying Proteins during Internalization and Recycling
J. Biol. Chem. 275: 29602-29609, 2000. [Full Text]

Durham, Paul L., Russo, Andrew F.
Regulation of Calcitonin Gene-Related Peptide Secretion by a Serotonergic Antimigraine Drug
J. 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 Text]

Takahashi K, Mouri T, Sone M, Murakami O, Itoi K, Imai Y, Ohneda M, Yoshinaga K, Sasano N.
Calcitonin gene-related peptide in the human hypothalamus.
Endocrinol Jpn 1989 Jun;36(3):409-15
"Calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) in the human hypothalamus was investigated by radioimmunoassay and by immunocytochemistry. CGRP-LI was detected from two hypothalami obtained at autopsy (2.1 and 7.0 ng/g wet tissue) by radioimmunoassay. Reverse phase high performance liquid chromatography revealed that most of the CGRP-LI in the human hypothalamus was eluted in an identical position with synthetic human CGRP. For immunocytochemistry, human hypothalami obtained at autopsy were fixed and cryostat-sectioned at 40 microns. Free floating sections were immunostained with antibody to CGRP. CGRP-immunoreactive cell bodies were found in the supraoptic nucleus, paraventricular nucleus and infundibular nucleus. These findings indicate that CGRP exists in the cell bodies of the supraoptic nucleus, paraventricular nucleus and infundibular nucleus in the human hypothalamus and CGRP may play some roles in the endocrine and other functions of the human hypothalamus." [Abstract]

Paues J, Engblom D, Mackerlova L, Ericsson-Dahlstrand A, Blomqvist A.
Feeding-related immune responsive brain stem neurons: association with CGRP.
Neuroreport 2001 Aug 8;12(11):2399-403
"Using dual-labeling in situ hybridization histochemistry, the neurotransmitter expression of immune-responsive neurons in the pontine parabrachial nucleus, a major relay for interoceptive information, was investigated. Intravenous injection of bacterial wall lipopolysaccharide resulted in dense c-fos mRNA expression in the external lateral parabrachial nucleus, and a majority of the c-fos expressing cells also expressed calcitonin gene-related peptide (CGRP) mRNA. In contrast CGRP-positive cells in the adjoining external medial subnucleus were c-fos negative. Taken together with previous hodological and behavioral studies, these data suggest that CGRPergic parabrachial neurons may mediate lipopolysaccharide-induced anorexia by means of their projection to central nucleus of the amygdala." [Abstract]

Poyner, David R., Sexton, Patrick M., Marshall, Ian, Smith, David M., Quirion, Remi, Born, Walter, Muff, Roman, Fischer, Jan A., Foord, Steven M.
International Union of Pharmacology. XXXII. The Mammalian Calcitonin Gene-Related Peptides, Adrenomedullin, Amylin, and Calcitonin Receptors
Pharmacol Rev 2002 54: 233-246 [Full Text]

Mathe AA, Jousisto-Hanson J, Stenfors C, Theodorsson E.
Effect of lithium on tachykinins, calcitonin gene-related peptide, and neuropeptide Y in rat brain.
J Neurosci Res 1990 Jun;26(2):233-7
"The effects of lithium on brain regional concentrations of substance P (SP)-, neurokinin A (NKA)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivities (-LI) were studied in rat. In the pilot study, rats were divided into three groups that were administered vehicle, or 1 or 4 mEq/kg lithium sulphate, respectively, intraperitoneally once/day for 9 days. In the second experiment, rats were divided into three groups receiving vehicle, or 1 or 2 mEq/kg lithium sulphate, respectively, intraperitoneally twice/day for 9 days. After sacrifice by focused microwave irradiation, brains were dissected, weighed, and frozen. Peptides were extracted and measured in extract aliquots by specific radioimmunoassays. Marked regional differences (P less than .001) were found for each of the peptides measured. In the pilot study the higher lithium dose, 4 mEq/kg, significantly raised neuropeptide levels. However, animals receiving this dose also showed signs of toxicity. In the second experiment, lithium increased SP-LI concentrations in striatum and hypothalamus (72 and 29%, P's less than .001 and .05). NKA-LI was also elevated in striatum (44%, P less than .01). CGRP-LI, in parallel to SP-LI, was increased in striatum and hypothalamus (58 and 78%, P's less than .05 and .01). In contrast, lithium decreased CGRP-LI in the pituitary gland (56%, P less than .01). NPY-LI was increased in striatum, and frontal and occipital cortex (30, 66, and 60%, respectively; P's less than .01, .01, and .05)." [Abstract]

Deutch AY, Roth RH.
Calcitonin gene-related peptide in the ventral tegmental area: selective modulation of prefrontal cortical dopamine metabolism.
Neurosci Lett 1987 Feb 24;74(2):169-74
"The distribution of calcitonin gene-related peptide (CGRP) in the A10 dopamine (DA) cell group region of the ventral tegmental area (VTA) of the rat was examined using immunohistochemical techniques. CGRP-like immunoreactivity was localized to axons innervating the rostral and dorsal VTA. Direct administration of CGRP to the VTA of the rat resulted in a dose-related increase in DA utilization in the medial prefrontal cortex, but not other mesocortical, mesolimbic, or striatal DA terminal field regions. These data suggest that CGRP may function to selectively modulate the activity of VTA dopaminergic neurons which innervate the prefrontal cortex." [Abstract]

Durham, Paul L., Sharma, Ram V., Russo, Andrew F.
Repression of the Calcitonin Gene-Related Peptide Promoter by 5-HT1 Receptor Activation
J. Neurosci. 1997 17: 9545-9553
"We have investigated the control of calcitonin gene-related peptide (CGRP) expression by a serotonergic agonist that is related pharmacologically to currently used antimigraine drugs. During migraines, CGRP levels are elevated but then returned to normal by a 5-HT1 receptor agonist, sumatriptan. However, neither the molecular nor cellular targets of this drug are known. Trigeminal neurons are the major source of cerebrovascular CGRP, and thus we have used trigeminal primary cultures and the neuronal-like CA77 thyroid C-cell line as a model. We first demonstrate that sumatriptan and another 5-HT1 agonist, CGS 12066A (CGS), cause a robust and prolonged increase with oscillations in intracellular calcium in CA77 cells. CGS caused a similar increase in trigeminal cultures. We then show that CGS treatment leads to a decrease in CGRP mRNA levels in the CA77 cells. This decrease is attributable to the repression of promoter activity through two discrete elements: (1) the cAMP-responsive region, via a cAMP-independent mechanism; and (2) the cell-specific enhancer, which binds the upstream stimulatory factor helix-loop-helix protein and a cell-specific activator. These results demonstrate that activation of the endogenous 5-HT1 receptor is coupled to calcium signaling pathways and leads to inhibition of CGRP gene transcription." [Full Text]

Paul L. Durham, and Andrew F. Russo
Serotonergic Repression of Mitogen-Activated Protein Kinase Control of the Calcitonin Gene-Related Peptide Enhancer
Mol. Endocrinol. 12: 1002-1009, 1998.
"We have investigated the mechanisms underlying regulation of the calcitonin gene-related peptide (CGRP) cell-specific enhancer. Recently, we reported that this enhancer is inhibited by serotonin type-1 (5-HT1) agonists, similar to currently used antimigraine drugs. We have now tested whether this repression involves a mitogen-activated protein (MAP) kinase pathway. We first demonstrate that the CGRP enhancer is strongly (10-fold) activated by a constitutively active MAP kinase kinase (MEK1), yielding reporter activities 100-fold above the enhancerless control. The involvement of a MAP kinase pathway was confirmed by down-regulation of reporter activity upon cotransfection of a dominant negative Ras. Activation of the enhancer by MEK1 was blocked in a dose-dependent manner by the 5-HT1 receptor agonist CGS 12066A (CGS). Since it is not known whether the CGRP enhancer factors are immediate targets of MAP kinases, we then used Elk-1- and c-Jun-dependent reporter genes that are directly activated by the ERK (extracellular signal-regulated kinases) and JNK (c-Jun N-terminal kinase) MAP kinases. CGS treatment repressed the activation of both of these reporters, suggesting that at least two MAP kinases are the immediate targets of CGS-mediated repression. We further demonstrate that 5-HT1 agonists inactivate ERK by dephosphorylation, even in the presence of constitutively activated MEK1. This inactivation appears to be due to a marked increase in the level of MAP kinase phosphatase-1. These results have defined a novel and general mechanism by which 5-HT1 receptor agonists can repress MAP kinase activation of target genes, such as CGRP." [Full Text]

Angelucci F, Gruber SH, Mathe AA.
A pilot study of rat brain regional distribution of calcitonin, katacalcin and calcitonin gene-related peptide before andafter antipsychotic treatment.
Neuropeptides 2001 Oct;35(5-6):285-91
"In contrast to extensive determinations of calcitonin gene-related peptide (CGRP) in neural tissues, calcitonin and its carboxyl-terminal flanking peptide katacalcin (in human PDN-21) have not been systematically measured by radioimmunoassay (RIA) in discrete brain structures. Using microwave irradiation (MW), a procedure that increases the recovery of neuropeptides, we investigated by radioimmunoassay (RIA) the rat brain regional distribution of CGRP like- immunoreactivity (-LI), calcitonin-LI, and katacalcin-LI. Calcitonin-LI and katacalcin-LI were found in low concentrations in frontal cortex, occipital cortex, striatum and hippocampus. Moreover, a 4-week treatment with antipsychotic drugs altered the concentrations of the calcitonin-gene family peptides in the frontal cortex, occipital cortex, and hippocampus; the magnitude of these changes, however, was only moderate. Lastly, calcitonin-LI and katacalcin-LI baseline concentrations as well as after antipsychotic treatment were highly correlated in the frontal cortex, striatum, and hippocampus. The possible regulatory role of calcitonin gene family peptides in the central nervous system (CNS) needs to be further explored. Copyright 2001 Harcourt Publishers Ltd." [Abstract]

Husum H, Termeer E, Mathe AA, Bolwig TG, Ellenbroek BA.
Early maternal deprivation alters hippocampal levels of neuropeptide Y and calcitonin-gene related peptide in adult rats.
Neuropharmacology 2002 May;42(6):798-806
"Stressful events early in life are reported to be more prevalent among patients with an adult life psychiatric disorder. Early maternal deprivation is considered an animal model of early life stress. Maternally deprived adult rats display long-term alterations in the neuroendocrine system, brain and behavior that are in many ways analogous to depressive and schizophrenic symptomatology. Neuropeptide Y (NPY) and calcitonin-gene related peptide (CGRP) have been implicated in both disorders and also been suggested to play a role in the neuroadaptational response to stress. Consequently, male Wistar rat-pups were subjected to early maternal deprivation or control handling, on postnatal day (pnd) 9. On pnd 21, pups were weaned and split into two groups that were reared either on a saw-dust floor or on a grid-floor, considered to be a mild stressor. On pnd 67, all animals were subjected to the prepulse inhibition test. One week later, the animals were sacrificed, the brains removed and dissected on ice. Levels of NPY-like immunoreactivity (LI) and CGRP-LI were quantified by radioimmunoassay in brain regional extracts. Maternal deprivation led to a significant reduction in basal startle amplitude and disruption of prepulse inhibition. These findings were paralleled by significantly reduced levels of NPY and CGRP in the hippocampus and occipital cortex. It is hypothesised that these changes may be of relevance to aspects of schizophrenic and affective symptomatology. The present study further shows that brain NPY and, in particular, CGRP are sensitive to long-term mild stress and further implicate the involvement of these peptides in the neuroendocrine stress response." [Abstract]

Mathe AA, Agren H, Lindstrom L, Theodorsson E.
Increased concentration of calcitonin gene-related peptide in cerebrospinal fluid of depressed patients. A possible trait marker of major depressive disorder.
Neurosci Lett 1994 Dec 5;182(2):138-42
"Cerebrospinal fluid (CSF) was collected under controlled conditions from subjects suffering from major depression (n = 63) or schizophrenia (n = 28) and from healthy controls (n = 20). Following Sep-pak extraction, calcitonin gene-related peptide immunoreactivity (CGRP-LI) was determined by radioimmunoassay in sample aliquots. CGRP-LI concentrations in CSF were increased in the depressed patients compared to the schizophrenic and control subjects (P < 0.001). No CGRP-LI differences were found between the latter two groups. CGRP-LI did not correlate to any of the technical (e.g. storage conditions) or patient (demographic, biochemical, or clinical) variables investigated. In view of the CGRP's discrete distribution and specific effects in brain and the above results, we hypothesize that increased CSF CGRP-LI might be a trait marker of major depression. Regardless of the mechanisms (altered synthesis/release/metabolism in brain or changed fate in CSF) leading to elevated CSF CGRP-LI, the identification of a possible disease trait marker should contribute to the early diagnosis of major depression and identification of family members at risk and may help in differential diagnosis in other disorders with affective symptomatology." [Abstract]

Guidobono F, Netti C, Pecile A, Gritti I, Mancia M.
Stress-related changes in calcitonin gene-related peptide binding sites in the cat central nervous system.
Neuropeptides 1991 May;19(1):57-63
"The possibility of area-specific changes in binding sites for CGRP in response to stress was studied in cat CNS after repeated sleep-deprivation and restriction of movement. Brain sections were obtained from a cat placed under stressful conditions for 2 h the 1st day, 6 h the 2nd day and 24 h the 3rd day. Changes in CGRP binding sites were evaluated by an in vitro autoradiographic technique with 125I-Tyr-rat-CGRP as a ligand. The autoradiograms were then compared with those of control animals. The results show decreased labelling in the cortex prefrontalis and pyriformis and in some basal ganglia (n. caudatus, claustrum, n. entopedencularis). Increased CGRP binding site densities were seen in areas involved in the integration of sensory information, in the control of endocrine secretion and in those that participate in sleep-walking cycles. These changes in CGRP binding in selective CNS areas following stress suggests that CGRP plays a role in processes of adaptation." [Abstract]

Rosenfeld MG, Mermod JJ, Amara SG, Swanson LW, Sawchenko PE, Rivier J, Vale WW, Evans RM.
Production of a novel neuropeptide encoded by the calcitonin gene via tissue-specific RNA processing.
Nature 1983 Jul 14-20;304(5922):129-35
"Alternative processing of the RNA transcribed from the calcitonin gene appears to result in the production of a messenger RNA in neural tissue distinct from that in thyroidal 'C' cells. The thyroid mRNA encodes a precursor to the hormone calcitonin whereas that in neural tissues generates a novel neuropeptide, referred to as calcitonin gene-related peptide (CGRP). The distribution of CGRP-producing cells and pathways in the brain and other tissues suggests functions for the peptide in nociception, ingestive behaviour and modulation of the autonomic and endocrine systems." [Abstract]

Tschopp FA, Henke H, Petermann JB, Tobler PH, Janzer R, Hokfelt T, Lundberg JM, Cuello C, Fischer JA.
Calcitonin gene-related peptide and its binding sites in the human central nervous system and pituitary.
Proc Natl Acad Sci U S A 1985 Jan;82(1):248-52
"Binding sites for synthetic human 125I-labeled calcitonin gene-related peptide (125I-CGRP) have been demonstrated in membranes of the human nervous system. Binding was high in the cerebellar cortex (1.35 +/- 0.27 fmol/mg of tissue; mean +/- SEM), spinal cord (1.06 +/- 0.27 to 1.27 +/- 0.23 fmol/mg), and nucleus dentatus (1.02 +/- 0.15 fmol/mg), intermediate in the inferior colliculus (0.80 +/- 0.14 fmol/mg) and substantia nigra (0.75 +/- 0.14 fmol/mg), low in the neocortex, globus pallidus, nucleus caudatus, hippocampus, amygdala, superior colliculus, thalamus, and hypothalamus (0.15-0.32 fmol/mg), and negligible in spinal and sympathetic ganglia and pituitary (less than 0.04 fmol/mg). Autoradiography showed distinct 125I-CGRP binding over the molecular and Purkinje cell layers of the cerebellar cortex and over the substantia gelatinosa posterior of the spinal cord. The highest levels of CGRP-like components were recognized in the dorsal part of the spinal cord and the pituitary gland. In the ventral part of the spinal cord as well as in the pituitary and thyroid glands, CGRP values were higher when measured by radioreceptorassay as compared to RIA, indicating that at least two CGRP-like components are present. The predominant CGRP-like peak on HPLC had the retention time of synthetic human CGRP. Immunohistochemistry revealed the presence of a dense plexus of CGRP immunoreactive nerve fibers in the dorsal horn of the spinal cord." [Abstract]

Maneuf YP, McKnight AT.
Calcitonin gene-related peptide-mediated increase in K(+)-induced [(3)H]-dopamine release from rat caudal striatal slices.
Neurosci Lett 2001 Sep 14;310(2-3):73-6
"The calcitonin-gene receptor peptide (alphaCGRP) receptor is present in high levels in the caudal striatum of the rat. Previous behavioural experiments have highlighted a possible correlation between alphaCGRP-mediated effects and the dopaminergic system. In this study, we examined the effect of alphaCGRP on K(+)-evoked [(3)H]-dopamine release in a slice preparation of the rat caudal striatum. The unstimulated release of [(3)H]-dopamine was not affected by alphaCGRP. However, alphaCGRP increased the release of [(3)H]-dopamine evoked by K(+) (30 mM) in a concentration-dependent manner. The stimulatory effect of alphaCGRP was blocked by the CGRP1 antagonist hCGRP(8-37) (without effect on its own). The stimulatory effect of 1 microM alphaCGRP was blocked by dizocilpine (MK-801), suggesting that excitatory transmission is involved in mediating the facilitated release. This study suggests that the peptide alphaCGRP, modulates dopamine release in the rat caudal striatum probably indirectly via glutamatergic transmission." [Abstract]

Kozicz T, Arimura A.
Axon terminals containing CGRP-immunoreactivity form synapses with CRF- and Met-enkephalin-immunopositive neurons in the laterodorsal division of the bed nucleus of the stria terminalis in the rat.
Brain Res 2001 Mar 2;893(1-2):11-20
"The lateral division of the bed nucleus of the stria terminalis (BSTL) is an important forebrain structure that relays information between limbic structures and the hypothalamus. The BSTL displays a very dense calcitonin gene-related peptide-immunoreactive (-ir) fiber terminal network, and contains a substantial number of the corticotropin releasing factor (CRF)-ir neurons. Several Met-enkephalin-ir perikarya have also been observed in the BSTL. The distributions of CRF- and Met-enkephalin-ir neurons and that of the calcitonin gene-related peptide (CGRP)-ir axon terminals overlap within the BSTL, suggesting synaptic connections between CRF- and Met-enkephalin-ir neurons and axon terminals immunoreactive for CGRP. Double staining immunohistochemistry revealed that CGRP-ir axon terminals were within close proximity to dendrites or perikarya of corticotropin releasing factor and Met-enkephalin-ir neurons. When viewed at the electron microscopic level, axodendritic or axosomatic synapses between CGRP-ir fiber terminals and neurons immunoreactive for CRF and Met-enkephalin were detected. Most of the CRF-ir neurons project to brainstem centers, which modulate the physiological changes accompanying stress, whereas the Met-enkephalin-ir perikarya are most likely interneurons that often colocalize with GABA. The parabrachial nucleus, a vital autonomic center, is the primary source of CGRP-ir fiber terminals to the BSTL. The synaptic contacts between the CGRP axon terminals and CRF- and Met-enkephalin-ir neurons underlie the importance of connections between autonomic brainstem centers and BSTL, which can be fundamental in the modulatory control of endocrine, physiological and behavioral responses during stress." [Abstract]

Moreno MJ, Cohen Z, Stanimirovic DB, Hamel E.
Functional calcitonin gene-related peptide type 1 and adrenomedullin receptors in human trigeminal ganglia, brain vessels, and cerebromicrovascular or astroglial cells in culture.
J Cereb Blood Flow Metab 1999 Nov;19(11):1270-8
"Calcitonin gene-related peptide (CGRP) and adrenomedullin (ADM) are potent dilators of human brain arteries, and they have been implicated in the neurogenic inflammation underlying migraine headache and in the evolution of stroke, respectively. However, little is known about the presynaptic and postsynaptic distribution of their respective receptors in the human cerebrovascular bed and trigeminovascular system. In the current study, the expression of mRNA for ADM and the two cloned human CGRP1 receptors (identified here as A-CGRP1 receptors [Aiyar et al., 1996] and K-CGRP1 receptors) [Kapas and Clark, 1995] were evaluated in human brain vessels and trigeminal ganglia. Further, the ability of CGRP and ADM to activate adenylate cyclase in cerebromicrovascular and astroglial cell cultures was determined, and the receptors involved were characterized pharmacologically. Isolated human pial vessels, intracortical microvessels, and capillaries, as well as cultures of brain endothelial (EC), smooth muscle (SMC), and astroglial (AST) cells, all expressed mRNA for the two cloned CGRP1 receptors; however, message for the K-CGRP1 receptor was barely detectable in microvascular tissues and cells. In contrast, only isolated capillaries and cultured AST exhibited message for the ADM receptor. In human trigeminal ganglia, mRNA for ADM and the two CGRP1 receptors was systematically present. The CGRP dose-dependently increased (up to 50-fold) cAMP formation in cell cultures, an effect significantly blocked by 0.1 to 10 micromol/L of the CGRP1 receptor antagonist CGRP8-37. The ADM receptor agonist, ADM13-52 (1 micromol/L), similarly increased cAMP production in all cell types, and this response was virtually abolished by 1 micromol/L CGRP8-37. Low concentrations (1 to 10 micromol/L) of the ADM receptor antagonist ADM22-52 blocked the ADM13-52-induced cAMP formation in AST (26% at 10 micromol/L, P < 0.05), whereas they potentiated this response in brain EC and SMC (40% and 100%, P < 0.001, respectively). Even at a higher dose (50 micromol/L), ADM22-52 inhibited the ADM13-52 effect in vascular cells (45%) much less effectively than in AST (95%). These results indicate that both CGRP and ADM can affect human brain vessels through a CGRP1 receptor, and they further suggest the presence of functional ADM receptors in human astroglial cells." [Abstract]

Freund TF, Hajos N, Acsady L, Gorcs TJ, Katona I.
Mossy cells of the rat dentate gyrus are immunoreactive for calcitonin gene-related peptide (CGRP).
Eur J Neurosci 1997 Sep;9(9):1815-30
"The neuropeptide calcitonin gene-related peptide (CGRP) was localized in the hippocampus and dentate gyrus of the rat by immunocytochemistry at the light and electron microscopic levels. Without colchicine treatment only faint neuropil labelling was found in the inner molecular layer of the dentate gyrus. Following colchicine treatment, a large number of neurons with numerous complex spines along the proximal dendrites were visualized in the hilus of the dentate gyrus, particularly in the ventral areas, and, in addition, staining of the inner molecular layer became stronger. Several CA3c pyramidal cells located adjacent to the hilar region in the ventral hippocampus also appeared to be faintly positive, although in most cases only their axon initial segments were labelled. Outside this region, the subicular end of the CA1 subfield contained occasional CGRP-positive non-pyramidal cells. The hilar CGRP-positive neurons were negative for parvalbumin, calretinin, cholecystokinin and somatostatin, whereas most of them were immunoreactive for GluR2/3 (the AMPA-type glutamate receptor known to be expressed largely by principal cells). Correlated electron microscopy showed that the spines along the proximal dendritic shafts indeed correspond to thorny excrescences engulfed by large complex mossy terminals forming asymmetrical synapses. Pre-embedding immunogold staining demonstrated that CGRP immunoreactivity in the inner molecular layer was confined to axon terminals that form asymmetrical synapses, and the labelling was associated with large dense-core vesicles. The present data provide direct evidence that CGRP is present in mossy cells of the dentate gyrus and to a lesser degree in CA3c pyramidal cells of the ventral hippocampus. These CGRP-containing principal cells terminate largely in the inner molecular layer of the dentate gyrus, and may release the neuropeptide in conjunction with their 'classical' neurotransmitter, glutamate." [Abstract]

Dumont Y, Fournier A, St-Pierre S, Quirion R.
A potent and selective CGRP2 agonist, [Cys(Et)2,7]hCGRP alpha: comparison in prototypical CGRP1 and CGRP2 in vitro bioassays.
Can J Physiol Pharmacol 1997 Jun;75(6):671-6
"Taken together, these results suggest that [Cys(Et)2,7]hCGRP alpha is a new potent analogue that could prove valuable in addressing the functional relevance of the CGRP2 receptor class." [Abstract]

Mathe AA, Gruber S, Jimenez PA, Theodorsson E, Stenfors C.
Effects of electroconvulsive stimuli and MK-801 on neuropeptide Y, neurokinin A, and calcitonin gene-related peptide in rat brain.
Neurochem Res 1997 May;22(5):629-36
"Rats were pretreated with 0.9% NaCl, or 0.1 or 1.0 mg/kg MK-801, an anticonvulsant and a psychotomimetic drug, and 60 minutes later given ECS or sham ECS. After six sessions the animals were sacrificed and neuropeptide Y (NPY-), neurokinin A (NKA-), and calcitonin gene-related peptide (CGRP-) like immunoreactivity (-LI) measured with radioimmunoassays. ECS increased NPY-LI in frontal cortex, striatum, occipital cortex and hippocampus, and NKA-LI in occipital cortex and hippocampus. MK-801 increased CGRP in a dose-response manner in frontal cortex, and NKA-LI in occipital cortex. Although the higher MK-801 dose reduced seizure duration by 50%, the ECS induced NPY-LI increase in striatum, occipital cortex and hippocampus, and NKA-LI in occipital cortex was not diminished. In contrast, there was a parallel decrease in seizures and NPY-LI and NKA-LI changes in frontal cortex and hippocampus, respectively. Investigation of neuropeptides in brain may contribute to understanding of the mechanisms of action of antidepressive and antipsychotic treatments and of psychotomimetic drugs." [Abstract]

Ludwig R, Feindt J, Lucius R, Petersen A, Mentlein R.
Metabolism of neuropeptide Y and calcitonin gene-related peptide by cultivated neurons and glial cells.
Brain Res Mol Brain Res 1996 Apr;37(1-2):181-91
"Neuropeptide Y and calcitonin gene-related peptide are abundant neuropeptides in the mammalian central and peripheral nervous systems. Their enzymatic degradation by cultivated neurons, astrocytes, and microglia, as well as by purified urokinase-type plasminogen activator, plasmin, thrombin, and trypsin, was investigated in an in vitro approach to elucidate the role of matrix-degrading serine proteinases for inactivation of neuropeptides, especially those of higher amino acid chain length, in the brain. Astrocytes were almost unable to catabolize the peptides. Cultivated neurons and microglia digested neuropeptide Y through cleavage after Arg19, Arg25, Arg33, and Arg35, calcitonin gene-related peptide was cleaved after Arg11 and Arg18. The same cleavage pattern was observed, when neuropeptide Y and calcitonin gene-related peptide were degraded by purified urokinase-type plasminogen activator, plasmin, thrombin, and trypsin. For further characterization of the neuropeptide-degrading serine proteinase activities from cell cultures, urokinase-type plasminogen activator was identified on microglia by immunostaining, whereas tissue-type plasminogen activator mRNA occurred in neurons and astrocytes, but not in microglia. The data are consistent with the possibility that the neuropeptide-degrading serine proteinase activity on neurons and microglia is due to a mixture of plasmin and plasminogen activator activities." [Abstract]

Bouchard P, Monnet F, Bergeron R, Roman F, Junien JL, de Montigny C, Debonnel G, Quirion R.
In vivo modulation of sigma receptor sites by calcitonin gene-related peptide in the mouse and rat hippocampal formation: radioligand binding and electrophysiological studies.
Eur J Neurosci 1995 Sep 1;7(9):1952-62
"Possible interactions between sigma (sigma) receptor sites and calcitonin gene-related peptides (CGRP) were investigated using receptor subtype-related analogues and fragment in in vivo [3H](+)SKF 10 047/sigma binding in the hippocampus, and electrophysiological recording of the N-methyl-D-aspartate (NMDA)-induced activation of CA3 pyramidal neurons, two well-established sigma assays. In both paradigms, CGRP and the agonist [Cys(ACM)2,7]hCGRPalpha modulated sigma systems. In vivo binding experiments demonstrated that CGRP and [Cys(ACM)2,7]hCGRPalpha inhibited 25-40% of specific [3H](+)SKF 10 047 labelling in the mouse hippocampal formation while the purported antagonist hCGRP8-37 was inactive. The specificity of this modulation was demonstrated further by the lack of effect of other vasoactive peptides, including the atrial natriuretic peptide, substance P, and its N-terminal fragment, substance P1-7. In the CA3 subfield of the rat dorsal hippocampus, hCGRP alpha decreased (up to 61%) the NMDA-induced activation of the pyramidal neurons. Conversely, the linear analogue [Cys(ACM)2,7]hCGRP alpha enhanced (by 85%) the NMDA-induced activation of CA3 pyramidal neurons, while the antagonistic fragment hCGRP8-37 had no effect. Haloperidol, a high-affinity sigma receptor ligand, inhibited by 90% the in vivo [3H](+)SKF 10 047 labelling, and prevented the modulation of the NMDA-induced activation by hCGRP alpha and [Cys(ACM)2,7]hCGRP alpha. It thus appears that CGRP can modulate sigma-related systems in the hippocampal formation." [Abstract]

Reddington M, Priller J, Treichel J, Haas C, Kreutzberg GW.
Astrocytes and microglia as potential targets for calcitonin gene related peptide in the central nervous system.
Can J Physiol Pharmacol 1995 Jul;73(7):1047-9
"Injury of peripheral motoneurons leads to the activation of astrocytes and microglia in the vicinity of the damaged neurons in the central nervous system. It has been proposed that neuropeptides such as the calcitonin gene related peptide (CGRP), which show an increased expression in motoneurons following axotomy, play a role as signalling molecules mediating the interactions between the damaged neurons and surrounding glial cells. Evidence supporting this hypothesis is provided by in vitro investigations of the actions of neuropeptides on glial cells. CGRP induces activation of both astrocytes and microglia at the transcriptional level, as seen by the stimulation of mRNA for the immediate early gene, c-fos, in these cells in culture. In addition to its stimulation of immediate early gene expression, treatment of astrocyte cultures with CGRP stimulated release of the tissue plasminogen activator and led to the accumulation of mRNAs for tissue plasminogen activator and the plasminogen activator inhibitor 1. These components of the plasminogen activator system, which has been implicated in processes of tissue remodelling, are upregulated in astrocytes in the facial nucleus in vivo after facial nerve axotomy. The data suggest a role for CGRP as a mediator of glial cell activation following motoneuron injury." [Abstract]

Roesser JR, Liittschwager K, Leff SE.
Regulation of tissue-specific splicing of the calcitonin/calcitonin gene-related peptide gene by RNA-binding proteins.
J Biol Chem 1993 Apr 15;268(11):8366-75
"Transcripts of the rat calcitonin/calcitonin gene-related peptide (CGRP) gene are alternatively spliced in a tissue-specific manner resulting in the production of calcitonin mRNA and peptide in thyroid C cells and CGRP mRNA and peptide in neurons. Transfection studies using calcitonin and chimaeric human beta-globin/calcitonin exon minigene constructs showed that the splice acceptor and exon specific to calcitonin mRNA are spliced much less efficiently in CGRP-producing cells (F9 teratocarcinomas) than in cells that preferentially make calcitonin (HeLa cells). In vitro splicing of chimaeric human beta-globin/calcitonin transcripts in HeLa nuclear extracts were inhibited by the addition of nuclear extract from CGRP-favoring cells or tissues such as rat brain. This inhibition was specific as splicing of human beta-globin first intron transcripts was not affected by comparable amounts of rat brain extract. Fractionation of rat brain nuclear extracts allowed the partial purification of two brain-specific polypeptides of apparent molecular mass of 43 and 41 kDa which preferentially bind RNA containing the calcitonin-specific splice acceptor. Since these polypeptides cofractionate with the calcitonin mRNA-specific splicing inhibition activity, we suggest that they may mediate the inhibition of splicing observed in vitro and underlie, in part, the inefficient calcitonin mRNA production observed in CGRP-favoring cells in vivo." [Abstract]