Calcitonin gene-related peptide antagonism for acute treatment of migraine: a meta-analysis

Purpose: Calcitonin gene-related peptide (CGRP) is an effector of acute migraine attack. And the CGRP antagonisms have shown some early promise in the treatment of migraine. Here, we performed a meta-analysis to evaluate the efficacy of CGRP antagonisms in treating acute migraine attack. Methods: Pubmed, Cochrane Library, Web of Science and OvidSP were systematically searched up to 9 April 2015 for randomized controlled trials (RCTs) which is dealing with the efficacy of CGRP antagonisms in treating acute migraine attack. The bias and quality of RCTs were assessed with Cochrane collaboration's tool for assessing risk of bias. Reviewer manager 5.2 was utilized for data analysis. Results: Totally 13 publications matched the inclusion criteria, including 10 independent RCTs and 6803 patients. Pooled analysis indicated that CGRP antagonisms had better outcomes in number of patients with pain free at 2h, 2-24h sustained pain free, phonophobia free at 2h, patients with photophobia free at 2h and nausea free at 2h post-dose, as compared with placebo. But CGRP antagonisms were no superior than 5-HT agonists in the indices above mentioned. Conclusions: CGRP antagonisms may be an effective and promising treatment for acute migraine attack.     

No increase of calcitonin gene-related peptide in jugular blood during migraine

Increased calcitonin gene-related peptide (CGRP) in external jugular venous blood during migraine attack is one of the most cited findings in the headache literature. The finding has not been convincingly reproduced and is based on comparison with historic control subjects. The validity of this finding is important for the understanding of migraine. We therefore investigated the issue using an intrapatient comparison design and two different CGRP assays. We sampled blood from the external jugular and cubital vein during, as well as outside of, an attack of migraine without aura. We succeeded in 17 patients, whereas only cubital fossa blood could be sampled in an additional 4 patients. CGRP was measured with the same assay as most previous studies (assay I) and furthermore with a more sensitive and validated assay (assay II). For assay I, mean CGRP concentration in external jugular venous blood during attack was 17.18 pmol/L compared with 15.88 pmol/L outside of attack. Mean difference was 1.81 pmol/L (95% confidence interval [CI]: -2.88, 6.41; p = 0.44). In peripheral blood during attack, CGRP was 16.86 pmol/L compared with 17.57 pmol/L outside of attack. Mean difference was -0.79 pmol/L (95% CI: -4.64, 3.06; p = 0.69). For assay II, external jugular venous blood concentration of CGRP during attack was 32.59 pmol/L compared with 30.59 pmol/L outside of attack; mean difference was 2.00 pmol/L (standard error, 2.39; 95% CI: -3.07, 7.07; p = 0.416). In peripheral blood during attack, CGRP was 33.37 pmol/L compared with 31.84 pmol/L outside of attack; mean difference was 1.53 pmol/L (standard error, 1.90; 95% CI: -2.46, 5.51; p = 0.431). Thus, no difference between CGRP level in external jugular or cubital fossa blood during and outside of attack was found. No difference was found between external jugular and peripheral venous blood. Thus, previous findings of increased CGRP level in external jugular or cubital fossa venous blood could not be confirmed. Our finding strongly suggests that CGRP is not increased in jugular venous blood during migraine without aura. CGRP cannot be used as a biomarker to validate human or animal models of migraine.     

Placebo and nocebo phenomena in anti- CGRP monoclonal antibody trials for migraine prevention: a meta-analysis

Journal of Neurology - High placebo and low nocebo phenomena mirror high positive expectations for a novel treatment, among other reasons. In a meta-analysis aimed to identify placebo and nocebo...     

Calcitonin and calcitonin gene-related peptide enhance calcium-dependent potentials

Recent data suggests that calcitonin (CT) and/or calcitonin gene-related peptide (CGRP) may be potential transmitters or modulators in the nervous system. The present study analyzed the effect of CT and CGRP on the neuronal membranes of cat parasympathetic ganglia of the urinary bladder. The related peptides prolonged the duration of the afterhyperpolarization of the action potential but had no effect on resting potential or input resistance. CT and CGRP enhanced the duration of a calcium spike recorded in the presence of agents blocking Na and K channels while under similar conditions forskolin, an activator of adenylate cyclase, did not affect the calcium spike. These data suggest that the neural mechanism of action of CT and CGRP is to prolong a calcium conductance and that these effects are not mediated through cyclic AMP.     

Localization of calcitonin gene-related peptide and its receptors in a striated muscle

The distribution of calcitonin gene-related peptide (CGRP) and its binding sites in the bulbocavernosus, a striated muscle, are reported. We used immunohistochemistry and [125I]CGRP autoradiography. The pattern of [125I]CGRP binding was restricted to a discrete band that coincides with the distribution of end-plates in this muscle as determined by CGRP immunohistochemistry and acetylcholinesterase staining. CGRP has been shown to increase the level of acetylcholine receptor (AChR) alpha-subunit mRNA. The role of CGRP as the endogenous factor by which motoneurons regulate the expression of junctional AChR is discussed.     

The effect of melatonin on gene expression of calcitonin gene-related peptide and some proinflammatory mediators in patients with pure menstrual migraine

The neuropeptide calcitonin gene-related peptide (CGRP), a potent vasoactive and a marker of trigeminal inflammation, has been considered as an important mediator in various types of migraine such as pure menstrual migraine. Earlier studies have shown that CGRP can modulate the synthesis and release of other inflammatory factor including nitric oxide (NO) and interleukin-1beta (IL-1β) from trigeminal ganglion glial cells. Exogenous melatonin protects the tissues from inflammatory damages. The goal of this study was to determine the anti-inflammatory effects of melatonin on the CGRP expression, inducible nitric oxide synthase (iNOS) activity, NO, and IL-1β release in cultured peripheral blood mononuclear cells (PBMCs) from pure menstrual migraine patients and healthy subjects. This study was performed on 12 pure menstrual migraine patients and 12 age-and sex-matched healthy subjects. PBMCs were isolated and treated with melatonin for 12 h at pharmacological dose. Gene expression was evaluated by real-time PCR. CGRP and IL-1β proteins in culture supernatant were determined by ELISA method. iNOS activity in PBMCs was determined by colorimetric assays. Total nitrite as an indicator of NO concentrations in the culture supernatants was measured using Griess method. We found that melatonin treatment significantly decreases mRNA expression of CGRP release, NO production, and iNOS activity in the patient groups. Taken together, it appears that melatonin reduces inflammation through decreasing CGRP level and iNOS activity in the patients with migraine; however, further studies are needed in this regard.     

Distinct binding sites for calcitonin gene-related peptide and salmon calcitonin in rat central nervous system

Calcitonin gene-related peptide (CGRP) binding sites have been identified in homogenates from the rat brain and spinal cord. Autoradiography with [¹²⁵I]rat CGRP (rCGRP) revealed high grain density over the lateral hypothalamus, vestibular nuclei, colliculi, medial geniculate body, corpus mamillare and the molecular layer of the cerebellum which lacked binding sites for [¹²⁵I]salmon calcitonin (sCT). In contrast, no rCGRP labeling was seen over the anterior and dorsomedial hypothalamus which showed high sCT binding. The different regional distribution of rCGRP and sCT binding sites indicates that the structurally related peptides interact with separate receptors. The overlap between the localization of CGRP binding sites and endogenous CGRP in many regions of the central nervous system suggests that CGRP exerts unique physiological functions in the central nervous system.     

Production and secretion of calcitonin gene-related peptide from human lymphocytes

Programmed cell death (apoptosis) is critical for the normal development and homeostasis of the immune system. There is increasing evidence that dysregulations of apoptotic pathways are associated with autoimmune disease, including multiple sclerosis (MS). Cellular commitment to apoptosis is partly regulated by the Bcl-2 family proteins, which includes the death antagonists Bcl-2 and Bcl-X(L), and death agonists Bax and Bad. Since the role of these proteins in the pathogenesis of MS is currently unknown, we analyzed their expression profile in peripheral and intrathecal lymphocytes from MS patients and appropriate controls. We observed a significant reduction in the expression ratios of pro-apoptotic to anti-apoptotic Bcl-2 members in both peripheral and intrathecal lymphocytes from MS patients when compared to corresponding ratios in patients with inflammatory or noninflammatory neurologic controls, or healthy individuals. The relative coexpression ratios of these pro- and anti-apoptotic Bcl-2 family proteins in MS were more significant than the expression of individual members. The low cellular expression ratios of pro-apoptotic proteins in MS were confirmed in vitro activated T lymphocytes. Cellular expression of Bcl-2, Bcl-X(L), Bax or Bad in MS patients was independent of the expression of other apoptotic regulatory molecules, such as Fas receptor protein or FLIP. Our findings suggest that the abnormal expression patterns of Bcl-2 family proteins in MS may promote apoptotic resistance of potentially pathogenic, autoreactive lymphocytes, and may allow for continuing cellular proliferation and tissue destruction within the central nervous system.     

Hypoprolactinemic effect of calcitonin gene-related peptide in the rat

The effect of calcitonin gene-related peptide (CGRP) on prolactin (PRL) secretion was studied in female rats. Prepubertal female rats were submitted to the stressful stimuli of injection, blood puncture and thermal stress. Lactating rats were exposed to suckling stimulus. The effects of CGRP on PRL release were compared to those of calcitonin (CT). CGRP i.p. or s.c. prevents the increase in circulating PRL induced by stress. This effect was observed two hrs and even 24 hrs after CGRP administration. It was elicited at all doses tested, 2.5, 1.25 and 0.6 micrograms per animal. The time course of the actions of CGRP and CT are different. It is proposed that CGRP and CT act on different receptors.     

降钙素基因相关肽神经生长因子与失神经支配兔骨折愈合

背景：骨折不愈合严重影响患者生活质量,神经生长因子用于骨不连的防治是重建外科领域研究的重点和方向。 目的：观察神经生长因子降钙素基因相关肽对失神经支配兔骨折愈合的影响。 方法：构建大白兔失神经支配腓骨骨折模型后,实验组骨折端局部注射降钙素基因相关肽10 μg,每2 d一次;对照组骨折端局部注射等量生理盐水。术后2,4,6周分别测定静脉血中肾上腺素和去甲肾上腺素的水平,并进行生物力学和组织学分析。 结果与结论：术后两组血清肾上腺素和去甲肾上腺素水平均有显著增高,在术后第4周达到最高峰,比术前高出1倍以上,第6周时出现下降,但仍然显著高于术前;术后2,4,6周,实验组肾上腺素和去甲肾上腺素血清水平较对照组显著增高,差异具有显著性意义(P < 0.05~0.01)。在三点弯曲实验中,实验组骨痂的抗弯强度明显高于对照组(P < 0.05~0.001);术后第6周时苏木精-伊红染色可见实验组骨痂中的透明软骨细胞已被成骨细胞替代,对照组骨痂中的软骨细胞仍没有完全成骨细胞化。提示神经生长因子降钙素基因相关肽对失神经支配兔骨折愈合具有明显的促进作用。 关键词：神经生长因子;降钙素基因相关肽;骨折愈合;生物力学;生物化学     

Molecular cloning and characterization of mouse calcitonin gene-related peptide receptor

The calcitonin gene-related peptide (CGRP) plays important roles as a neurotransmitter/neuromodulator in the central nervous system, and as a potent vasodilator when secreted from peripheral, perivascular nerves through its specific receptors. In this study, we cloned mouse cDNA counterparts of the human CGRP receptor composed of calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 1 (RAMP1) and examined the signal transduction mechanism through the CGRP receptor. Mouse CRLR (mCRLR) is a 462-amino acid G protein-coupled heptahelical receptor, and mouse RAMP1 (mRAMP1) is a 148-amino acid single membrane-spanning protein with a short cytoplasmic portion. Specific binding of (125)I-CGRP was detected only when both mCRLR and mRAMP1 cDNAs were cotransfected to COS-7 cells, and the Kd value of the receptor was 2.2 x 10(-10) M. CGRP induced a marked elevation of the intracellular cAMP levels in COS-7 cells cotransfected with mCRLR and mRAMP1. CGRP signaling through the mCRLR/mRAMP1 receptor complex was found to increase the promoter activities of cyclic AMP responsive element and serum responsive element in the co-transfected HeLa cells. These results indicate that mCRLR and mRAMP1 constitute a functional mouse CGRP receptor for the transduction of CGRP signaling by PKA and extracellular signal-regulated kinase signal transduction pathways.     

The myotropic and plasma-calcium modulating effects of calcitonin gene-related peptide (CGRP)

Human and rat calcitonin gene-related peptides cause a dose-related contraction of guinea pig ileum, which is antagonised by an anti-histamine, mepyramine, and an anticholinergic compound, hyoscine. Both peptides also cause a positive inotropic and a positive chronotropic effect in the rat isolated auricle and these responses are antagonised by propranolol, a B adrenoceptor blocker. Further, the peptides lower plasma calcium levels in both rats and rabbits in a dose-related manner resembling calcitonin; in the rabbit, but not in the rat, the initial calcium lowering effect is succeeded by hypercalcaemia at higher doses, while in the chick, only the parathyroid hormone-like calcium-raising effect is seen.     

Regulation of calcitonin gene-related peptide secretion by a serotonergic antimigraine drug.

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.     

Binding sites for calcitonin gene-related peptide in distinct areas of rat brain

Calcitonin gene-related peptide (CGRP) binding sites were localized in rat brain and spinal cord by an in vitro labeling light microscopic technique using [125I]rCGRP as radioligand. Specific rCGRP binding with a dissociation constant (Kd) of 0.53 nM to membrane preparations from rat brain cortex was characterized. The presence and the selective distribution of specific high affinity CGRP binding sites in the central nervous system suggest a role for this recently predicted peptide as a neurotransmitter.     

Antinociceptive profile of intracerebroventricular salmon calcitonin and calcitonin gene-related peptide in the mouse formalin test

The effects of intracerebroventricularly administered salmon calcitonin (sCT) and calcitonin gene-related peptide (CGRP) on the behavioural response of the mouse to formalin injections were investigated. Mice lick their hindpaws for 5 min after formalin injections, then stop, and resume intensive licking for another 10 min beginning 20 min after the injections. Both peptides reduced the nociceptive response in the two phases of the test (0-5 and 20-30 min after formalin injection). Antinociceptive A50 values were 3.3 micrograms/mouse and 4.7 micrograms/mouse respectively in the first phase for sCT and CGRP. The effects of sCT and CGRP appeared to be dose-dependent in the first phase. Since in the second phase sCT appeared more effective and CGRP gave a bell-shaped curve, possible differences in the mechanisms of action of the peptides in the two response intervals of the test are suggested.     

Occurrence of calcitonin gene-related peptide in the chicken amacrine cells

The distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity (CGRPI) in the chicken retina was investigated by means of immunohistochemistry. CGRPI was localized in the stratified amacrine cells. The terminal branching pattern of these cells was different between the central and peripheral retinal regions. Flat-mount preparations revealed these CGRPI cells to be evenly distributed in the entire retina with surprisingly rich arborization.