Immunohistochemical Localization of Calcitonin Receptor–Like Receptor and Receptor Activity–Modifying Proteins in the Human Cerebral Vasculature

Abstract

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.

CGRP Receptor Antagonism and Migraine

“…In intracranial blood vessels, CGRP receptor components were found in the smooth muscle cells. 74 In addition, we have observed both CLR and RAMP1 in human trigeminal ganglion cells. Although CGRP can be seen in thin sensory fibers in the layers I/II of the trigeminal nucleus caudalis region, it has been difficult to obtain positive staining of the CGRP receptor components in this region (L. Edvinsson, unpublished data).…”

“…75 The basic mechanisms of vascular headaches involve the presence of CGRP receptor components in cerebral and middle meningeal arteries. 74 Thus, human middle cerebral and middle meningeal arteries and brain microvessels express mRNA for CLR, RAMP1-3, and RCP. Cultured smooth muscle cells and brain microvascular endothelial cells express mRNA for all components except RAMP3.…”

“…Cultured smooth muscle cells and brain microvascular endothelial cells express mRNA for all components except RAMP3. 74 The mRNA for the entire CGRP receptor is expressed on human intracranial arteries. Functional CGRP receptors are localized on the vascular smooth muscle cells of the cranial arteries in particular, because the responses of cerebral veins to CGRP are very weak.…”

Current and prospective pharmacological targets in relation to antimigraine action

“…On the basis of pharmacological criteria, it is known that CGRP may act mainly on CGRP 1 and CGRP 2 receptors (Arulmani et al 2004), with h-αCGRP 8-37 being a 10-fold more potent antagonist at CGRP 1 receptors than at CGRP 2 receptors (Quirion et al 1992 Gupta et al 2006a;Jansen-Olesen et al 2003;Oliver et al 2002). The results from our laboratory also advocate the presence of CGRP 1 receptors in human meningeal (Gupta et al 2006a) and coronary (Gupta et al 2006b) arteries, while in human distal coronary artery, there seems to be an additional population of CGRP receptors not complying with the current classification of CGRP 1 or CGRP 2 receptors (Gupta et al 2006b).…”

Expression of disrupted in schizophrenia 1 (DISC1) protein in the adult and developing mouse brain indicates its role in neurodevelopment

“…1 Specific immune reactivity of antisera was ascertained using dot blot analysis as described previously. 1,27 In order to provide further controls for D27 antibody and to demonstrate its specificity, preabsorbtion with a peptide was performed. D27 antibody was preincubated for 4 h with a 10 Â excess of immunizing peptide before use.…”