Calcitonin gene-related peptide and its binding sites in the human central nervous system and pituitary.

Abstract

Binding sites for synthetic human 1251-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 (<0.04 fmol/mg). Autoradiography showed distinct 1251-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 CGRPlike 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.The existence of rat and human calcitonin gene-related peptide (CGRP) has been predicted by analysis of the nucleotide sequence of the calcitonin gene (1, 2). CGRP is a unique 37 amino acid peptide that shares greater structural homology with salmon calcitonin-(1-32) than with rat and human calcitonin-(1-32) (1-3). Expression of CGRP was shown immunohistochemically and by specific RIA in combination with gelpermeation chromatography and HPLC in the nervous system and in the pituitary and thyroid glands (4-6). The amino acid sequence was derived from human medullary carcinoma of the thyroid (7).Here we report distinct regional distribution of CGRP and calcitonin (CT) binding sites in the human central nervous system. The presence of endogenous CGRP-like components in the nervous system, pituitary, and thyroid was revealed by a radioreceptorassay (RRA) using human cerebellar membranes, by RIA, and by immunohistochemistry. MATERIALS AND METHODSTissues and Peptides. Tissue obtained at autopsy within 20 hr postmortem was frozen on dry ice and stored at -80°C for a maximum of 3 wk. Patients with malignant tumors, chronic renal insufficiency, or metabolic bone disease were excluded from the study.Synthetic salmon CT-( Receptor Binding Studies. Membranes were prepared and incubated as described (8, 9) with 17,000 dpm (1 dpm = 16.7 mBq) of human 125I-labeled CGRP (125I-CGRP) Ci/mmol) or salmon 125I-labeled CT (125I-CT) Ci/mmol). Specific binding was defined as total binding minus binding in the presence of 0.7 ,uM unlabeled human CGRP or salmon CT, respectively. A RRA for CGRP was developed using membranes fro...

Calcitonin gene‐related peptide is localised to human airway nerves and potently constricts human airway smooth muscle

“…This suggests that in airway smooth muscle CGRP may act by activation of a specific receptor. A similar conclusion has been reached in studies on pancreatic acinar cells (Zhou et al, 1985), and recently specific receptors for CGRP have been characterized in brain homogenates by direct binding with '25I-labelled CGRP (Tschopp et al, 1985).…”

Isolation and characterisation of a human calcitonin‐gene‐related‐peptide receptor

“…In keeping with previous work which describes human calcitonin and CGRP receptor tissue distribution, and receptor binding studies in membrane preparations from a number of species including man [18,22,24,251, the alternative gene by sucrose gradient centrifugation in the presence of Triton X-100, whilst cross-linking analyses of the solubilised partially purified glycoprotein preparation and the affinity purified receptor confirm the presence of a number of proteins which may be cross-linked using DSS to '251-a-CGRP, ranging in M I from 62000 to 68000. Whether this represents the contribution of a number of subunits to a single binding site, or specific CGRP binding to each subunit, remains to be established, though evidence points to the former.…”

“…Analysis of ' "I-CGRP binding activity to crude membrane, solubilised membrane, or purified receptor preparations were performed essentially as described by Tschopp et al [24]. Analyses were performed at 4°C for 3 h in a final volume of 300 pl.…”

Targeting CGRP: A New Era for Migraine Treatment

“…CGRP may work at the intersection between the peripheral and central components of migraine [36]. In the periphery, CGRP is abundantly present in dorsal horn cells co-stored with substance P in primary sensory ganglia, and with acetylcholine in motor neurons [37,38]. In the CNS, CGRP is involved in modulating pain transmission [39].…”