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Molecular Characteristics and Peptide Specificity of Vasoactive Intestinal Peptide Receptors from Rat Cerebral Cortex
Author(s) -
Couvineau Alain,
Gammeltoft Steen,
Laburthe Marc
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb00780.x
Subject(s) - vasoactive intestinal peptide , secretin , secretin family , receptor , cholecystokinin , chemistry , neuropeptide , endocrinology , peptide , medicine , somatostatin , gastrointestinal hormone , cerebral cortex , peptide hormone , biochemistry , biology , pancreas
Vasoactive intestinal peptide (VIP) receptors have been identified in CNS by their chemical specificity and molecular size. Using synaptosomes isolated from rat cerebral cortex, it was shown that central VIP receptors discriminated among natural and synthetic VIP‐related peptides, because half‐maximal inhibition of [ 125 I]VIP binding to synaptosomes was obtained for 0.6 n M VIP, 9 n M peptide histidine isoleucineamide (PHI), 50 n M VIP 2–28, 70 n M secretin, 100 n M rat growth hormone‐releasing factor (GRF), and 350 n M human GRF. Other peptides of the VIP family, such as glucagon and gastric inhibitory polypeptide, did not interact with cortical VIP receptors. The molecular components of VIP receptors in rat cerebral cortex were identified after [ 125 I]VIP cross‐linking to synaptosomes using the cross‐linker dithiobis(succinimidyl propionate). Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of synaptosomal proteins revealed two major [ 125 I]VIP‐pro‐tein complexes of M r 49,000 and 18,000. The labeling of the M r 49 ,000 component was specific, because it was abolished by native VIP, whereas the labeling of the M r 18,000 component was not. Natural VIP agonists reduced the labeling of the M r 49 ,000 component with the following order of potency: VIP > PHI > secretin ∼ rat GRF. In contrast, glucagon and octapeptide of cholecystokinin were without effect, a result indicating its peptide specificity. Densitometric scanning of autoradiographs showed that the labeling of the M r 49,000 component was inhibited by low VIP concentrations between 10 − ‐ 10 and 10 − ‐ 6 M (IC 50 = 0.8 n M ), a result indicating the component's high affinity for VIP. Labeling was also reduced by GTP in the concentration range between 10 − ‐ 7 and 10 − ‐ 3 M (ED 50 = 5 μ M ). Assuming that one molecule of [ 125 I]VIP is bound per molecule of synaptosomal protein, a major protein of M r 46,000 was identified as a component of the VIP receptor in rat cerebral cortex.