Study of the role of novel RFamide neuropeptides

Authors: Fatima Qaiser Fazal Wahab Muhammad Amin Wiqar Rizwan Hashim Jerome Leprince Hubert Vaudry Manuel TenaSempere Muhammad Shahab

Publish Date: 2012/04/22

Volume: 42, Issue: 3, Pages: 658-663

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Abstract

RF amide peptide family with distinctive terminal –Arg–Phe–NH2 signature is evolutionarily conserved from invertebrates to mammals These neuropeptides have been shown to affect diverse functions in invertebrates and vertebrates including influencing pituitary hormone secretion More recently two members of this family 26amino acid and 43amino acid RF amide peptide 26RFa and 43RFa respectively originally isolated from frog have been cloned in rats and humans Actions of these peptides on hormone secretion have not been studied in primates In the present study effect of iv administration of three different doses of human 26RFa and 43RFa on GH secretion was studied in a representative higher primate the rhesus monkey As control against these two peptides normal saline and a scrambled sequence of 26RFa was administered A set of four intact adult male monkeys received the administration in a random order Peripheral blood samples were obtained from the chairrestrained but fully conscious animals for a period of 30 min before and 240 min after the administration at 15min intervals For quantitative measurement of GH concentration a human GH chemiluminescent immunometric assay was used Peripheral administration of 38 and 76 nmol doses of 26RFa significantly P  005 stimulated GH AUC during a 0–120 min period after injection of 26RFa In contrast to 26RFa administration of 43RFa appeared to suppress GH levels during the later stages of the sampling ie from 120 to 240 min period Mean AUC during the period was significantly P  005 reduced by 76 nmol dose of 43RFa while 38 nmol dose of 43RFa also had similar effect but lacked full statistical significance P = 0058 To our knowledge present study reports for the first timespecific stimulatory effect of 26RFa on the GH secretion and a novel inhibitory and delayed effect of 43RFa on the GH secretion in higher primates In conclusion present findings extend evidence for endocrine actions of RF amides in primates and suggest differential effect of these peptides on GH secretion in primates

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