Intracerebroventricular growth-hormone-releasing peptide-6 stimulates eating without affecting plasma growth hormone responses in rats.
The purpose of this study was to determine the effect of intracerebroventricular (i.c.v.) injections of a synthetic, opioid-related hexapeptide, growth-hormone-releasing peptide-6 (GHRP-6), on stimulation of eating by rats and to correlate this aspect of feeding behavior with the peripheral plasma growth hormone (GH) response to the administered peptide. GHRP-6 dissolved in 5 microL of saline was injected into the lateral ventricles of sated, adult, male, Sprague-Dawley rats in doses from 0 pmol (saline only) to 1000 pmol. For 1 hour after injection, the occurrence of eating was noted, and specimens of arterial blood were collected at 0, 15, 30, and 60 minutes. The plasma was assayed for GH. A nearly linear, statistically significant (p < 0.01) dose-response relationship between the dose of GHRP-6 and the incidence of eating was noted. The mean change from baseline of plasma GH during the 60 minutes after injection was not dose-related (p > 0.2, p > 0.1, and p > 0.1 at 15, 30, and 60 minutes, respectively). We conclude that GHRP-6 given intracerebroventricularly to sated, adult, male, Sprague-Dawley rats stimulates eating and suggest that it does so by some mechanism that is independent of its GH-releasing property.
Locke
W
W
Department of Internal Medicine, Ochsner Clinic, New Orleans, Louisiana 70121, USA.
Kirgis
H D
HD
Bowers
C Y
CY
Abdoh
A A
AA
D000818:Animals; D005247:Feeding Behavior / Q000187:drug effects*; D013006:Growth Hormone / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects; D007276:Injections, Intraventricular; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D009842:Oligopeptides; C041048:growth hormone releasing hexapeptide; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone