Effects of feeding behavior of rats of a cryptic peptide from the C-terminal end on prepro-growth hormone-releasing factor.
An amidated peptide derived from cleavage of the C-terminal of prepro-GRF [prepro-GRF-(78-107)NH2] and designated CTPG or anorectin was injected ip and into the third ventricle of rats, and food intake and body weight were measured. An acute injection of 0.2, 0.5, or 1.0 microgram CTPG (anorectin; 60, 150, or 300 pmol) into the third ventricle produced a significant dose-related reduction in food intake in the hungry rat during the 12-h dark period. Water intake was suppressed 30% by 1.0 microgram (300 pmol), but the lower doses had no effect. The highest dose (1 microgram or 300 pmol) produced a small rise in glucose concentration 5 min after injection into the third ventricle, which returned to the control value by 15 min. Anorectin increased the sympathetic efferent firing rate 3, 6, and 24 h after a single injection. Intraperitoneal injection of 2.0, 5.0, and 20 micrograms, however, had no significant effect on food or water intake. Chronic infusion into the third ventricle at a rate of 50 ng/h for 7 days produced a persistent reduction in food intake and a steady fall in body weight. The chronically infused rats had a significantly higher level of sympathetic activity, as measured by the firing rate of sympathetic nerves innervating the interscapular brown adipose tissue. These studies raise the possibility that anorectin released during processing of GRF might be involved in the modulation of feeding behavior.
D000818:Animals; D001066:Appetite / Q000187:drug effects*; D001786:Blood Glucose / Q000378:metabolism; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology; D004334:Drug Administration Schedule; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D007328:Insulin / Q000097:blood; D008297:Male; D011498:Protein Precursors / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D001786:Blood Glucose; D007328:Insulin; D011498:Protein Precursors; C047524:pre-pro-growth hormone releasing factor; D013007:Growth Hormone-Releasing Hormone