Influence of regimen and insulinemia on orexigenic effects of GRF1-44 in sheep.
The effects of intracerebroventricular (ICV) and intravenous (IV) administration of human GRF1-44 on feeding behavior were tested in hay- and concentrate-fed non lactating ewes. Administered ICV 5 min prior to hay disposal in 16 hr fasted ewes, GRF1-44 increased the first 3 hr and daily (8 hr) food intake by 25.3 and 24.5% respectively; this corresponded to a higher rate of ingestion during the first 3 hr. Similar effects on feeding behavior were observed after IV administration of a 10-times greater dose of GRF1-44 (1 microgram X kg-1), with daily hay consumption increasing from 1125 +/- 44 g (control) to 1407 +/- 91 g. In contrast, food intake of concentrates was significantly (p less than 0.05) higher only during the first hour of feeding and the daily food intake was unchanged. Both ICV (40 mU X kg-1) and IV (400 mU X kg-1) administrations of insulin did not affect feeding behavior per se, but suppressed the increased food intake of hay induced by IV GRF1-44. It is concluded that the orexigenic effects of GRF1-44 are probably centrally mediated and depend on regimen and digestive status. It is suggested that the insulin response to a meal of concentrates may be responsible for the early blockade of the orexigenic effects of GRF.
D000821:Animal Feed; D000818:Animals; D001066:Appetite / Q000187:drug effects*; D002552:Cerebral Ventricles / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D007328:Insulin / Q000097:blood* / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D012756:Sheep
D007328:Insulin; D010446:Peptide Fragments; D013007:Growth Hormone-Releasing Hormone