Somatostatin inhibition of thyrotropin-releasing hormone- and growth hormone-releasing factor-induced growth hormone secretion in young and adult anesthetized chickens.
The present communication examines the influence of somatostatin (SRIF14) on basal and thyrotropin-releasing hormone (TRH)- or growth hormone-releasing factor (GRF)-induced GH secretion in young (6 week old) and adult male chickens. Studies were performed in sodium pentobarbitone-anesthetized chickens where basal plasma concentrations of GH are low and both TRH and GRF consistently stimulate GH release. In both young and adult chickens, basal GH secretion was reduced by SRIF14 infusion (3 micrograms/kg/min). Similarly, in adult and young birds, the GH secretory response to a challenge with a GRF bolus (10 micrograms/kg) was inhibited by the concomitant intravenous infusion of SRIF14 (0.3 or 3.0 micrograms/kg/min). In adult chickens, the GH response to TRH (10 micrograms/kg) was suppressed (by 93%) by SRIF14 infusion (3 micrograms/kg/min) and tended to be inhibited (by 29%) by a lower dose of SRIF14 (0.3 micrograms/kg/min). In contrast, in young chicks, GH release following TRH challenge (either 1 or 10 micrograms/kg) was only partially inhibited by SRIF14 infusion (3 micrograms/kg/min). The response to a TRH challenge (10 micrograms/kg) was unaffected by the low dosage of SRIF14 infusion (0.3 micrograms/kg/min). It is concluded that SRIF14 inhibits both GRF- and TRH-stimulated GH release in young and adult chickens.
Scanes
C G
CG
Department of Animal Sciences, Rutgers State University, New Brunswick, New Jersey 08903.
Harvey
S
S
D000375:Aging / Q000502:physiology*; D000818:Animals; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000502:physiology*; D007262:Infusions, Intravenous; D008297:Male; D010424:Pentobarbital; D013004:Somatostatin / Q000494:pharmacology / Q000502:physiology*; D013973:Thyrotropin-Releasing Hormone / Q000502:physiology*
D013004:Somatostatin; D013973:Thyrotropin-Releasing Hormone; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D010424:Pentobarbital