EFFECTS OF SOMATOSTATIN ON PLASMA GROWTH-HORMONE AND METABOLITE CONCENTRATIONS IN FED AND FEED-DEPRIVED YOUNG FEMALE TURKEYS

The sensitivity and magnitude of response to somatostatin-14 (SRIF-14) infusion in terms of changes in plasma concentrations of growth hormo ne (GH) and energy-related metabolites [nonesterified fatty acids (NEF A), glucose, and triacylglycerides (TG)] were determined in 9- to 11-w k-old fed or feed-deprived (FD; 20 h) female turkeys. The turkeys were sequentially infused with increasing doses of SRIF-14 (.0015 to 1.5 m ug/min) concurrent with serial collection of blood samples (every 10 m in). Plasma GH and NEFA concentrations were lower in fed than in FD bi rds. In fed birds only NEFA was minimally altered by SRIF-14 infusion. In FD birds, GH was decreased, but only at the highest dose of SRIF-1 4 (1.5 mug/min), whereas NEFA was decreased in a dose-dependent manner from .05 to 1.5 mug/min. Very rapid postinfusion rebounds of plasma G H and NEFA were observed in FD birds. Plasma glucose was not influence d by SRIF-14 in either fed or FD birds. Concentrations of plasma TG we re depressed slightly by SRIF-14 in FD but not in fed birds. The prese nt studies indicate that 1) FD birds are more sensitive to SRIF-14 inf usion than are fed birds; 2) in FD birds, inhibition of lipolysis (ind icated by plasma NEFA) is sensitive to lower dosages of SRIF-14 infusi on than is inhibition of GH; and 3) SRIF-14 has little if any effect o n TG and glucose metabolism.