EFFECTS OF GLUCAGON-INFUSION, ALONE OR IN COMBINATION WITH SOMATOSTATIN, ON PLASMA GROWTH-HORMONE AND METABOLITE LEVELS IN YOUNG FEMALE TURKEYS UNDER DIFFERENT FEEDING REGIMENS

The lipolytic effect of glucagon alone or in combination with somatost atin-14 (SRIF-14) was studied in 9- to 11-wk-old female turkeys that e ither consumed feed ad libitum or were deprived of feed (FD) for 20 h. During the infusion of various doses of glucagon (.005 to 1.5 mug glu cagon/min), blood samples were serially collected every 10 min for det ermination of plasma concentrations of growth hormone (GH) and energy- related metabolites [nonesterified fatty acids (NEFA), glucose, and tr iacylglycerol (TG)]. Glucagon infusion resulted in decreases (P <.05) in plasma GH in both groups of turkeys. During glucagon infusion, dose -dependent increases in both glucose and NEFA occurred, with greater r elative increases in the ad libitum turkeys. In contrast, plasma TG wa s decreased by glucagon infusion in the ad libitum turkeys but unchang ed in the FD turkeys. The effect of simultaneous infusion of SRIF-14 a nd glucagon on GH and NEFA concentrations varied depending on the prev ious hormonal treatment. Plasma glucose was not affected by SRIF-14 in either group of turkeys. The present studies show that: 1) glucagon i s an important agent for directing carbohydrate and lipid metabolism i n growing female turkeys; 2) SRIF-14 has little effect on carbohydrate metabolism, but does affect lipolysis in a complex manner with glucag on; and 3) in vivo, glucagon depresses plasma GH.