INHIBITORY EFFECT OF VOLATILE FATTY-ACIDS ON GRF-INDUCED GH SECRETIONIN SHEEP

The effect of intravenous infusion of acetate, propionate and butyrate (0, 3, 10. 30 mu mol kg(-1) min(-1) over 40 min) on the secretion of growth hormone (GH), insulin and glucagon in response to growth hormon e-releasing factor (GRF) injection (0.25 mu g/kg, 10 min after the ons et of acid infusion) was determined in six sheep. The intravenous inje ction of GRF caused a marked increase in plasma GH at every dose of ea ch acid. The GH response to GRF was unaffected by an intravenous infus ion of acetate. The basal plasma levels of insulin, glucagon and gluco se were unchanged by acetate infusion. The infusion of propionate mark edly suppressed the GH response to GRF in a dose-dependent manner. Pro pionate produced increases in plasma insulin, glucagon and glucose con centrations. Butyrate infusion also caused a significant attenuation o f GRF-induced GH secretion. Butyrate infusion stimulated the secretion of both insulin and glucagon and caused hyperglycemia. After cessatio n of the infusion of propionate or butyrate plasma GH tended to increa se again. Plasma somatostatin concentrations, which were measured only for the highest dose of butyrate, were unchanged during acid infusion , but increased on discontinuing the infusion. It is concluded that pr opionate and butyrate suppress GH secretion, while stimulating the sec retion of insulin and glucagon in sheep.