Insulin-induced hypoglycemia stimulates gluconeogenesis from 14C-lactate independently of glucagon and adrenaline releases in rats

Correlation between blood glucose, glucagon and adrenaline levels and gluconeogenesis was studied during the recovery from insulin-induced hypoglycemia in rats. Rats, overnight fasted, were intravenously injected with 40 microCi/kg of [U-14C]-lactate and 1 U/kg of porcine insulin under an anesthesia with pentobarbital sodium. Blood samples were drawn via the peripheral vein at 0, 5, 10 and 20 min. Plasma insulin level was 617 +/- 115 microU/ml at 5 min. Plasma glucose level was significantly decreased at 5 min (2.7 +/- 0.3 mM at 5 min v.s. 4.3 +/- 0.2 mM at 0 min, P < 0.01). Plasma glucagon and adrenaline did not significantly respond at 5 min, and then rised. Specific radioactivity of plasma [1-14C]-glucose was significantly higher at 5 and 10 min in the insulin-injected rat than the saline-injected rat (204 +/- 34 v.s. 130 +/- 14 d.p.m./mumol at 5 min, P < 0.01; 275 +/- 32 v.s. 186 +/- 16 d.p.m./mumol at 10 minm P < 0.01). These results suggest that lowering of blood glucose level stimulates gluconeogenesis independently of the release of counter-regulatory hormones in insulin-induced hypoglycemia.