INCREASE IN GLUCOSE-STIMULATED INSULIN RELEASE AND INSULIN-BIOSYNTHESIS IN ISOLATED PANCREATIC-ISLETS FROM D-GALACTOSAMINE-TREATED RATS

Insulin secretion in response to glucose, glucose-stimulated insulin biosynthesis and insulin content was studied in pancreatic islets freshly isolated from male Wistar rats (150-200 g) with galactosamine-induced hepatitis. Animals were sacrificed by decapitation 3, 6, 12 and 24 hours after a single intraperitoneal injection of 500 mg/kg of galactosamine. Isolated islets prepared by collagenase method were perifused in Swim's medium with 20 mM glucose at 37°C up to 30 minutes. Samples were taken at 2-10 min intervals for insulin assay. Insulin biosynthesis was assessed by the incorporation of [3H]-leucine into immunoprecipitable products (insulin and proinsulin) in pancreatic islets after 120 min incubation with 20 mM glucose. Glucose-stimulated insulin secretion was significantly increased at 6, 12 and 24 hours following the administration of galactosamine compared to control. The rate of insulin biosynthesis was stimulated to 170, 138 and 185% of control level 3, 6 and 12 hours after galactosamine-treatment, respectively. Significant increase in insulin content of islets was found 24 hours after galactosamine treatment, following the increased insulin biosynthesis. The present results indicate that pancreatic B cell function is activated in early stage of acute liver injury.