Effect of Ganoderma lucidum hydroalcoholic extract on insulin release in rat-isolated pancreatic islets

Ganoderma Lucidum (G. Lucidum) has been suggested to increase serum insulin level. This study was undertaken to investigate its direct effect on the islets of Langerhans. Male albino Wistar rats were anesthetized and the islets were isolated after digestion of the pancreas with collagenase. The islets were incubated for 60 min in Krebs bicarbonate buffer containing 3 or 10 mM glucose in the presence of hydroalcoholic extract of G. Lucidum (1 mg/ml), 3-isobutyl-1-methylxanthine (IBMX, 100 μM) or vehicle. Exposure of islets to the extract increased insulin secretion at basal (3 mM) glucose concentration. Increase of glucose concentration to 10 mM resulted in a significant increase in the rate of insulin secretion. While the IBMX could augment insulin release evoked by 10 mM glucose, the extract failed to modify it. Our results demonstrate that G. lucidum acts directly on the Langerhans islets to increase basal insulin release.