Endocrine Abstracts

Diabetes Mellitus is a chronic disease characterised by hyperglycaemia due to peripheral insulin resistance and/or insulin deficiency. This may be due to a decline in viable pancreatic β-cells number or β-cell dysfunction leading to impaired nutrient-induced insulin secretion. The most probable causes of these β-cell effects are exposure to elevated levels of inflammatory cytokines, glucose and free fatty acids. There are many synthetic and herbal drugs available for treatment of diabetes. Gypenosides are saponins extracted from the plant Gynostemma pentaphyllum, used in traditional Chinese medicine as an anti-diabetic and anti-obesity drug. Previous studies in animals showed stimulatory effects of this herbal compound on insulin secretion, although its mechanism of action is not yet fully understood. The present study aims to investigate the cytoprotective and insulin stimulatory effects of Gypenoside using the clonal insulin-secreting BRIN-BD11 cell line. Cells viability was determined by MTT following exposure to gypenoside and various cytotoxic agents for 24–96 h. Gypenoside provided significant cytoprotective effect against palmitate and peroxide-induced cytotoxicity. Gypenoside effects on insulin release under basal and high glucose concentrations were determined over 1 h and measured by ELISA. Gypenoside (100 μg/ml) enhanced insulin secretion by 4.4-fold (P<0.001) at 1.1 mM glucose and 3-fold (P<0.001) at 16.7 mM glucose. This was similar to secretion in the presence of 10 mM L-alanine with increases in insulin secretion of five and three fold at basal and high glucose, respectively. These findings indicate that gypenoside may enhance insulin secretion and protect against oxidative stress and lipotoxicity and may be useful in treatment of type 2 diabetes.