The effect of Exendin-4 on apoptosis of islet cells in rats with type I diabetes

Incidence rate of type I diabetes showed an increasing trend. Lifelong exogenous insulin treatment is essential for type I diabetes patients due to insulin-secretion cells dysfunction. This severely affects life quality of patients. Our study is focused to explore the effect of Exendin-4 on apoptosis of type I diabetes rat beta-cells and provide data support for clinical treatment. 120 male Sprague-Dawley rats were randomly assigned into three groups with equal number, including Sham group, type I diabetes group (DM group) and Exendin-4 intervention group (treated group). Type I diabetes rat model was induced with intraperitoneal injection of streptozotocin (STZ, 60 mg/kg). Fasting blood-glucose of rat model was assessed at 72 h after STZ injection to verify type I diabetes rat model, and successful model is defined as fasting blood-glucose > 16.67 mmol/L and maintained four weeks with no significant glucose fluctuation. Rats in Sham group were normally fed. Rats in treated group received 2 ng/kg Exendin-4 intervention, at 2, 4, 6 and 8 weeks after intervention, TUNEL staining and qRT-PCR were performed to examine apoptosis of beta-cells and insulin expression, respectively. Compared with DM group, insulin expression of treated group increased significantly (P<0.05). 80 rats were successfully performed with type I diabetes, fasting blood-glucose was maintained at 30 mmol/L for four consecutive weeks. Results at different time showed apoptosis of beta-cells was reduced gradually after Exendin-4 intervention. Exendin-4 intervention inhibits apoptosis of beta-cells effectively in type I diabetes, elevates expression of insulin, and its effect increases with intervention time. This suggested Exendin-4 had promising efficacy and benefit for type I diabetes treatment and was worth of being generalized.