Trapa Bispinosa Roxb. Inhibits the Insulin-Dependent AKT/WNK1 Pathway to Induce Autophagy in Mice with Type 2 Diabetes

PURPOSE: To elucidate the antiglycation activity of Trapa bispinosa Roxb. extract (TBE) and the related mechanism using a mouse model with type 2 diabetes. MATERIALS AND METHODS: We prepared control mice by giving them a normal diet, leptin-deficient ob/ob mouse (ob/ob mice) with a normal diet (normal ob/ob mice), and ob/ob mice with a diet containing TBE (TBE ob/ob mice). The effect of TBE on diabetic retina was evaluated by immunohistochemical staining and quantitative real-time polymerase chain reaction (qPCR) analysis. RESULTS: In both groups with ob/ob mice, body weight and hyperglycemia levels increased over time. Immunohistochemical staining analysis revealed that glial fibrillary acidic protein (GFAP) and advanced glycation end products (AGEs) expression levels were higher in normal ob/ob mice than in control mice, and lower in the TBE ob/ob mice than in normal ob/ob mice. Light chain-3 (LC-3) expression levels reduced in normal ob/ob mice compared to the control mice, but increased in TBE ob/ob mice compared to normal ob/ob mice. In the qPCR analysis, LC-3 expression levels were significantly lower in normal ob/ob mice compared to control mice, and significantly higher in TBE ob/ob mice compared to normal ob/ob mice. Conversely, AKT1 and with-no-lysine kinases 1 (WNK1) expression levels were significantly higher in normal ob/ob mice compared to control mice, and significantly lower in TBE ob/ob mice than in normal ob/ob mice. CONCLUSION: In type 2 diabetes, it was suggested that TBE inhibits the insulin-dependent AKT/WNK1 pathway to induce autophagy, and thereby might promote anti-glycation and reduce retinal damage.