Metformin alleviates renal injury in diabetic rats by inducing Sirt1/FoxO1 autophagic signal axis

Diabetic nephropathy (DN) is the major microvascular complication of diabetes mellitus and the most important cause of end-stage renal disease worldwide. Metformin is the preferred oral hypoglycaemic drug for type 2 diabetes mellitus (T2DM). Recent studies have shown that besides lowering blood glucose, metformin also has protective effects on renal function, but its mechanism is not clear. In this study, we established a diabetic rat model by high-fat feeding combined with intraperitoneal injection of streptozotocin. Their changes of renal function, oxidative stress, histopathology and structure, and autophagy were observed after 8 weeks of metformin treatment at different dose. Sirt1 inhibitor EX527 and metformin were used to observe whether the protective effect of metformin on DN kidney was achieved through the Sirt1/FoxO1 autophagic signalling pathway. The results showed that metformin could protect renal function by up-regulating autophagy level, alleviating oxidative stress level of renal tissue and pathological and structural changes of glomeruli, and inhibiting the expression of extracellular matrix. Sirt1 inhibitor could block the protective effect of metformin on kidney of diabetic rats, suggesting that metformin could alleviate kidney injury in diabetic rats by inducing Sirt1/FoxO1 autophagy signal axis. So metformin could alleviate renal injury in diabetic rats, which may be achieved by regulating Sirt1/FoxO1 autophagic signalling pathway and inducing renal autophagy.