Berberine ameliorates renal impairment and inhibits podocyte dysfunction by targeting the phosphatidylinositol 3‐kinase–protein kinase B pathway in diabetic rats

Abstract Aims/Introduction Amelioration of renal impairment is the key to diabetic nephropathy ( DN ) therapy. The progression of DN is closely related to podocyte dysfunction, but the detailed mechanism has not yet been clarified. The present study aimed to explore the renal impairment amelioration effect of berberine and related mechanisms targeting podocyte dysfunction under the diabetic state. Materials and Methods Streptozotocin (35 mg/kg) was used to develop a DN rat model together with a high‐glucose/high‐lipid diet. Renal functional parameters and glomerular ultrastructure changes were recorded. The alterations of phosphatidylinositol 3‐kinase (PI 3K), protein kinase B (Akt) and phosphorylated Akt in the kidney cortex were determined by western blot. Meanwhile, podocyte dysfunction was induced and treated with berberine and LY 294002. After that, podocyte adhesion functional parameters, protein biomarker and the alterations of the PI 3K–Akt pathway were detected. Results Berberine reduces the increased levels of biochemical indicators, and significantly improves the abnormal expression of PI 3K, Akt and phosphorylated Akt in a rat kidney model. In vitro , a costimulating factor could obviously reduce the podocyte adhesion activity, including decreased expression of nephrin, podocin and adhesion molecule α3β1 levels, to induce podocyte dysfunction, and the trends were markedly reversed by berberine and LY 294002 therapy. Furthermore, reduction of PI 3K and phosphorylated Akt levels were observed in the berberine (30 and 60 μmol/L) and LY 294002 (40 μmol/L) treatment group, but the Akt protein expression showed little change. Conclusions Berberine could be a promising antidiabetic nephropathy drug through ameliorating renal impairment and inhibiting podocyte dysfunction in diabetic rats, and the underlying molecular mechanisms might be involved in the regulation of the PI 3K–Akt signaling pathway.