Schisandra chinensis fruit extract attenuates albuminuria and protects podocyte integrity in a mouse model of streptozotocin-induced diabetic nephropathy

Ethnopharmacological relevance: Schisandra chinensis fruit is widely used in Chinese medicine for the treatment of hepatic, renal, heart, cerebrovascular and infectious diseases. Aim of the study: To investigate the effects of Schisandra chinensis fruit extract (SE) on albuminuria and podocyte injury as well as the underlying mechanism in the mouse model of streptozotocin (STZ)-induced diabetic nephropathy and in cultured mouse podocyte cells. Materials and methods: SE was orally administrated in STZ-induced diabetic nephropathy mice for 7 weeks, at a daily dose of 5 g/kg body weight. The urinary albumin/creatinine ratio and urine albumin excretion rate were measured at the 6th and 9th week of the experiment. The extent of glomerulosclerosis and extracellular matrix deposition were determined by periodic acid-silver methenamine and Masson's trichrome staining. The amount of podocytes and the integrity of the slit diaphragm were detected by immunohistological staining of podocyte markers, Wilms' tumor 1 and nephrin. Alpha-smooth muscle actin, E-cadherin and plasminogen activator inhibitor-1 were measured by western blot and immunohistological staining to evaluate the level of epithelial-to-mesenchymal transition (EMT). Real-time reverse transcription PCR was used to detect the mRNA level of E-cadherin, alpha-SMA and snail in cultured podocyte cells. Results: Treatment with SE significantly decreased the urine albumin excretion rate and urinary albumin/creatinine ratio. In addition, SE attenuated glomerulosclerosis and protected against podocyte loss and integrity of the slit diaphragm. Furthermore, SE effectively prevented the EMT of podocytes caused by diabetic nephropathy. Conclusions: Our studies suggest that SE might be beneficial for diabetic nephropathy. The effects of SE on attenuating albuminuria and glomerulosclerosis are possibly mediated by preserving podocyte integrity through suppressing EMT. (C) 2012 Elsevier Ireland Ltd. All rights reserved.