Pueraria tuberosa extract inhibits iNOS and IL-6 through suppression of PKC-α and NF-kB pathway in diabetes-induced nephropathy.

Abstract

Inflammation plays an important role in the pathogenesis of diabetic nephropathy (DN). The aim of this study was to explore the anti-inflammatory role of PTY-2r (extracted from Pueraria tuberosa), on streptozotocin (STZ)-induced DN rats. Diabetes was induced by intraperitoneal injection of STZ (55mg/kg) in rats. After 60days, the rats were randomly divided into three groups (n=6/each group), namely DN control group 2, DN rats treated with PTY-2r at dose of 100mg/100g, group 3 and 50mg/100g, group 4, p.o for 20days. The normal rats were chosen as a normal control (NC) group 1. In DN rats, the expression of iNOS and inflammatory cytokines (IL-6 and TNF-α) was significantly increased. Raised expression of PKC-α was also found. As NF-kB is the main transcription factor for the inflammatory response-mediated progression of DN, variation in NF-kB expression and its activated phosphorylated derivative (pNF-kB) were also evaluated and increase in expression was obtained in the kidney of DN rats. PTY-2r treatment significantly reversed these changes in dose-dependent manner. This study suggested that the nephroprotective effect of PTY-2r is possibly due to downregulation of PKC-α and NF-kB pathway and normalizing the expression of inflammatory cytokines and iNOS in the kidney of DN rats.