Protective effect of ferulic acid on STZ-induced diabetic nephropathy in rats

Diabetic nephropathy (DN) is a major and severe complication of diabetes mellitus. Ferulic acid (FA), a phenolic compound widespread in fruits and plants, displays a variety of pharmacological activities including regulating blood glucose and lipids, anti-oxidation, anti-inflammation and anti-fibrosis. The study was aimed to investigate the renal protective effects of FA on diabetic rats and elucidate the underlying mechanisms. FA (100 mg kg^-1, i.g., once a day) was administered to DN rats for 8 weeks. The organ coefficient of kidneys was calculated. Levels of UP, BUN, Cr, FBG, TC and TG in serum were measured. Activities of SOD, CAT and GPx and the content of MDA in renal tissues were assayed. Pathological changes in renal tissues were observed by HE staining, PAS staining, PASM staining, Masson staining and transmission electron microscopy. p-NF-κB p65, TNF-α, TGF-β1, collagen IV, nephrin and podocin protein expressed in renal tissues were determined by immunohistochemistry and western blotting. Results showed that FA significantly improved the kidney organ coefficient, decreased the UP, BUN, Cr, FBG, TC and TG levels in serum, increased SOD, CAT and GPx activities, reduced MDA content in renal tissues and alleviated pathological injury of the renal tissues. What's more, long-term treatment with FA considerably down-regulated the expressions of p-NF-κB p65, TNF-α, TGF-β1 and collagen IV proteins, and up-regulated the expressions of nephrin and podocin proteins in renal tissues. FA could be a renoprotective agent by attenuating oxidative stress, inflammation, and fibrosis, as well as improving podocyte injury in STZ-induced DN rats.