Regulatory effect of berberine on unbalanced expressions of renal tissue TGF-beta1/SnoN and smad signaling pathway in rats with early diabetic nephropathy

Objective: To investigate the effect of berberine (BBR) on unbalanced expression of renal tissue TGF-beta1/SnoN and Smad signal pathway in rats with early diabetic nephropathy (DN), and discuss BBR's effect on DN rats with early diabetic nephropathy and its possible mechanism.

Methods: DN rat model were established by injecting streptozotocin (STZ). The rats were divided into six groups: the control group, the model group, three BBR (50, 100, 200 mg x kg(-1)) treatment groups and the enalapril treatment group. They were orally administered once a day for five weeks. The fasting blood glucose (FBG), blood urea nitrogen (BUN), serum creatinine (Scr), urinary protein (24 h Upro) and urinary microalbumin (24 h UmAlb) were tested. The pathological changes in renal tissues were examined by optical microscopy. Immunohistochemical measures were used to detect the expressions of TGF-beta1, SnoN, Smad2/3 and Smad7 protein, and RT-PCR was used to detect TGF-beta1 mRNA in renal tissues.

Results: Compared with the model group, BBR-treated groups showed significant decrease in FBG, BUN, Scr, 24 h Upro, 24 h UmAlb, TGF-beta1 protein, mRNA and Smad2/3 protein, abnormal morphological improvement in renal tissues, and notable increase in the expressions of SnoN and Smad7 protein.

Conclusions: BBR can maintain the dynamic balance in TGF-beta1/SnoN expression in renal tissues through Smad signaling pathway, so as to mitigate renal functional disorder in DN rats and delay DN and its development.