Antidiabetic and protective effects of Scrophularia striata ethanolic extract on diabetic nephropathy via suppression of RAGE and S100A8 expression in kidney tissues of streptozotocin-induced diabetic rats.

Background The present study was conducted to examine the antidiabetic effects of Scrophularia striata ethanolic extract and to evaluate its effects on oxidative stress markers and RAGE and S100A8 gene expressions in the kidney of type 1 diabetic rats. Methods A total of 36 rats (weight 200-250 g) were randomly assigned into six groups as follows: Cnt, Cnt + S. striata 100, and Cnt + S. striata 200 that received normal saline, 100 mg/kg bw, and 200 mg/kg bw of ethanol extract of S. striata, respectively; and group Dibt, Dibt + S. striata 100, and Dibt + S. striata 200 that received normal saline, 100 mg/kg bw, and 200 mg/kg bw of ethanol extract of S. striata, respectively. Type 1 diabetes was induced in rats by a single injection of streptozotocin (55 mg/kg bw). After 60 days of treatment, biochemical factors and oxidative stress markers (superoxide dismutase [SOD] and malondialdehyde [MDA]) were measured using spectrophotometric methods. RAGE and S100A8 gene expressions were analyzed using real-time polymerase chain reaction. Results Diabetes significantly impairs serum and urine fasting blood glucose (FBG), lipid profile, creatinine, urea, and albumin parameters. After the treatment with S. striata extract, these parameters are close to the normal range. It was shown that the S. striata extract significantly decreased the kidney expression levels of RAGE and S100A8 genes and improved oxidative stress markers (SOD and MDA) in the kidney tissues when compared with the diabetic control group. It was also found that the beneficial effects of the S. striata were dose dependent. Conclusions The ethanolic extract of S. striata has beneficial antidiabetic effects. Moreover, by reducing RAGE and S100A8 gene expressions and by improving oxidative stress, S. striata might be used as adjuvant treatment for diabetic complications.