ObjectiveTo observe the effects of Tongluo recipe on extracellular signal-regulated protein kinase (ERK1/2) pathway in the kidneys of streptozotocin-induced rat models of type 1 diabetes mellitus, and to explore the renoprotective mechanism of Tongluo recipe. MethodsAdult male Sprague-Dawley rats were randomly divided into 2 groups: control group(A, n=10) and experimental group. Rats in the experimental group were induced by intraperitoneal injection of streptozotocin (60 mg/kg body mass), and were randomly subdivided into group B (diabetic control, n=10), group C (diabetic rats treated with low dose of Tongluo recipe,0.5 g/\[kg·d\], n=10), group D (diabetic rats treated with medium dose of Tongluo recipe,1.0 g/\[kg·d\], n=10), group E (diabetic rats treated with high dose of Tongluo recipe,2.0 g/\[kg·d\], n=10) and group F (diabetic rats treated with losartan, 30 mg/\[kg·d\],n=10). At the end of the 12th week rats were sacrificed, and the serum glucose, triacylglycerol(TG), total cholesterol(Chol), serum creatinine(Scr), urea nitrogen(BUN) in blood, 24-hour urine protein(Upro24), microalbuminuria (MAU), and creatinine in urine(UCR) were examined. The kidney mass/body mass (KM/BM) and creatinine clearance rate (Ccr) were calculated. The left kidneys were collected, weighed and subjected to H-E staining and PAS staining to observe the pathological changes; serum and renal tissue angiotensin Ⅱ(Ang Ⅱ) levels were determined by ELISA; the expression of phosphorylated ERK1/2(p-ERK1/2) was detected by immunohistochemical staining and vascular endothelial growth factor(VEGF) protein expression was determined by Western blotting analysis. ResultsCompared with group B, group D had a slighter mesangial proliferation under light microscope. Besides, rats in group D had significantly decreased Ccr, BUN, MAU, and Upro24 in the serum, and decreased Ang Ⅱ in the serum and renal tissue, and decreased KM/BM, VEGF and p-ERK1/2 levels in renal tissue compared with rats in group B(P<0.05). The medium dose of Tongluo recipe and losartan showed similar effects in improving the renal function and inhibiting Ang Ⅱ, VEGF, and p-ERK1/2 expression of diabetic rats. ConclusionThe renoprotective effect of Tongluo recipe may be related to inhibition of ERK1/2 cascade pathway by decreasing the expression of Ang Ⅱ and VEGF.