Abstract: Objective: To explore the inhibitory function of Cordyceps militaris on the development of nephropathy in diabetic rats. Methods: Diabetic rat model was established by intraperitoneally injecting streptozotocin at the dose of 60 mg/kg. After the diabetic rats were administered with Cordyceps militaris at the dose of 400 mg/kg for 8 consecutive weeks, fasting blood glucose level, kidney index, the contents of microalbumin (mAlb) and β-N acetyl glucosaminidase (NAG) in urine, and the contents of blood urea nitrogen (BUN), creatinine (Cr) and uric acid (UA) in serum were determined. The mRNA expression of transforming growth factor-β1 (TGF-β1), transforming growth factor beta-receptor II (TGFβR II) and connective tissue growth factor (CTGF) in the kidney were evaluated by semi-quantitative RT-PCR. The expression of collagen IV and TGF-β1 protein in the kidney was determined by immunohistochemistry and Western blot analysis. Results: C. militaris could significantly reduce fasting blood glucose (P＜0.05), kidney index (P＜0.01), 24-h urine collection (P＜0.01), the excretion of mAlb (P＜0.01) and NAG (P＜0.01) in urine, and serum BUN, Cr and UA levels (P＜0.05) of diabetic rats. C. militaris administration resulted in a remarkably down-regulation of TGF-β1, TGFβR II and CTGF mRNA expression in the kidney of diabetic rats (P＜0.01). Western blot and immunohistochemistry analyses revealed a reduction in the expression of TGF-β1 and collagen IV protein due to C. militaris administration. Conclusion: C. militaris has anti-hyperglycemic function and can improve kidney filtration function. The mechanisms of these functions may be due to the inhibited expression of TGF-β1, TGFβR II and CTGF as well as the reduced accumulation of collagen in the mouse kidney.

Key words: C. militaris, diabetic nephropathy, TGF-β1, connective tissue growth factor(CTGF), collagen IV