Renal Protective Effect of Melatonin in Diabetic Rats

【Objectives】To investigate the mechanism of melatonin in protecting the renal lesion of diabetic rats. 【Methods】Experimental diabetic rats were induced by peritoneal injection of streptozotocin. The rats were randomly divided into following groups: normal control rats (group C), streptozotocin-induced diabetic rats (group D) and diabetic rats treated with melatonin (group M). After 4 weeks, the serum creatinine, kidney hypertrophy index (kidney weight/body weight ratio), and 24h urinary albumin excretion rate were measured, respectively. TGF-β1 mRNA expression in renal cortex of rats using newly real-time quantitative RT-PCR with SYBR Green Ⅰ and the kidney samples were observed with light microscope, mean glomerular transverse sectional area (MGA) and mean glomerular volume (MGV) were also calculated by analysis system of the image. 【Results】 After 4 weeks, kidney hypertrophy index and 24h urinary albumin excretion of melatonin treatment group were significantly lower than those in diabetic group D (P＜0.01). TGF-β1 mRNA expression levels revealed a 9.2-fold increase in diabetic glomeruli after four weeks compared to normal glomeruli (P＜0.01). While melatonin treatment decrease 3.95-fold, but still significantly higher compared to normal glomeruli (P＜0.01). Furthermore, the MGA and MGV in group M were significantly smaller than those of group D (P＜0.01). 【Conclusion】 Melatonin possesses a renal protective effect on diabetic rats, whose mechanism may be associated partly with a down-regulation of the expression of TGF-β1 mRNA.