OBJECTIVETo investigate the effects of low-dose simvastatin on the expression of connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA) in the renal tubulointerstitium of rats with diabetic nephropathy.

METHODSSixty male SD rats were randomly divided into three groups: Group C (control group), Group D, in which diabetes was induced by stroptozotocin (STZ) and Group DS, in which STZ-induced diabetic rats were treated with low-dose (no cholesterol-lowering effect) simvastatin. The following parameters were measured after 6 weeks and 12 weeks in each groups, respectively: body weight and kidney weight, 24-h urinary albumin excretion (UAE), biochemical indexes including blood glucose (GLU), low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (TG) and serum creatinine (SCr). The expression of CTGF and α-SMA in renal tubulointerstitium was assessed by immunohistochemical method.

RESULTAfter 6 and 12 weeks, there were no significant differences in SCr, LDL, HDL and TG levels among all three groups. The expression levels of CTGF and α-SMA in the tubulointerstitium of Group DS were significantly decreased compared with those of Group D at week 6 (P<0.05); there were no significant differences compared with Group C (P>0.05). After 12 weeks, CTGF and α-SMA expressions in Group DS were also lower than those in Group D (P<0.05); while higher than those in Group C (P<0.05).

CONCLUSIONSimvastatin with a under cholesterol-lowering dose, can decrease the expression levels of CTGF and α-SMA in renal tubulointerstitium of rats with diabetic nephropathy, by which the progression of the tubulointerstitial fibrosis would be delayed.