Objective:To explore the effects of hydroxy-methyl-glutaryl coenzymeA reductase inhibitor (HMG-CoA RI) simvastatin on renal expression of apoptosis related gene Fas/Fas-L in aged diabetic rats after uninephrectomy.Methods: Elderly uninephrectomized SD rats were randomly divided into uninephrectomized control group (group C),streptozocin(STZ)-induced diabetic model group( group D),and diabetes + simvastatin group (group S).The apoptosis indices in renal tisses of three groups were detected by terminal deoxynucleotide mediated nick end labeling 12 weeks later.Immunofluorescence and real-time quantitative PCR were employed to observe the expression changes of Fas/Fas-L genes at the transcription and translation levels.Results: Compared with group C,group D had significantly higher apoptosis index and expression level of Fas/Fas-L; the above parameters were lower in group S compared with those in group D (P<0.05).The expression of Fas/Fas-L protein was mainly in the renal tubules.Conclusion:Both Fas and Fas-L genes are associated with the development and progression of diabetic nephropathy in aged rats.Simvastatin can down-regulate the translation and transcription of the genes,inhibit cell apoptosis and protect the kidney.