Protective effect of simvastatin on kidney of rats with diabetes mellitus and the possible mechanism

Abstract

To observe the protective effect of simvastatin on renal injury in diabetic rats and to explore the possible molecular mechanism. Twenty-four SD rats were randomly divided into normal control (NC) group (n=8) and modeling group (n=16).The rats in modeling group were injected with streptozotocin intraperitoneally at a dose of 55 mg/kg to establishing diabetic rat model. After diabetic ratmodel established successfully, the diabetic rats were randomly subdivided into diabetes mellitus (DM) group and diabetes mellitus + simvastatin (DM+Sim) group (n=8).Rats in DM+Sim group were given simvastatin at a dose of 40 mg/kg by oral gavages, once a day for 4 weeks. Morphological changes and interstitial fibrosis of kidney were observed by histopathological method. The expressions of relative protein in endoplasmic reticulum stress, inflammatory molecules in renal tissues and cells apoptosis were detected by molecular biology method. ① Compared with NC group, the pathological changes of glomerulus and tubulointerstitium were obvious, and the collagen fibers were obviously erythrophilous and unevenly distributed in DM group. Compared with DM group, the morphological changes and fibrosis were significantly improved in DM+Sim group. ② The expressions of GRP78, p-IRE1α, NF-κB p65 and MCP-1 in DM group were significantly higher than those in NC group (P<0.05), while the expressions of GRP78, p-IRE1α, NF-κB p65 and MCP-1in DM + Sim group were decreased (P<0.05). ③ There were a small number of apoptotic nuclei in the glomeruli and adjunctive renal tubules in NC group detected by TUNEL assay, while there were a large number of apoptotic nuclei in DM group (P<0.01). The number of apoptotic nuclei was decreased significantly in DM+Sim group (P<0.01). Morphologicalchanges and fibrosis of renal tissue are improved obviously, and the number of apoptotic cells is decreased significantly after administration of simvastatin in diabetic rats. Simvastatin exertsthe protective effect on diabetic nephropathy by inhibiting endoplasmic reticulum stress and NF-κB inflammatory signaling pathway, and reducing renal cell apoptosis.