Imidapril, an Angiotensin-Converting Enzyme Inhibitor, Reduces Diabetes-Induced Renal Oxidative Damage in Mice

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The aim of the present study was to determine whether imidapril, an angiotensin-converting enzyme inhibitor, prevents diabetic nephropathy and to determine the effect of imidapril on oxidative damage in the diabetic glomeruli in mice. We used female BKS.cg-m+Lepr^db/+Lepr^db (db/db) mice, a rodent model of type 2 diabetes, and their non-diabetic db/m littermates. The mice were divided into the following four groups: non-diabetic db/m, diabetic db/db, and diabetic db/db treated with imidapril at doses of 1 mg/kg and 5 mg/kg. Blood glucose level, body weight, urinary albumin, and urinary 8-hydroxydeoxyguanosine (8-OHdG) were measured during the experiments. Histological and 8-OHdG immunohistochemical studies were performed for 12 weeks from the beginning of treatment. After 12 weeks of treatment, the levels of blood glucose and the body weight were not significantly different between the imidapril-treated group and the non-treated db/db group. The systolic blood pressure was significantly increased in db/db mice compared with db/m mice. The increased blood pressure was significantly reduced by the treatment with imidapril at a dose of 5 mg/kg. The relative mesangial area calculated by the mesangial area/total glomerular area ratio was significantly ameliorated in the imidapril-treated group compared with the non-treated db/db group. The increases in urinary albumin and 8-OHdG at 12 weeks of treatment were significantly inhibited by chronic treatment with imidapril in a dose-dependent manner. The 8-OHdG immunoreactive cells in the glomeruli of non-treated db/db mice were more numerous than in the imidapril-treated db/db mice. In conclusion, imidapril prevented the progression of diabetic nephropathy in mice, not only by decreasing the glomerular pressure but also by decreasing the oxidative stress in glomerular cells.