Regulation of the Ku70 and apoptosis-related proteins in experimental diabetic nephropathy.

BACKGROUND: Apoptosis contributes nephropathy pathogenesis in diabetes. However, its mechanisms still remain unclear. We examined the extent to which the angiotensin-II type 1 receptor blocker (AT1RB) irbesartan and the angiotensin converting enzyme inhibitor (ACEI) perindopril affected the apoptosis-related proteins Bcl-2, Bax, caspase-3, cytochrome-c and Ku70 in streptozotocin (STZ)-diabetic rats.

MATERIALS AND METHODS: Animals were divided into five groups of eight each, four of which received STZ (60mg/kg in a single dose, i.p.) to induce diabetes. The groups were performed as untreated diabetic; non-diabetic control; daily irbesartan (15mg/kg/day) or perindopril (6mg/kg/day) and also combined irbesartan and perindopril (respectively, 5mg/kg/day, 3mg/kg/day) were applied by gavage for 30days to STZ-diabetic rats. The kidney tissue analysis was performed by using immunohistochemical staining with Bcl-2, Bax, caspase-3, cytochrome-c and Ku70 antibodies and by using Western blot analysis with caspase-3 and cytochrome-c antibodies.

RESULTS: Immunoreactivity of Bax, caspase-3, cytochrome-c and Ku70 was increased in the tubuli and glomeruli of the untreated diabetic group, but decreased in all treated diabetic groups. In the irbesartan and perindopril treated diabetic groups Bcl-2 immunoreactivity was higher than that of the untreated diabetic group. Caspase-3 and cytoplasmic cytochrome-c protein levels increased in the untreated diabetic group.

CONCLUSIONS: We conclude that the increased expression of Bax and caspase-3, and the increased level of cytoplasmic cytochrome-c relate to renal tissue injury. This case is also seen in the early stages of diabetes as a result of the damage caused by local increased expression of renin angiotensin system (RAS) in the renal tissue, which is induced by hyperglycemia. The increase of the cytosolic cytochrome-c, caspase-3 and Ku70 expression in the tubuli is suggestive of apoptosis. Overall, our results show that treatments of irbesartan and perindopril are effective and efficient in preventing renal tissue injury and apoptosis by blocking the RAS in experimental diabetic nephropathy and reducing the expression of proteins associated with apoptosis.