Diazoxide protects against hydrogen peroxide-induced toxicity in the osteoblastic MC3T3-E1 cells

Abstract

Treatment of various types of cells with the mitochondrial ATP-sensitive K + channel (mK ATP) opener has been shown to precondition cells to subsequent injuries and inhibit apoptosis. We exposed cultured osteoblastic MC3T3-E1 cells to hydrogen peroxide (H 2O 2) with or without pretreatment with a mK ATP opener, diazoxide. A marked decrease in osteoblast viability was evident after 48 h exposure of 0.3 mM H 2O 2, compared with vehicle-treated cells. Diazoxide (0.001 ~ 10 μM) treatment significantly ( P < 0.05) reversed the cytotoxic effect of H 2O 2 and this effect was blocked by a specific mK ATP blocker, glibenclamide. Pretreatment with diazoxide (0.01 ~ 1 μM) also decreased the release of reactive oxygen species and the increase in oxidative damage markers (protein carbonyl and malondialdehyde) induced by H 2O 2 in osteoblastic MC3T3-E1 cells. Moreover, H 2O 2-induced reduction of differentiation markers, such as alkaline phosphatase, collagen content and calcium deposition was significantly recovered in the presence of diazoxide. In addition, diazoxide (0.01 ~ 1 μM) decreased the H 2O 2-induced production of osteoclast differentiation-inducing factors, such as interleukin (IL)-6 and the receptor activator of nuclear factor-kB ligand (RANKL). These results suggest that diazoxide may be useful for the protection of H 2O 2-induced oxidative damage and dysfunction in osteoblastic cells.