The mitochondrial permeability transition contributes to acute ethanol-induced apoptosis in rat hepatocytes

Acute ethanol intoxication induces oxidative stress and apoptosis in primar y cultured hepatocytes. Oxidative stress can trigger mitochondrial cytochro me c release initiating the mitochondrial pathway of apoptosis. Based on th is information, we formulated the hypothesis that ethanol-induced oxidative stress causes mitochondrial dysfunction resulting in apoptosis. In the pre sent study, we found that the mitochondrial membrane permeability transitio n (MPT) is essential for induction of mitochondrial cytochrome c release an d caspase activation of ethanol. The short-term incubation with ethanol (50 mmol/L) induced the MPT, cytochrome c release, caspase activation, and apo ptosis of cultured rat hepatocytes. Hepatocyte apoptosis was prevented by c aspase inhibitors (i.e., Z-VAD-fmk, DEVD-cho, and DMQD-cho). An MPT inhibit or, cyclosporin A, also prevented ethanol-induced cytochrome c release, cas pase activation, and apoptosis, suggesting that acute ethanol-induced apopt osis is MPT dependent. Ethanol-induced MPT was also attenuated by N'N-dimet hylthiourea (DMTU, a scavenger of hydrogen peroxide, 10 mmol/L) and N-acety l-cysteine (NAC, an antioxidant, 5 mmol/L). Preventing hepatocyte MPT by DM TU or NAC attenuated cytochrome c release as well as caspase activation, su ggesting that ethanol-induced oxidative stress mediates the MPT. Thus, acut e ethanol induces MPT via oxidative stress, and the MPT mediates mitochondr ial pathway of apoptosis in hepatocytes exposed to acute ethanol.