An alcoholic binge causes massive degradation of hepatic mitochondrial DNAin mice

Background & Aims: Ethanol causes oxidative stress in the hepatic mitochond ria of experimental animals and mitochondrial DNA deletions in alcoholics. We postulated that ethanol intoxication may cause mitochondrial DNA strand breaks. Methods: Effects of an intragastric dose of ethanol (5 g/kg) on hep atic mitochondrial DNA levels, structure, and synthesis were determined by slot blot hybridization, Southern blot hybridization, and in vivo [H-3]thym idine incorporation, respectively. Results: Two hours after ethanol adminis tration, ethane exhalation (an index of lipid peroxidation) increased by 13 3%, although hepatic lipids were unchanged. Mitochondrial DNA was depleted by 51%. Its supercoiled form disappeared, whereas linearized forms increase d. Long polymerase chain reaction evidenced lesions blocking polymerase pro gress on the mitochondrial genome. Mitochondrial transcripts decreased. Sub sequently, [H-3]thymidine incorporation into mitochondrial DNA increased, a nd mitochondrial DNA levels were restored. In contrast, nuclear DNA was not fragmented and its [H-3]thymidine incorporation was unchanged. Liver ultra structure only showed inconstant mitochondrial lesions. Ethanol-induced mit ochondrial DNA depletion was prevented by 4-methylpyrazole, an inhibitor of ethanol metabolism, and attenuated by melatonin, an antioxidant. Conclusio ns: After an alcoholic binge, ethanol metabolism causes oxidative stress an d hepatic mitochondrial DNA degradation in mice. DNA strand breaks may be i nvolved in the development of mitochondrial DNA deletions in alcoholics.