Protective potential of glutathione peroxidase-1 gene against cocaine-induced acute hepatotoxic consequences in mice.

Since the cocaine-induced oxidative stress has been established to lead to hepatotoxicity, we examined the role of the glutathione peroxidase (GPx)-1 gene in cocaine-induced hepatotoxicity. Cocaine treatment significantly increased superoxide dismutase activity in as little as 1 hour, with a maximum level at 6 hours in wild-type mice, while significantly decreasing GPx activity and subsequently inducing oxidative damage (i.e., reactive oxygen species, lipid peroxidation and protein carbonylation). These changes were more prominent in the mitochondrial fraction than in the cytosolic fraction. In contrast, genetic overexpression of GPx-1 significantly attenuated cocaine-induced oxidative damage in mice. Cocaine treatment significantly increased alanine aminotransferase and aspartate aminotransferase levels in the serum. Consistently, cocaine significantly enhanced cleaved caspase-3 expression and intramitochondrial Ca2+ , while significantly reducing mitochondrial transmembrane potential. Cocaine treatment potentiated cleavage of protein kinase C δ (PKCδ), mitochondrial translocation of PKCδ, cytosolic release of cytochrome c and activation of caspase-3, followed by hepatopathologic changes. These results were more prominent in GPx-1 knockout than in wild-type mice, and they were less pronounced in overexpressing transgenic than in non-transgenic mice. Combined, our results suggest that the GPx-1 gene possesses protective potential against mitochondrial oxidative burden, mitochondrial dysfunction and hepatic degeneration induced by cocaine and that the protective mechanisms are associated with anti-apoptotic activity via inactivation of PKCδ.