Hepatic oxidative stress in an animal model of sleep apnoea: effects of different duration of exposure

BACKGROUND: Repeated apnoea events cause intermittent hypoxia (IH), which alters the function of various systems and produces free radicals and oxidative stress. METHODS: We investigated hepatic oxidative stress in adult mice subjected to intermittent hypoxia, simulating sleep apnoea. Three groups were submitted to 21 days of IH (IH-21), 35 days of IH (IH-35), or 35 days of sham IH. We assessed the oxidative damage to lipids by TBARS and to DNA by comet assay; hepatic tissue inflammation was assessed in HE-stained slides. Antioxidants were gauged by catalase, superoxide dismutase, glutathione peroxidase activity and by total glutathione. RESULTS: After IH-21, no significant change was observed in hepatic oxidative stress. After IH-35, significant oxidative stress, lipid peroxidation, DNA damage and reduction of endogenous antioxidants were detected. CONCLUSIONS: In an animal model of sleep apnoea, intermittent hypoxia causes liver damage due to oxidative stress after 35 days, but not after 21 days.