Intervention of hydrogen on memory damage induced by chronic hypoxia-hypercapnia in rats

AIM: To investigate the effects of hydrogen on the memory damage caused by chronic hypoxia-hypercapnia in rats. METHODS: Twenty-four SD rats trained by eight-arm radial maze test were randomly divided into 3 groups:normal control group (NC), hypoxia-hypercapnia+saline group (MS) and hypoxia-hypercapnia+ hydrogen group (MH). The rats in the latter 2 groups were placed in a closed cabin for 8 h/day,6 days/week and lasted for 4 weeks, in which O₂ was 9％-11％ and CO₂ was 5％-6％. In every time after the animals were out of the cabin, the MS rats were intraperitoneally injected with saline (5 mL/kg) and the MH rats were intraperitoneally injected with hydrogen solution at the same dose. The learning and memory function, the activity of superoxide dismutase (SOD), the content of malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) were examined after the cabin training. The ultramicrostructures of hippocampus were also observed. RESULTS: (1) Compared with NC group, the number of working memory errors, the total errors, the content of hippocampus 8-OHdG and serum MDA in MS and MH groups were higher and the activity of serum SOD was lower (P<0.05). The hippocampus structure was destroyed and some degree of edema and more apoptosis in the neurons were obserued in MS group and MH group. (2) Compared with MS group, the number of working memory errors(WME), the total errors, the content of hippocampus 8-OHdG and serum MDA were lower and the activity of serum SOD was higher in MH group (P<0.05). In MH group, the morphology of hippocampus structures kept nearly normal arrangement and the only mild edema and fewer apoptosis in the neurons were found. CONCLUSION: Hydrogen may attenuate chronic hypoxia-hypercapnia-induced memory damage in rats by inhibiting apoptosis of the neurons and decreasing detrimental free radicals reaction.