Effect of different methods of hypoxic exercise training on free radical oxidation and antioxidant enzyme activity in the rat brain

The effects of different modes of hypoxic exercise training on free radical production and antioxidant enzyme activity in the brain of rats were investigated in this study. A total of 40 healthy 2-month-old male Wister rats were randomly assigned to 5 groups according to different training modes. Endurance training sessions were performed for 5 weeks under different normoxic (atmospheric pressure similar to 632 mmHg, altitude similar to 1,500 m) and hypoxic conditions (atmospheric pressure similar to 493 mmHg, altitude similar to 3,500 m) at the same relative intensity. The superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activity and the malondialdehyde (MDA) content of the brain were evaluated by spectrophotometric analysis. Compared to the low-training low (LL) group, the SOD activity was significantly increased by 68.73, 54.28 and 304.02% in the high-training high (HH), high-training low (HL) and high-exercise high-training low (HHL) groups, respectively. However, no obvious change was observed for the low-training high (LH) group. In comparison to the LL group, the GSH-Px activity was found to be significantly higher in the HH, HL, LH and HHL groups. Similarly, in comparison to the LL group, the CAT activity exhibited a significant increase in the HH, HL, LH and HHL groups. Compared to the LL group, the MDA content was significantly increased in the HH, HL and HHL groups, although no significant difference was detected for the LH group. Following exhaustive exercise, the antioxidant enzyme activities in the rat brains were immediately improved in all the hypoxia modes. Moreover, the free radical production was increased after all the modes of hypoxic exercise training, with the LH mode being the only exception.