Oxidative stress and antioxidant status in a lizard Phrynocephalus vlangalii at different altitudes or acclimated to hypoxia.

Oxidative stress is a major challenge for the survival of animals living on plateaus; however, lifelong exposure to high altitudes could generate certain adaptabilities which make them more tolerant to these environments. The aim of the present study was to compare the oxidative stress and antioxidant status between low altitude (LA, 2900m) and high altitude (HA, 4200m) populations of Phrynocephalus vlangalii. The results showed that malondialdehyde levels in the HA populations decreased significantly in the brain, but markedly increased in the muscle and had no significant difference in the liver compared to LA populations. The activity of catalase in the brain was much higher in HA than LA. Except for total antioxidant capacity and glutathione reductase, other antioxidants were similar between the two populations in livers. By contrast, the levels of most antioxidants in muscle decreased markedly with elevation. We also explored the effects of hypoxia on oxidative damage and antioxidant defenses in P. vlangalii. The lizards were acclimated in a simulated hypoxic chamber (15% O2 and 8% O2) for 6weeks. The results showed that in the 8% O2 group, the levels of malondialdehyde, catalase, glutathione and total antioxidant capacity in the brain, and malondialdehyde, catalase and superoxide dismutase in the liver were significantly higher than the 15% O2 group. These findings indicate that in this species the oxidative stress and antioxidant capacity are subject to altitude and hypoxia and this lizard may have acquired some ability to deal with the oxidative stress.