Changes in enzymatic antioxidant activity in pregnant rats exposed to hyperoxia or hypoxia.

Pregnant rats were exposed to chronic hyperoxia or hypoxia to examine whether endogenous (pregnancy) and external (exposure to environmental) oxidative stresses have additive influences on inducing enzymatic antioxidant activity (EAOA). The activities of catalase, glutathione peroxidase (GPx) and superoxide dismutase (SOD) were measured in the brain, liver, lungs, heart, uterus and placenta in non-pregnant (N) and pregnant (P) rats after 1 week of exposure to normoxia, hyperoxia and hypoxia. An additional combined effect in EAOA was found only in the heart. In the lungs and liver, EAOA increased both in pregnancy and hyperoxia, but no additive combined effect was noticed. The brain and N uterus EAOA were not influenced by pregnancy or hyperoxia. In the placenta, only SOD and GPx activities increased. Hypoxia had a negligible effect on EAOA both in N and P rats. Generally, the EAOA response of P rats to environmental oxidative stress was higher than that of N rats. We conclude that the influence of pregnancy and external oxidative stress on EAOA are not simply additive.