Effects of gestational exercise on hyperoxia-induced brain damage in the newborn

Aim: Preterm infants encounter hyperoxia relatively early on as they leave the intrauterine environment earlier than expected, while also being exposed to a higher level of hyperoxic stress due to insufficiencies in their antioxidant defense mechanisms. With that in mind, we investigate whether running exercises performed during pregnancy can contribute to the development of tolerance to neonatal hyperoxic brain damage. Method: While two female rats maintained a sedentary pregnancy, one female rat performed the mandatory running exercise for 30 minutes for five days a week throughout the pregnancy. Following delivery, the sedentary rats and the exercised rat were kept together with their offspring for five days at oxygen concentrations above 80 percent in order to induce brain damage. The offspring were sacrificed on postnatal Day 7 and brain/body ratio measurements were obtained. Results: The brain/body ratios in the control, hyperoxia and exercise-hyperoxia groups were found to be median (IQR) 0.074(0.68-0.77), 0.065(0.06-0.067) and 0.064(0.060-0.068), respectively. The brain/body ratios of the offspring of the mothers in the hyperoxia group were found to be significantly lower than the control group (p=0.002), irrespective of exercise (p=0.007). No statistically significant difference was noted between the offspring of the sedentary and the exercised mothers in the hyperoxia group (p=0.94). Conclusion: Hyperoxia was found to result in lower brain mass relative to total body mass. This finding, which indicates the presence of microcephaly, reflects the negative effects of hyperoxia on brain development. Contrary to expectations, exercises performed during pregnancy had no significant effect on the brain/body weight ratio of the offspring.