Effect of intrauterine ischemia-hypoxia on endothelial nitric oxide synthase in fetal brain in rats.

Nitric oxide (NO) plays important roles in the regulation of cerebral blood flow (CBF) in the perinatal period. The present study was undertaken to investigate the influence of intrauterine ischemia-hypoxia (IH) on the expression of endothelial NO synthase (eNOS) in fetal brains in rats. To induce intrauterine IH insult, bilateral uterine arteries were ligated on day 17 of pregnancy. Activities and mRNA levels in the brain of the fetuses were examined on days 17-21 of pregnancy. The IH insult caused the increase in both activities and mRNA levels of eNOS on day 21 of pregnancy, whereas there were no significant changes in neuronal NOS mRNA levels. Endothelial NOS expression in the fetal brains was increased by intrauterine IH insult, suggesting that eNOS may contribute to the maintenance of CBF against ischemia or hypoxia conditions in the fetal rats.