The mechanism of periventricular leukomalacia onset

Some brain damages in the newborn has been induced not by perinatal asphyxia but by some perinatal complications, such as preterm delivery and infection. However, the exact mechnism that induces brain damages, expecially periventricular leukomalacia in the newborn has not been clarified. Adenosine, one of purine metabolites, is a potent vasodilator and has strong brain protective action. The physiological roles and metabolism of adenosine in the human fetuses has not been well investigated. In this research, we measured fetal plasma adenosine concentration in various pathophysical conditions that sometimes induced brain damage in complicated pregnancies, such as IUGR and preeclampsia. We then evaluated the relationship between plasma adenosine concentration and fetal PO_2, pCO_2, pH,breathing movements, fetoplacental circulation. Plasma adenosine concentraion was elevated significantly in IUGR fetuses, and which inversely correlated with fetal PO_2 and pH.An elevation of plasma adenosine concentration was related to the decrease of fetal breathing movements. Moreover, the production of adenosine in fetoplacental circulation was enhanced during uteroplacental ischemia. Our results suggest that adenosine may play an important role in prevention of brain damage in fetuses.