Subchronic perinatal asphyxia in rats: embryo-foetal assessment of a new model of oxidative stress during critical period of development.

Approximately 3% of annual births suffer from birth asphyxia and one million of these newborns die. The aim of this study was to develop a model for studying subchronic perinatal asphyxia (SPA) in rats. Pregnant animals were exposed to 10.5% O2 during sensitive stages of brain development for 4h a day. Biochemical variables were analysed immediately and 24h after asphyxia. SPA caused significant reduction of foetal weight, produced abnormalities of distal parts of the skeleton, and anomalies in the development of brain ventricles. Time-dependent changes were observed in several parameters indicating adjustment of the developing organism to the delivery. Whereas lactate was elevated immediately after asphyxia, glucose mirrored high energy needs 24h after the insult. Immunohistochemical examination of the placentas revealed overgrowth of acidic glycoconjugates in the extracellular matrix of vascular walls in the animals exposed to asphyxia. We observed the presence of muscle fibres in chorionic plate arteries and also in intraplacental arteries. The present model proved to be useful for the study of asphyxial conditions during pregnancy. As it is non-invasive and allows to control asphyxial conditions, it appears suitable for the screening and investigation of indicators of asphyxia in the mother and foetus.