Prenatal hypoxia impairs the postnatal development of neural and functional chemoafferent pathway in rat

1 To define the effects of prenatal hypoxia on the postnatal development of the chemoafferent pathway, ventilation and metabolism, pregnant rats were exposed to normobaric hypoxia (10 % oxygen) from embryonic day 5 to embryonic day 20. Offspring were studied at 1, 3 and 9 weeks of age in three separate protocols. 2 Prenatal hypoxia decreased the dopamine content in the carotid bodies at all ages, and decreased the utilisation rate of noradrenaline in the caudal part of the A 2 (A 2 c), A 1 and A 5 noradrenergic brainstem cell groups at 3 weeks after birth. At 9 weeks of age, the level of dopamine in the carotid bodies was still reduced but the utilisation rate of noradrenaline was enhanced in A 1 . 3 Rats from dams subjected to hypoxia during pregnancy hyperventilated until 3 weeks after birth. In these rats, the biphasic hypoxic ventilatory response was absent at 1 week and the increase in minute ventilation was amplified at 3 weeks. 4 Prenatal hypoxia disturbed the metabolism of offspring until 3 weeks after birth. A weak or absent hypometabolism in response to hypoxia was observed in these rats in contrast to control animals. 5 Prenatal hypoxia impairs the postnatal development of the chemoafferent pathway, as well as the ventilatory and metabolic responses to hypoxia. These alterations were mostly evident until 3 weeks after birth.