PERINATAL ASPHYXIA-INDUCED CHANGES IN RAT-BRAIN TYROSINE HYDROXYLASE-IMMUNOREACTIVE CELL BODY NUMBER - EFFECTS OF NICOTINE TREATMENT

Perinatal asphyxia (15-22 min) was induced to male Sprague-Dawley rat pups during the last day of gestation and the surviving pups were sacr ificed at 4 weeks of age. Brain sections were stained for tyrosine hyd roxylase immunoreactivity and Cresyl violet. With increasing duration of perinatal asphyxia a reduction in the number of tyrosine hydroxylas e immunoreactive (TH-IR) nerve cell bodies was found in the locus ceru leus, probably reflecting an increased death of noradrenaline nerve ce ll bodies. In contrast, perinatal asphyxia (15-20 min) resulted in an increased number of TH-IR nerve cell bodies in the A9 (zona compacta o f the substantia nigra) and the A10 (ventral tegmental area) regions o f the mesencephalon, probably reflecting an increased survival of dopa mine nerve cell bodies. Perinatal asphyxia for longer than 20 min peri ods reduced the number of TH-IR cell bodies in the 4 week old rat, eve n below those found in control animals, indicating that when asphyxia is induced for a period leading to almost 100% mortality, a long-term reduction of the number of mesencephalic dopamine neurons is produced. It has previously been shown that a 4 week postnatal nicotine (0.2 mu mol/kg per h) treatment counteracts the asphyxia-induced increase in TH-IR cell body number in the substantia nigra and ventral tegmental a rea, Such nicotine treatment did not influence the reduction in TH-IR cell bodies in the locus ceruleus following 15-20 min of perinatal asp hyxia. (C) 1997 Elsevier Science Ireland Ltd.