EARLY POSTNATAL HYPOXIA INDUCES LONG-TERM CHANGES IN THE DOPAMINERGICSYSTEM IN RATS

A rat model of a mild, chronic, early postnatal hypoxia, characterized by long-term consequences in the behavioural outcome, was used to stu dy long-term consequences in the dopaminergic system. Exposure of newb orn rats to an early postnatal hypoxia (hypobaric hypoxia, 11 kPa pO2 in the inspiratory air, 2nd-10th day of life, 10 hours daily) brings a bout the following lasting neurochemical changes: an increased stimula ted dopamine release rate from striatum slices by about 30%, an increa sed low affinity, high capacity dopamine uptake into striatum synaptos omes by about 100%. The critical period to produce an increased releas e rate of dopamine was estimated as day 2-6 postnatally. There are no long-term changes in the concentration of dopamine and its metabolites and in the tyrosine hydroxylase activity in consequences of this earl y postnatal hypoxia. Treatment of newborn animals with L-DOPA (10-50 m ug/g body weight) previous to hypoxia normalizes the DA release rate.