Ontogenesis of alpha 2- and beta-adrenoreceptors in brain cortex of rats after corticosterone injections to their mothers on days 16 and 18 days of gestation was studied using 3H-clonidine and 3H-dihydroaoprenolol binding. After corticosterone treatment the level of beta-adrenoreceptors was decreased on day 7 but increased on day 16 after birth; On the contrary, catecholamine levels and biosynthesis determined previously were increased in the first and decreased in the second age group. beta-adrenoreceptors' density and noradrenaline level during other periods of pre- and postnatal development remained unchanged. Corticosterone treatment inhibited the increase of alpha 2-adrenoreceptor density during ontogenesis. The decrease of the alpha 2-adrenoreceptors was most significant in 35- and 70-day old rates. The hormone had no effect on the adrenoreceptors' affinity to ligands. Injections of the solvent to the pregnant females which is weak stressor increasing corticosteroids levels in the blood, had a similar but less prominent effect on the ontogenesis of adrenoreceptors in the offspring brain. Thus, the effect of corticosterone on the ontogenesis of the beta-adrenoreceptors is probably associated with changes of the neurotransmitter level, and its effect on alpha 2-adrenoreceptors involves some unknown specific hormone-dependent regulator.
Animals Cerebral Cortex