[The effect of prednisolone administration in early postnatal ontogeny on the circadian activity of the hypothalamo-hypophyseal-adrenal cortical system in adult rats].

The disturbance of glucocorticoid balance in early postnatal ontogenesis (17-19 days) as a result of prednisolone administration was shown to lead to change in diurnal periodicity of the hypothalamo-hypophysial-adrenocortical system (HHAS) in adult rats. Diurnal rhythms of zona fasciculata-reticulata relative areas, the quantity of Gomori-positive neurosecretory material in the external zone of median eminence and in the posterior pituitary of these animals was undetectable. The amplitudes of plasma corticosterone rhythm and variations of cell nuclei volume in the zona fasciculata externa was decreased more than two-fold. Diurnal periodicity of nucleoli volume of Gomori-positive neurons in a hypothalamic paraventricular nucleus (PVN) as ventromedial as dorsolateral parts was attenuated and their maximum shifted to morning hours as compared to the night peak in control animals.