[Effect of prednisolone injections in early postnatal ontogeny on the circadian rhythm of corticosteroid function in adult rats].

The effect of prednisolone injections during the early postnatal ontogenesis on the diurnal rhythm of corticosteroid function and stress reactivity in adult animals has been studied in rats. The injections of prednisolone to 7--9 days old rats resulted in the subsequent disturbance of diurnal rhythmicity in the suprarenal cortex functioning: the diurnal fluctuations of the content of 11-oxycorticosteroids in the blood plasma are smoothed out; the diurnal changes in the hormonal reaction to the stress stimulation disappear. This disturbance appears to be due to changes in the central mechanisms of the control of hypophysis-suprarenal system. The reactivity of this system per se suffered no changes.