[Characteristics of the relationship between the circadian rhythm of the concentrations of corticosteroids and their precursors in the blood of baboon hamadryas and the initial functional state of the pituitary-adrenal cortex system].

The occurrence of a single-phase circadian rhythm in the content of cortisole, 11-deoxycortisole, 17-hydroxypregnenolone, 17-hydroxyprogesterone, pregnenolone and progesterone in the blood plasma of hamadryas baboons was established by radioimmunoassay with peak levels early in the morning and minimum ones in the evening. The time course of changes in aldosterone levels in the intact animals significantly differs from that in the adapted ones. The maintenance of animals under other ecological conditions results in the decreased levels of all steroids studied and in significant changes in circadian rhythms of the content of cortisol precursors.