Central control of steroid hormone secretion

Peripheral plasma levels of cortisol and androstenedione exhibit closely related patterns of change which reflect the episodic secretion of these steroids and their dependence upon corticotrophin. The diurnal pattern appears to be reproducible from day to day within an individual, implying the existence of some type of programmed C.N.S. activity. Although plasma aldosterone levels show changes which also relate closely to those described by cortisol, it appears that it is renin, not corticotrophin, which mediates these changes and thus ACTH and renin release appear to be linked in some way. Stimulation of adrenocortical activity with synthetic corticotrophin, or infusion of androstenedione, illustrates the rapid conversion of this steroid to oestrone. The pattern of peripheral steroid levels observed suggests that the clearance of androstenedione must alter rapidly, and confirms the importance of the adrenal cortex as an indirect source of oestrogen.