Patterns of serum cortisol levels in ovariectomized females with and without androgen administration

Serum cortisol levels in humans and primates display a circadian rhythm. A study in monkeys showed that orchiectomy abolishes this circadian rhythm. The present study compared the patterns of serum cortisol levels between 9 a. m. and 3 p. m. in two groups of ovariectomized females, one treated with testosterone (T) and one without sex steroid administration. Over the first 80 minutes of the sampling period cortisol levels declined similarly in both groups, probably due to waning of stress of the experiment. Thereafter, levels fell further in the T-administered group, but not in the group without sex steroid administration. From this pilot study it is tentatively concluded that ovariectomy, in analogy with orchiectomy in monkeys, produces a loss of a circadian pattern of cortisol levels, which is reversed by administration of T. Furthermore, upon comparison of mean serum cortisol levels in the two groups, T appeared to have a suppressive effect on values of serum cortisol levels.