The Effect of Cortisol on the Secretion of Sex Steroids from Cultured Ovarian Follicles of Rainbow Trout

In a series of experiments, the effect of cortisol on the ability of rainbow trout (Salmo gairdneri) ovarian follicles to secrete sex steroids in vitro was investigated. The basal rate of secretion of sex steroids (oestradiol and testosterone) was suppressed in a dose-dependent manner by the addition of cortisol to the incubation medium. This suppression was evident using physiological levels of cortisol (less than 100 ng ml-1). The possibility of elevated plasma cortisol levels (due to stress) reducing the reproductive ability of sexually maturing female trout through a direct effect of cortisol on the ovary is discussed.