Enhanced secretion of oxytocin from bovine granulosa cells treated with adrenal steroids

Bovine granulosa cells were exposed in vitro to various adrenal steroids (cortisol, cortisone, corticosterone, aldosterone; 1 mumol/l), in the presence and absence of stimulation by ascorbic acid (0.5 mmol/l), to determine the possible effects of these hormones on ovarian oxytocin and progesterone secretion. Only cortisol produced a consistent stimulation of the cells; the response was dose-related over the range 0.01 to 1.0 mumol/l and was greatly enhanced in the presence of ascorbate. The secretion of oxytocin was stimulated to a greater extent and with more consistency than was that of progesterone. Although the secretion of oxytocin could be stimulated by cortisol on the day of treatment, the cells also showed a delayed and persistent response to exposure earlier in the culture. It is concluded that cortisol may directly stimulate the secretion of ovarian oxytocin in the cow and that granulosa cells may respond in such a way as to smooth out the effects of short-term fluctuations in cortisol concentration.