Prolactin Secretion in vitro

Abstract

Summary

Effects of estradiol (E), progesterone (P), testosterone (T), cortisol (F) and corticosterone (B) on prolactin production by rat adenohypophysis in vitro were examined. Addition of P (1 and 2 μg/ml), T (1 and 2 μg/ml), B (1 and 20 μg/ml) or F (0.5 and 5.0 μg/ml to culture medium did not influence prolactin secretion; however, F at 10 μg/ml significantly depressed prolactin production in vitro. This depressant effect of F, however, cannot be regarded as physiological due to the high concentration used. Incorporation of E into medium at concentrations of 0.05 and 0.5 μg/ml significantly increased prolactin secretion whereas E at 2.0 μg/ml was without effect. These observations indicate that only E, of all steroids tested, can act at the pituitary level to influence prolactin secretion. The effects of other steroid hormones on prolactin secretion in vivo are probably mediated via pathways other than by a direct effect on the adenohypophy-sis.

We are indebted to Roger Deuben for technical assistance.