2-hydroxyoestradiol inhibits prolactin release from the superfused rat pituitary gland.

The effects of 2-hydroxyoestradiol (2OH-OE2), dopamine, oestradiol-17 beta and 2OH-OE2 plus dopamine on prolactin and LH release from the male rat pituitary gland were examined in vitro. 2-Hydroxyoestradiol reduced prolactin secretion by 51% at 10(-10) mol/l and by 34% at 10(-7) mol/l, while oestradiol-17 beta had no effect at these doses. Dopamine alone (5 x 10(-7) mol/l) decreased prolactin released by 58%, 2OH-OE2 plus dopamine produced a similar inhibition of 60%. No significant effect on LH release was observed throughout.