Inhibitory and augmentative effects of oestradiol on LH-RH-induced release of LH by anterior pituitary glands from intact female rats in vitro.

Anterior pituitary glands from intact dioestrous female rats were incubated in vitro and the LH released into the medium was measured at hourly intervals. The effect of a supramaximally active dose of LH-RH was first inhibited and later augmented by oestradiol added to the medium. The augmented response also occurred when LH-RH was absent during the preceding phase of the incubation. Both effects of oestradiol could be blocked by cycloheximide, which agent, however, also partly inhibited the response to LH-RH.