OESTRADIOL-17-BETA INCREASES PITUITARY-RESPONSIVENESS BY A MECHANISM THAT INVOLVES THE RELEASE AND THE PRIMING EFFECT OF LUTEINIZING-HORMONE RELEASING-FACTOR

Abstract

We have investigated the mechanism by which oestradiol-17 beta augments pituitary responsiveness to luteinizing hormone releasing factor (LH-RF). Adult rats were ovariectomized on the morning of dioestrus and implanted with either an empty silicone elastomer capsule or a capsule containing oestradiol-17 beta. Twelve hours later the LH response, tested by injecting 50 ng LH-RF/100 g i.v., was significantly greater in animals implanted with an oestradiol capsule compared with that in animals implanted with an empty capsule. The effect of oestradiol was blocked by sodium pentobarbitone administered 4 h before the test, and this block was overcome by infusing LH-RF during the 4 h period at doses..