Effect of Sex Steroids on β-Endorphin in Hypophyseal Portal Blood*

Abstract
Previous studies in female monkeys have shownthat β-endorphin (β-EP) of hypothalamic origin is present inhigh concentrations in the hypophyseal portal blood and declinesat the time of menses and after ovariectomy. In this study wehave examined the effects of estradiol and progesterone replacementon portal blood β-EP in ovariectomized monkeys. After acute iv administration of estradiol (2 jug), β-EP did not rise frompreviously low levels (J Clin Endocrinol Metab55: 877, 1982)