Beta-endorphin and beta-lipotrophin in human ovary.

The presence of beta-endorphin (beta-E) and beta-lipotrophin (beta-LPH) in human ovary was studied by liquid chromatography and radioimmunoassay, and by immunoperoxidase staining. The mean concentrations (+/- S.E., N=8) of beta-E and beta-LPH in follicular fluid samples collected during the late follicular phase of normal cycles were 1.9 +/- 0.4 pmol/l and 2.9 +/- 0.8 pmol/l, respectively. After hyperstimulation with clomiphene and gonadotropin for in vitro fertilization, the mean concentrations of beta-E and beta-LPH in follicular fluid did not increase significantly, being 3.2 +/- 0.6 and 4.1 +/- 1.0 pmol/l, respectively (N=13). beta-E or beta-LPH were not found in three corpora lutea analysed. Immunohistochemical staining of ovarian tissue did not reveal any beta-E immunoreactivity. Thus the origin of beta-E and beta-LPH in the follicular fluid remained unclear. In 7 women, blood samples were collected from the peripheral and ovarian veins at laparotomy. No significant concentration excess of beta-E or beta-LPH was found in the ovarian venous plasma, suggesting that human ovaries do not secrete significant amounts of beta-E or beta-LPH into the peripheral circulation. It seems that the role of endorphins in the human ovary is less significant than previously proposed for sheep, rat or mouse ovary.