ENDOTHELIN AND NEUTRAL ENDOPEPTIDASE IN THE ENDOMETRIUM OF WOMEN WITHMENORRHAGIA

The mechanisms underlying excessive menstrual bleeding or menorrhagia are not understood, In view of its potent vasoconstrictor and growth f actor properties, endothelin has been proposed to have a potential par acrine role in the regulation of uterine blood how and therefore could be a factor in menorrhagia. We compared the cellular localization of endothelin and its metabolizing enzyme, neutral endopeptidase, in endo metrial biopsies from women with documented menorrhagia and in those w ith a normal menstrual cycle, Menorrhagia was documented by measuremen t of menstrual blood loss, 146 +/- 141 ml (median +/- SD). Endothelin and neutral endopeptidase were localized by immunohistochemistry, and the staining intensity was graded. Their immunostaining patterns were found to differ in menorrhagia compared to the normal menstrual cycle. Endothelin was reduced in glandular epithelium in menorrhagia and did not vary cyclically, while neutral endopeptidase was increased in the glandular epithelium, In menorrhagia, stromal endothelin immunoreacti vity was not different from the normal cycle and although neutral endo peptidase immunostaining in stroma was similar to the secretory phase of normal endometrium, cyclical variation was absent. The potential fo r increased metabolism of endothelin could be an explanation for the d ecreased endothelin immunostaining in the glandular epithelium.