Immunolocalization of endothelin and neutral endopeptidase in the endometrium of users of subdermally implanted levonorgestrel (Norplant®)

• Published in: Human reproduction (Oxford) 1995-10, Vol.10 (10), p.2584-2589
• Main Authors: Marsh, M.M., Butt, A.R., Riley, S.C., Rogers, P.A.W., Susil, B., Affandi, B., Findlay, J.K., Salamonsen, L.A.
• Format: Article
• Language: English
• Subjects: Atrophy; Biological and medical sciences; Biopsy; Birth control; Contraceptives, Oral, Synthetic - adverse effects; Drug Implants; endometrial bleeding; Endometrium - drug effects; Endometrium - metabolism; Endometrium - pathology; endothelin; Endothelins - analysis; Endothelins - metabolism; Estradiol - blood; Female; Gynecology. Andrology. Obstetrics; Hormonal contraception; Humans; Immunohistochemistry; Indonesia; Levonorgestrel - adverse effects; Medical sciences; neutral endopeptidase; Norplant; Progesterone - blood; slow-release levonorgestrel; Time Factors; Uterine Hemorrhage - chemically induced
• ISSN: 0268-1161; 1460-2350
• DOI: 10.1093/oxfordjournals.humrep.a135750

Subdermally implanted slow-release levonorgestrel (Norplant®), a widely used effective contraceptive, has a high rate of discontinuation due to unacceptable menstrual bleeding disturbances. Endothelin (ET), a potent vasoconstrictor,varies across the menstrual cycle in normal endometrium.It has been proposed that ET has a potential paracrine role in the regulation of uterine blood flow.Neutral endopeptidase (NEP), a membrane-bound ectoenzyme,can inactivate ET and is localized principally in endometrial stroma. We have compared the immunolocalization of ET and NEP in endometrial biopsies from Indonesian women using Norplant® with normal controls.Differences were observed in the glandular and luminal epithelium of Norplant®-treated subjects, where ET immunostaining was low while NEP immunoreactivity was increased. The latter may represent a local increase in enzyme activity, potentially explaining the reduced ET immunoreactivity. There was no correlation of ET immunoreactivity with the duration of implant use or total number of bleeding days. The marked differences in the ET immunostaining pattern in Norplant® users, with their increased risk of abnormal uterine bleeding, suggest that ET may be important in controlling menstrual bleeding.Whether endometrial epithelial cell ET has a role as a mitogen in endometrial repair and regeneration, or as a vasoconstrictor important in the cessation of bleeding following menstruation, remains to be determined.