The water permeability channels aquaporins 1-4 are differentially expressed in granulosa and theca cells of the preovulatory follicle during precise stages of human ovulation

Abstract

Context: Changes in vascular permeability and expansion of the fluid-filled antrum are major events in the LH-induced ovulatory process. Objectives: Our objective was to investigate the presence and expression levels of aquaporins (AQPs) in the granulosaandtheca cellcompartmentsof the follicle during defined phases ofhuman ovulation. Design and Setting: We conducted a prospective experimental study at the Department of Obstetrics and Gynaecology at a university hospital. Participants: Twenty-eight women underwent laparoscopic sterilization and at the same time follicle retrieval at four periovulatory phases. MainOutcomeMeasures:mRNAlevels ofAQP1-4weremeasured in separated granulosaandtheca cells from preovulatory phase, early ovulatory (EO) phase, late ovulatory phase, and postovulatory phase. Immunohistochemistry was done for AQP1-4 in intact human follicles. Results: All four AQPs were expressed in both the theca and granulosa cells during ovulation. In granulosa cells, AQP1 levels increased in the late ovulatory and postovulatory phases. Expression of AQP2-3 followed a similar pattern with a marked increase in the EO phase, whereas AQP4 levels decreased from preovulatory to the EO phase. The presence of AQP1-4 in the human follicle was verified by immunohistochemistry. Conclusions: The results show for the first time the presence of AQP1-4 in human follicles during ovulation. The marked early rise in expression ofAQP2andAQP3suggests a role during the process leading to follicular rupture, and the late rise of AQP1 suggests a role in corpus luteum formation. Copyright © 2011 by The Endocrine Society.