Neutral endopeptidase is expressed on the follicular granulosa cells of rabbit ovaries

Neutral endopeptidase (NEP) is a zinc metallopeptidase ubiquitously distrib uted in various tissues in mammals. This peptidase is involved in the post- secretory metabolism of various neuropeptides and peptide hormones in vivo, such as enkephalins, bradykinin, atrial natriuretic peptide, substance P a nd endothelins. In this paper we show that NEP is expressed in ovaries as a 110-kDa glycosylated integral membrane protein with enzymatic properties s imilar to those of the kidney protein. Using immunohistochemistry, we local ize the peptidase in the granulosa cells of follicles at all stages of matu ration, with the exception of atretic follicles. We also observe immunoreac tive staining in the epithelia that lines the blood vessels in the medulla and the surface of the ovary. The co-localization of NEP and bioactive pept ides known to be physiological substrates of NEP in other tissues suggests an important role for this protein in processes such as follicle maturation , ovulation, and/or regulation of ovarian blood flow, by modulating the phy siological function of these peptides. (C) 2001 Elsevier Science Inc. All r ights reserved.