Metabolism of renin-angiotensin and enkephalin in human follicular fluid: An experimental study

Background: The relationship between the biochemical characteristics of follicular fluid (FF), oocyte quality and embryonic development has not yet been elucidated. We compared samples of FF with a normal metabolic profile against samples with metabolic abnormalities to identify potential predictive biomarkers of reproductive success. Objective: To analyze peptide activity in the FF of women undergoing in vitro fertilization using 3 samples of FF per individual. Materials and Methods: FF samples were obtained by ovum pick-up. Pathological samples were defined as samples of FF obtained from women with a gynecological condition or with infertility. A total of 30 women participated in this study. 3 samples of FF were obtained per individual (90 samples), but 8 samples were excluded because they were hemolyzed. The samples (n = 82 FF) included controls (n = 36, donors without fertility problems), women with endometriosis (n = 15), unexplained infertility (n = 19), and aged 39 (n = 12). We assessed local encephalinergics: aminopeptidase-N (puromycin sensitive aminopeptidase and neutral endopeptidase; and components of the angiotensin system of the reproductive tract: prolyl-endopeptidase, APN, aspartate-aminopeptidase, and basic-aminopeptidase. Results: No differences were observed in peptide metabolism based on the presence or absence of oocytes in the FF. Women with endometriosis and aged 39 yr showed alterations in puromycin sensitive aminopeptidase (p = 0.01), aminopeptidase- B (p = 0.01), aspartate-aminopeptidase (p 0.001) and neutral endopeptidase (p 0.001). Conclusion: This study reveals alterations in the metabolism of enkephalin and angiotensin in pathological FF, which points to these components as potential diagnostic biomarkers.