Healthy women and patients with endometriosis show high concentrations of inhibin A, inhibin B, and activin A in peritoneal fluid throughout the menstrual cycle

Inhibin A, inhibin B, and activin A are growth factors which play local aut ocrine/paracrine roles in reproductive tissues, Since peritoneal fluid horm one content may reflect in part ovarian and endometrial secretory activitie s, the present study aimed to evaluate: (i) whether inhibin alpha-, activin beta A- and beta B-subunits, and activin receptor type II and type LIE mRN A are expressed in peritoneal tissues; (ii) expression and secretion of inh ibin A and B, and activin A in cultured endometriotic cells; and (iii) conc entrations of inhibin A and B, and activin A in serum and in peritoneal flu id in healthy women and in patients with endometriosis throughout the menst rual cycle. A group of women (n = 72) was recruited at laparoscopy for infe rtility investigation and divided into two groups: (i) control healthy wome n (n = 35), (ii) women with endometriosis (n = 37), Both groups were subdiv ided according to the follicular and luteal phase of the menstrual cycle, A t the time of laparoscopy, specimens of peritoneal tissues were collected f rom three healthy women, while endometriotic tissue samples were collected and cultured from three women with endometriosis. Peritoneal tissues and cu ltured endometriotic cells expressed inhibin alpha-, activin beta A-, and b eta B-subunits, and activin receptors mRNAs; in addition, inhibin-related p roteins were measurable in culture medium, In healthy women, inhibin A and B, and activin A concentrations in peritoneal fluid were significantly high er than in serum (P < 0.001), at both phases of the menstrual cycle, Perito neal inhibin A and B, and activin A concentrations were not significantly d ifferent between healthy women and patients with endometriosis, either when evaluated according to the degree of the disease and/or to the phase of th e menstrual cycle. In conclusion, the findings that high concentrations are present in peritoneal fluid and that menstrual cycle-related changes occur suggest that reproductive organs may contribute to inhibin-related protein s in peritoneal fluid.