Peritoneal fluid modifies the response of human spermatozoa to follicular fluid.

The aim of this study was to elucidate the mechanism involved in the acrosome reaction (AR) induced by follicular fluid (FF) in spermatozoa previously exposed to peritoneal fluid (PF). The influence of progesterone was also investigated. Semen samples were from 18 normozoospermic donors. PF samples were from 13 women with unexplained infertility and from a woman treated with synthetic progestagen. FF samples were collected from six women undergoing IVF/embryo transfer and pooled. Motile spermatozoa were capacitated overnight and a kinetic and inhibition study on the FF-induced AR was performed. Spermatozoa pretreated with PF were challenged with either FF or progesterone. The ability of progesterone- and progestagen-supplemented PF to induce AR was analysed. Enzyme-digested PF was also tested. Pre-incubation with PF for 60 min completely prevented the FF-induced AR; spermatozoa treated with PF were unable to respond to FF or progesterone and this effect was not reversible. Progesterone- and progestagen-supplemented PF stimulated the AR relative to controls. Enzyme-digested PF did not have an inhibitory capacity. These data strongly suggest that there are one or more inhibitory proteins in PF that interact with spermatozoa so as to prevent access of progesterone to its receptor and thus inhibit the occurrence of the AR. The oviduct, or Fallopian tube, provides a place for spermatozoa and egg transport and storage, fertilization and early embryo development. If ovulation has not occurred, spermatozoa may reside in the oviduct for several hours or even a few days, awaiting oocyte arrival. It is assumed that fluids present in the female genital tract may have a role in synchronizing the timing required to guarantee the success of fertilization. We previously observed that the peritoneal fluid that bathes the peritoneal cavity is a suitable medium for sperm survival and we also reported that this fluid could stabilize spermatozoa. In this study we show further evidence that the exposure to peritoneal fluid modifies the response of spermatozoa to oocyte signals.

Comparative concentrations of steroid hormones and proteins in human peri-ovulatory peritoneal and follicular fluids.

Despite the fact that both peritoneal (PF) and follicular (FF) fluids have a common ovarian origin, FF is a natural inducer of sperm acrosome reaction (AR) while PF is not. To better understand these effects, concentrations of oestradiol, progesterone and proteins in peri-ovulatory PF and FF were determined and compared. PF was aspirated by laparoscopy at the peri-ovulatory stage from women with unexplained infertility. FF was collected from patients undergoing IVF and pooled. PF and FF were tested for the presence of antisperm antibodies. Oestradiol and progesterone were measured by enzyme immunoassay, and total protein concentration was determined and analysed. The AR was determined in spermatozoa that were exposed to PF alone, progesterone-supplemented PF, progesterone, control medium, or ethanol. No antisperm antibodies were found in any fluid tested. Oestradiol and progesterone and concentrations in PF were significantly lower than in FF. Protein concentration was also significantly lower in PF than in FF, but no differences were observed between the electrophoretic patterns. When capacitated spermatozoa were exposed to progesterone-supplemented PF there was a significant increase in the percentage of AR with respect to those in PF, control medium or ethanol. These results suggest that the lack of AR-stimulating activity of PF was related to its lower progesterone concentration compared with FF.

Modulation of human sperm function by peritoneal fluid.

OBJECTIVE: To examine the effect of peritoneal fluid on various parameters of sperm function in vitro. DESIGN: Prospective study. SETTING: Basic research laboratory. PATIENT(S): Semen samples were obtained from normozoospermic volunteers (n = 43). Peritoneal fluids were aspirated laparoscopically from women with unexplained infertility (n = 14). Follicular fluid and oocytes were collected from patients undergoing IVF-ET. INTERVENTION(S): Sperm incubated under capacitating conditions were exposed to peritoneal fluid, and functional variables were evaluated in vitro. MAIN OUTCOME MEASURE(S): Sperm viability and motility, follicular fluid and calcium ionophore-induced acrosome reactions, protein tyrosine phosphorylation, expression of D-mannose binding sites, and ability of sperm to interact with zona pellucida. RESULT(S): Exposure of sperm to peritoneal fluid for up to 6 hours did not affect sperm viability or motility. Unlike follicular fluid, peritoneal fluid did not induce the acrosome reaction. Moreover, incubation of sperm with > or =20% v/v peritoneal fluid for 1 hour prevented the follicular fluid and the ionophore-induced acrosome reaction. Although treatment with peritoneal fluid allowed protein tyrosine phosphorylation during capacitation, it resulted in a significant decrease in the expression of D-mannose binding sites and sperm-zona pellucida binding. CONCLUSION(S): Peritoneal fluid maintains sperm survival and decreases sperm ability to respond to inducers of the acrosome reaction and bind to the zona pellucida in vitro, indicating that this fluid might modulate sperm function in vivo.