Expression of progesterone membrane receptor in spermatozoa from normozoospermic and oligozoospermic men

The aim of the study was to assess the expression of progesterone membrane receptors in human spermatozoa before and after capacitation. The sperm of 16 men with normozoospermia and 48 men with oligozoospermia was examined. Progesterone-BSA complex labelled with fluorescein isothiocyanate (P-BSA-FITC) was applied to visualise the progesterone receptors. The spermatozoa were capacitated with BM1 medium. In freshly ejaculated sperm from normozoospermic men, P-BSA-FITC staining (bright fluorescence of acrosome region) was observed in 50.1+/-5.1% of spermatozoa. Following capacitation in BM1 medium, the percentage of P-BSA-FITC stained spermatozoa increased to 69.9+/-3.3%. In sperm from slight oligozoospermia the percentage of P-BSA-FITC stained cells before and after capacitation was 48.2+/-8.5% and 67.9+/-4.2%, respectively. In men with severe oligozoospermia the percentage of P-BSA-FITC stained cells was 11.9+/-1.7% and 11.9+/-1.9%, respectively. It is supposed that progesterone membrane receptors in human spermatozoa are gradually exposed during capacitation. Disturbances in the expression of progesterone membrane receptors might be involved in male infertility.