Detection of progesterone receptors in human spermatozoa and their correlation with morphological and functional properties

In previous reports, it has been demonstrated that progesterone (P) stimula tes capacitation, hyperactivation of human sperm motility and initiates the acrosome reaction (AR). This last effect has been related to the presence of non-genomic receptors for the steroid, localized on the sperm head plasm a membrane. These receptors can be detected after treating spermatozoa with the non-permeable conjugate Progesterone - 3-(O-carboxymethyl) oxime: bovi ne serum albumin-fluorescein isothiocyanate (P-BSA-FITC). In the present st udy, the presence of progesterone receptors was determined in a selected sp erm population with normal morphology and high progressive motility. In add ition, other parameters such as the AR, hypo-osmotic swelling test, stabili ty of chromatin and capacitating effect of P were evaluated. The percentage of P-BSA-FITC positive-spermatozoa present in the selected sperm populatio n was higher than in total seminal spermatozoa. Furthermore, spermatozoa in cubated with P showed a higher percentage motility and AR than did control spermatozoa. The HOS test indicated that membrane integrity of P-treated sp ermatozoa was not different to that found in the control sperm suspensions. Unexpectedly, the total sperm population treated with P showed a marked su sceptibility to nuclear decondensation with reducing agents. According to t hese results, the selected sperm population of this study, able to respond to P, may be similar to that with good motility and normal morphology selec ted in the female reproductive tract, before fertilization.