Involvement of progesterone and estrogen receptors in the ram sperm acrosome reaction

Abstract The steroid hormones 17-β estradiol (E2) and progesterone (P4) can regulate capacitation, hyperactive motility and the acrosome reaction (AR) during the sperm transit through the female tract. Moreover, exogenous P4 and E2 can induce the AR in ovine spermatozoa and progesterone (PR) and estrogen receptors (ERα and ERβ) are present in these cells. Thus, in order to investigate whether the effects both steroid hormones in ram sperm capacitation and AR are receptor-mediated, we incubated them with receptor agonists (tanaproget 1 μM and 5 μM for PR, or resveratrol 5 μM and 10 μM for ER) or antagonists (mifepristone 4 μM and 40 μM for PR or tamoxifen 5 μM and 10 μM for ER) in capacitating conditions. The addition of receptor modulators did not affect sperm viability or total motility, although changes in progressive motility were detected. The incubation with both receptor agonists increased the percentage of acrosome reacted spermatozoa, evaluated by chlortetracycline staining, when compared with the capacitated non-treated sample (Cap-C, P