PARENT SESSION
Capacitation & Acrosome Reaction

EFFECT OF PROGESTERONE ON BOVINE SPERM CAPACITATION AND ACROSOME REACTION.

Thérien, Isabelle¹, Manjunath, Puttaswamy¹, ¹

ABSTRACT- Progesterone appears to stimulate in vivo sperm capacitation and/or induce the acrosome reaction (AR) in some species (human, hamster, stallion). In bovine, it is now well established that the BSP-A1/-A2 proteins (the major proteins of bovine seminal plasma) promote sperm capacitation. In this study, we investigated the effect of progesterone on bovine sperm capacitation and the AR. Washed bovine epididymal sperm were incubated (0-6 h) with different concentrations of progesterone (0.01-10 g/ml) in the presence or in the absence of BSP-A1/-A2 proteins (40 g/ml, capacitating conditions). At different time interval, aliquot of sperm were taken and were incubated with or without lysophosphatidylcholine (lyso-PC) which induce the AR in capacitated sperm. BSP-A1/-A2 proteins alone stimulated the AR induced by lyso-PC (17.8 ± 1.1% compared to control, medium alone, 10.6 ± 1.5%) but did not stimulate the AR when lyso-PC was omitted (8.8 ± 0.1% compared to control, 8.2 ± 0.8 %). Progesterone alone did not stimulate the AR with or without lyso-PC (10.9-12.1% and 7.9-9.7%, respectively). However, when sperm were incubated in capacitating conditions (in the presence of BSP-A1/-A2), the presence of progesterone (0.01 g/ml) in the medium increased the number of acrosome reacted sperm and no significant differences were observed between the percentage of AR obtained in the presence or in the absence of lyso-PC (17.9-20.9% with lyso-PC vs 15.3-18.9% without lyso-PC). Furthermore, the presence of progesterone in the media did not affect the membrane cholesterol efflux potential of the BSP-A1/-A2 proteins. These results demonstrate a potential role of progesterone in bovine sperm AR but not in capacitation.

KEY WORDS: progesterone, acrosome reaction, capacitation, bovine