Capacitation status of activated bovine sperm cultured in media containing methyl-β-cyclodextrin affects the acrosome reaction and fertility

Mammalian sperm undergo a series of biochemical transformations in the female reproductive tract that are collectively known as capacitation. One of the key processes involved in capacitation is the activation of sperm motility. Here, we investigated the capacitation and fertility status of activated sperm which had been cultured in media containing methyl-beta-cyclodextrin (MBCD). In order to do this, single activated sperm were caught using a micropipette and stained with chlortetracycline (CTC). Firstly, we investigated the effects of preincubation upon motility, capacitation of activated sperm and fertility. Culture in preincubation media supplemented with MBCD increased the rates of activation and fertilization compared with sperm cultured by control methods (p < 0.05). Following capture, individual activated sperm mostly exhibited a pattern characteristic of capacitation. Secondly we examined the effects of culturing sperm in media with or without glucose (G) and pyruvate acid (P) upon activated motility, the capacitation of activated sperm and fertility. Supplementation of culture media with G and P resulted in higher proportions of activated sperm and increased fertilization rates compared to culture without G and P (p < 0.05). Most of the sperm activated by culture in G and P exhibited patterns characteristic of capacitation. Without G and P, individual activated sperm mostly exhibited patterns characteristic of the acrosome reaction (p < 0.05). In conclusion, activated sperm exhibited patterns characteristic of capacitation. In addition, sperm activated in media containing an energy source (glucose and pyruvate acid) appeared to exhibit acrosome reactiveness and fertility.