Effect of Methyl-.BETA.-Cyclodextrin and Fertilization Promoting Peptide on Capacitation of Boar Spermatozoa in a Protein-Free Medium.

Abstract

The present study was undertaken to examine the effect of methyl-β-cyclodextrin (MBCD) and fertilization promoting peptide (FPP; pGlu-Glu-ProNH2) on the capacitation and acrosome reaction of boar spermatozoa in a protein-free medium. After washing with a protein-free medium, ejaculated spermatozoa (resuspended at 1 × 106 cells/ml) were cultured in 2 ml of modified Medium-199 containing polyvinylalcohol (mM199-PVA) supplemented or not supplemented with MBCD and/or FPP for 2 h in an atmosphere of 5% CO2 in air at 39 C. Effects of MBCD and FPP on boar spermatozoa were determined by chlortetracycline fluorescence assessment. When spermatozoa were cultured in various MBCD concentrations, capacitation was induced in a concentration-dependent manner, but spontaneous acrosome reaction was not affected. When the effect of FPP in mM199-PVA was determined, sperm capacitation was induced and spontaneous acrosome reaction was inhibited in 100 nM FPP, regardless of the absence or presence of BSA. In the last experiment, spermatozoa were cultured in mM199-PVA supplemented with various concentrations of MBCD and/or FPP. An accelerative effect of MBCD on sperm capacitation was observed in a concentration-dependent manner even in the presence of FPP, whereas 1-2 mM of MBCD neutralized the stimulatory effect of FPP on capacitation. Furthermore, FPP inhibited spontaneous acrosome reaction even in the presence of MBCD. These results demonstrate that MBCD and PFF can induce capacitation of boar spermatozoa in a protein-free medium and that FPP alone also inhibits spontaneous acrosome reaction.