Effect of osteopontin on buffalo sperm capacitation.

The aim of this study was to evaluate the effect of osteopontin (OPN) to induce capacitation of buffalo spermatozoa in vitro. Capacitation was assessed by the ability of sperm to undergo the acrosome reaction (AR) after incubation with lysophosphatidylcholine (LPC), a known inducer of AR only on capacitated spermatozoa. Buffalo frozen-thawed spermatozoa were incubated for 2 and 4 h in TALP medium (control) or in TALP medium supplemented with 0.01 mM heparin, or with 0.1, 1, 10 µg/mL OPN. Two-hours incubation with 1 or 10 µg/mL OPN significantly increased (P<0.05) the percentage of AR compared to the control group whereas heparin and 0.1µg/mL OPN provided intermediate results. After 4 hours incubation the same higher concentrations tested caused a further increase (P <0.01) compared with the control. Furthermore, after 4 hours the treatment with heparin enhanced capacitation compared with the control, as indicated by higher percentages of spermatozoa with AR (P