Effects of plasmin on sperm-oocyte interactions during in vitro fertilization in the pig

초록

The present study was undertaken to examine the effect of plasmin on sperm viability and sperm-oocyte interaction during in vitro fertilization in the pig. Porcine sperm, which were washed in Dulbecco's PBS were re-suspended and incubated in fertilization medium (mTBM; modified Tris-buffered medium) containing 0, 0.1, 1.0, 10.0 or 100.0 ng/mL of plasmin. Sperm viability was not affected by plasmin treatment. Addition of plasmin in doses ranging from 0.1 to 100.0 ng/mL for 2,4 or 6 h to washed boar sperm resulted in enhancement of acrosome reaction (AR) compared with untreated cells. The concentration of 0.1 ng/mL plasmin (95 +/- 18 sperm/oocyte) had no effect on sperm binding, whereas 1.0 ng/mL (123 +/- 21 sperm/oocyte), 10.0 ng/mL (124 +/- 16 sperm/oocyte) and 100.0 ng/mL (124 +/- 15 sperm/oocyte) of plasmin increased sperm binding compared with the control (83 +/- 15 sperm/oocyte). The zona pellucida solubility (zona dissolution time) was less in medium with 1.0 ng/mL (123 +/- 24 s), 10.0 ng/mL (99 +/- 15 s) or 100.0 ng/mL (95 +/- 19 s) plasmin compared with control (176 +/- 27 s). When pig oocytes and sperm were co-incubated in various concentrations of plasmin for 6 h, the penetration rate was greater in medium with 1.0 ng/mL plasmin (77.5 +/- 3.1 %) compared with the control. However, there were no differences in the polyspermic rates and mean number of sperm (MNS)/oocyte between the groups treated with plasmin and control. These results suggest that plasmin might play a role in events related to fertilization. (c) 2006 Elsevier B.V. All rights reserved.

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