The+Effect+of+Hydrostatic+Pressure+Treatment+on+the+Levels+of+HSP90+and+HSP70+in+Boar+Spermatozoa+before+and+after+Freezing

Abstract

A sublethal high hydrostatic pressure (HHP) shock was reported to significantly improve the motility and viability parameters of frozen bull and boar spermatozoa, supposedly due to the sublethal stress-induced transcriptional/post-transcriptional induction of stress proteins. However, the mechanism of cryoprotection effect of HHP treatment on sperm motility remains unclear. We have previously found that the decrease of HSP90 might be associated with a decline in sperm motility during cooling of boar spermatozoa. The purpose of this study was to evaluate the effect of HHP on the levels of HSP90 and HSP70 of boar spermatozoa before and after freezing. Semen were treated or not treated with 300 or 400 bar before the start of frozen semen preparation. Samples were collected at room temperature, 15℃, 5℃ and after thawing for protein analysis. The levels of HSP70 and HSP90 were analyzed by Western blotting and densitometry. The result of qualitative and quantitative protein analysis showed that the protein profile and the level of HSP70 and HSP90 in the HHP treated group were not differed with those in the control group (P＞0.05). The level of HSP90 was significantly decreased after the semen was cooling to 5℃ (P＜0.05). The results of this study suggested that HHP treatment did not affect the levels of HSP70 and HSP90 in porcine sperm. Thus HSP70 and HSP90 may not directly involve in the HHP induced cryoprotection of porcine spermatozoa. Further study for clarifying the possible mechanism of cryoprotective effect of HHP on porcine sperm is warranted.