EPICATECHIN IMPROVES FROZEN SPERM VITALITY BY ITS ANTIOXIDANT AND CRYOPROTECTIVE ACTIONS

Abstract

This study served to elucidate the effects of three selected doses of epicatechin (EPI; 25, 50 or 100 μmol/L) on the motion and oxidative profile of bovine spermatozoa subjected to the process of cryopreservation. Furthermore, we focused on the impact of EPI on the expression patterns of heat shock proteins 90 and 70 as well as the BAX and Bcl-2 proteins involved in the process of apoptosis. The experimental samples were compared with a native control as well as specimens cryopreserved in the absence of any supplement. Our dada indicates that particularly 50 and 100 μmol/L EPI assured a higher preservation of the sperm motility (p<0.001) in comparison with the cryopreserved control. The best protection of the sperm DNA (p<0.05), lipids (p<0.05) and proteins (p<0.01) were observed in the samples exposed to 100 μmol/L EPI in comparison to untreated frozen samples. The presence of higher EPI concentrations in the cryopreservation medium led to significant stabilization of the heat shock protein 90 (p<0.01 in case of 50 μmol/L EPI; p<0.001 with respect to 100 μmol/L EPI) as well as a higher maintenance of the BAX:Bcl-2 ratio (p<0.001) when compared to the untreated frozen control. In summary, we may assume that EPI exhibits antioxidant properties which enable the molecule to prevent excessive damage to biomolecules essential for the cell survival and offer an additional layer of protection to spermatozoa exposed to low temperatures, all of which may be translated into a higher post-thaw sperm motility and activity.