Combined effects of resveratrol and epigallocatechin-3-gallate on post thaw boar sperm and IVF parameters.

Frozen-thawed boar semen suffer a fertility decrease that negatively affects its widespread use. In recent years supplementing frozen-thawed boar sperm with different antioxidants gave interesting and promising results; the aim of the present work was to study the effect of supplementing boar sperm thawing medium for 1 h with combination of epigallocatechin-3-gallate (EGCG, 50 µM) and Resveratrol (R, 2 mM), on boar sperm motility (assessed by CASA), viability, acrosome integrity, mitochondrial function, lipid peroxidation and DNA integrity (assessed by flow cytometry), protein tyrosine phosphorylation (assessed by immunofluorescence) and on in vitro fertilization (IVF). Our results demonstrate that sperm motility is negatively affected by R (alone or associated with EGCG, p < 0.05) in comparison to control and EGCG groups both at 1 h and 4 h; this effect is evident both in average motility parameters and in single cells kinematics, studied by cluster analysis, that showed the presence of a specific cell population with simil-hyperactivated features in R group (p < 0.01). Viability, acrosome integrity, mitochondrial functionality and lipid peroxidation are not influenced by the addition of the antioxidants; finally, DNA integrity is negatively influenced by R (both alone or associated with EGCG) both at 1 h and 4 h incubation (p < 0.05). Finally, tyrosine phosphorylated protein immunolocalization, used as capacitation parameter, is not affected by the different treatments. Penetration rate is strongly enhanced by R, both alone or associated with EGCG (p < 0.05); EGCG increases penetration rate as well but to a lower extent. Our findings demonstrate that the combination of R and EGCG could positively affect frozen-thawed boar sperm fertility in vitro; the effect is evident also in R groups, thus demonstrating that this antioxidant is predominant, and no synergic effect is present. Some insights are needed to understand if, in particular R (that showed the strongest effect) could be profitably used for artificial insemination in vivo, given the detrimental effect of this molecule on both sperm motility and DNA integrity.

Biological effects of polyphenol-rich extract and fractions from an oenological oak-derived tannin on in vitro swine sperm capacitation and fertilizing ability.

Although excessive ROS levels induce sperm damage, sperm capacitation is an oxidative event that requires low amounts of ROS. As the antioxidant activity of the ethanol extract (TRE) of a commercial oenological tannin (Quercus robur toasted oak wood, Tan'Activ R®) and its four fractions (FA, FB, FC, FD) has been recently reported, the present study was set up to investigate the biological effects of TRE and its fractions in an in vitro model of sperm capacitation and fertilization. Boar sperm capacitation or gamete coincubation were performed in presence of TRE or its fractions (0, 1, 10, 100 µg/ml). TRE at the concentration of 10 µg/ml (TRE10) stimulated sperm capacitation, as it increased (p < .001) the percentage of spermatozoa with tyrosine-phosphorylated protein positivity in the tail principal piece (B pattern) (67.0 ±â€¯10.6 vs. 48.6 ±â€¯9.0, mean ±â€¯SD for TRE10 vs. Ctr respectively). Moreover T10 significantly (p < .001) increased oocyte fertilization rate (91.9 ±â€¯4.0 vs. 69.0 ±â€¯14.8, TRE10 vs. Ctr respectively). An opposite effect of TRE at the concentration of 100 µg/ml (TRE100) on both sperm capacitation (B pattern cell percentage 33.3 ±â€¯29.2) and fertilizing ability (fertilization rate 4.9 ±â€¯8.3), associated with a higher sperm viability (66.9 ±â€¯9.3 vs. 35.4 ±â€¯10.8, TRE100 vs. Ctr respectively) (p < .001), was recorded. The potency of the TRE fractions seems to be highest in FB followed by FC, faint in FD and nearly absent in FA. Our results show that TRE and its fractions, in a different extent, exert a powerful biological effect in finely modulating capacitation and sperm fertilizing ability.

Effects of resveratrol on vitrified porcine oocytes.

Vitrified MII porcine oocytes are characterized by reduced developmental competence, associated with the activation of the apoptotic pathway. Resveratrol (R), a polyphenolic compound present in several vegetal sources, has been reported to exert, among all its other biological effects, an antiapoptotic one. The aim of this study was to determine the effects of R (2 µM) on the apoptotic status of porcine oocytes vitrified by Cryotop method, evaluating phosphatidylserine (PS) exteriorization and caspases activation. R was added during IVM (A); 2 h postwarming incubation (B); vitrification/warming and 2 h postwarming incubation (C); all previous phases (D). Data on PS exteriorization showed, in each treated group, a significantly higher (P < 0.05) percentage of live nonapoptotic oocytes as compared with CTR; moreover, the percentage of live apoptotic oocytes was significantly (P < 0.05) lower in all R-treated groups relative to CTR. The results on caspase activation showed a tendency to an increase of viable oocytes with inactive caspases in B, C, and D, while a significant (P < 0.05) increase in A compared to CTR was recorded. These data demonstrate that R supplementation in various phases of IVM and vitrification/warming procedure can modulate the apoptotic process, improving the resistance of porcine oocytes to cryopreservation-induced damage.