| Cryopreservation is the most practical approach for long-term storage of sperm in boars,providing for more efficient breeding,and promoting the rapid growth of swine models.encourage international exchange,boar sperm cryopreservation would enhance herd productivity,help control transmission of certain pathogens,facilitate gender selection technology.But,cryopreservation boar sperm is not as efficient as liquid-preserved semen due to the high susceptibility of boar sperm to damage during cryopreservation and thawing.The reduced fertilizing ability of boar sperm after freezing and thawing is well recognized.In which the oxidative damage is considered as one of the main factor.The oxidative damage is mainly induced by the increase of reactive oxygen species(ROS)levels in sperm.The reason for the susceptibility of boar sperm to ROS is because that the relatively high concentration of unsaturated fatty acids among the membrane lipids and comparatively low innate antioxidative capacity of boar seminal plasma.In particular,the superoxide radicals which are generated during the procedure of cryopreservation and thawing will result in lipid peroxidation of spermatozoa membrane,a decrease in integrity of membrane and an increase of apoptosis of spermatozoa so that sperm viability and motility are affected.In order to ameliorate the oxidative damage,one approach is to use antioxidant during freeze-thawing.Astragalus polysaccharides(APS),a main component of astragalus mongholicus(AM),has been applied extensively on alleviating immune stress and viral infections.evidence indicates that APS can help to clean up superoxide radicals and intervene in the lipid peroxidation.It has been proved that APS can enhance antioxidative effect and reduce membrane damage caused by free radical and lipid peroxide.However,AM shows a significant stimulatory effect on the motility and mitochondrial activity of human sperm in vitro.On these bases,the aim of the present study was to assess whether APS supplementation in thawing boar sperm extender could enhance antioxidant ability,improve sperm fertilizing capacity during in vitro fertilization(IVF),and further enhance embryo development.we found that the Astragalus polysaccharides(APS)addition to thawed boar sperm can enhance the antioxidant ability of sperm and finally improve in vitro fertilization(IVF)and embryo development outcome.The addition of 0.5 mg/mL APS to thawed sperm did not induce any significant effect on sperm viability or motility as compared to sperm without APS treatment.However,thawed sperm with addition of 0.5 mg/mL APS showed improved mitochondrial activity,higher penetration rate and increased total IVF efficiency compared with control group.Moreover,our results indicate that the supplementation of APS in thawed sperm decreased the reactive oxygen species(ROS)concentration and meanwhile improved the activity of superoxide dismutase(SOD)and catalase(CAT).Finally,the addition of APS significantly increased the cleavage rate and blastocyst rate compared to control group.the APS could improve the IVF and early embryonic development process probably thanks to its antioxidant activity.Thus,these results imply that APS has practical potential to enhance boar sperm reproductive performance. |
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