Rosmarinic acid improves function and in vitro fertilising ability of boar sperm after cryopreservation

Abstract

During cryopreservation, oxidative stress exerts physical and chemical changes on sperm functionality. In the present study we investigated the antioxidant effect of rosmarinic acid (RA) on quality and fertilising ability of frozen–thawed boar spermatozoa. Ejaculates collected from mature boar were cryopreserved in lactose–egg yolk buffer supplemented with different concentrations of RA (0μM, 26.25μM, 52.5μM and 105μM). Motion parameters, acrosome and plasma membrane integrity, lipoperoxidation levels, DNA oxidative damage (8-hydroxy-2-deoxyguanosine base lesion) and in vitro fertilisation ability were evaluated. Total and progressive motility were significantly higher in experimental extenders with RA than in the control (P<0.05) at 0 and 120min post-thawing. The plasma and acrosomal membrane integrity were improved by supplementation with 105μMRA (P<0.05). Negative correlation between RA and malondialdehyde (MDA) concentration were determined (P<0.05). After thawing, the percentage of spermatozoa with oxidised DNA did not differ between extenders, however, at 120 and 240min post-thawing, the samples supplemented with 105μMRA showed the lowest DNA oxidation rate (P<0.05). The penetration rate was significantly higher on spermatozoa cryopreserved with 105μMRA (P<0.05). The results suggest that RA provides a protection for boar spermatozoa against oxidative stress during cryopreservation by their antioxidant properties.