Vitamin E (Trolox) addition to Tris-egg yolk extender preserves ram spermatozoon structure and kinematics after cryopreservation

a b s t r a c t Several studies reveal that vitamin E acts as a cellular stabilizer of unsaturated lipids against oxidative deterioration, thus maintaining structural and functional integrity at the subcell- ular level. The objective of this study was to evaluate Vitamin E (Trolox) addition to freezing extender for ram spermatozoa. Semen samples were diluted in Tris-yolk egg medium with- out antioxidant (control group) and with Trolox in different concentrations (30, 60 and 120 M). After thawing (37 ◦ C/30 s), samples were subjected to analysis for plasma mem- brane integrity (PMi), acrosome integrity (Aci), mitochondrial membrane potential (MMP), sperm kinematics, and ultrastructural integrity. The Trolox 60 and 120 M groups showed higher percentages of iPMs (P < 0.05) when compared to the control group. Differences were observed among groups in sperm kinematic indicators (progressive motility, linear- ity, straightness, oscillation index, straight-line velocity and average path velocity), with higher values (P < 0.05) for the Trolox 60 and 120 M groups. On ultrastructural assessment, Trolox addition at the three concentrations preserved spermatozoon head plasma mem- branes, while for the spermatozoon tail, plasma membrane preservation at 60 M was higher (P < 0.05) than the other groups. The Trolox 60 and 120 M groups presented more mitochondrial ultrastructural preservation than the other groups (P < 0.05). These results indicate that Trolox addition to Tris-egg yolk at 60 and 120 M provides greater structural integrity (plasma membrane and mitochondria) and kinematics for ram spermatozoa after cryopreservation.