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

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 subcellular 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 without antioxidant (control group) and with Trolox in different concentrations (30, 60 and 120µM). After thawing (37°C/30s), samples were subjected to analysis for plasma membrane integrity (PMi), acrosome integrity (Aci), mitochondrial membrane potential (MMP), sperm kinematics, and ultrastructural integrity. The Trolox 60 and 120µM 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, linearity, straightness, oscillation index, straight-line velocity and average path velocity), with higher values (P<0.05) for the Trolox 60 and 120µM groups. On ultrastructural assessment, Trolox addition at the three concentrations preserved spermatozoon head plasma membranes, while for the spermatozoon tail, plasma membrane preservation at 60µM was higher (P<0.05) than the other groups. The Trolox 60 and 120µM 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 120µM provides greater structural integrity (plasma membrane and mitochondria) and kinematics for ram spermatozoa after cryopreservation.

Espermatozoides caprinos criopreservados em meio à base de leite desnatado acrescido de glutationa reduzida / Goat spermatozoa after freezing in skimmed-milk extender supplemented with reduced glutathione

Visando avaliar o efeito da adição de glutationa reduzida (GSH) ao diluente de congelação de sêmen caprino à base de leite desnatado, utilizou-se sêmen de cinco reprodutores Boer. Após colheita e avaliação, procedeu-se à formação do pool dos ejaculados e diluição em leite desnatado e glicerol 7 por cento, acrescido de antioxidantes: G1) Controle; G2) GSH 2mM mL-1; G3) GSH 5mM mL-1 e G4) GSH 7mM mL-1. As amostras foram congeladas em palhetas (0,25mL) e armazenadas a -196°C. Após descongelação, avaliou-se a integridade de membrana plasmática (iMP) e acrossomal (iAc), potencial de membrana mitocondrial (PMM), cinética e ultraestrutura. Os grupos Controle e GSH (2, 5 e 7mM mL-1) não diferiram (P>0,05) em iMP, iAc, PMM e cinética. Na análise ultraestrutural, os porcentuais de membrana plasmática (cabeça e cauda) e acrossoma íntegros não diferiram (P>0,05) entre grupos. Todavia, o grupo Controle apresentou maior porcentual (P<0,05) de gametas com axonema íntegros do que os de GSH (2, 5 e 7mM mL-1). Maior porcentagem (P<0,05) de espermatozoides com mitocôndrias íntegras foi observada no grupo Controle do que nos de GSH (5 e 7 mM mL-1). Conclui-se que a adição de GSH (2, 5 e 7mM mL-1) em diluente de congelação de sêmen caprino, à base de leite desnatado, não preserva a integridade dos espermatozoides.

Aiming to evaluate in vitro effect of different concentrations of glutathione reduced (GSH) in skimmed-milk and glycerol 7 percent it was used semen from five Boer bucks. After collect and evaluation, a pool of samples was diluted in skimmed-milk and glycerol 7 percent plus antioxidant: G1) Control; G2) GSH 2mM mL-1; G3) GSH 5mM mL-1 and G4) GSH 7mM mL-1. Samples were frozen in straws (0.25mL) and stored at -196°C. After thawing, samples were subjected to integrity of the plasma membrane (iMP) and acrosomal (iAc), mitochondrial membrane potential (MMP), kinematic and ultrastructure analysis. Control and GSH (2, 5 and 7mM mL-1) groups did no differ (P>0.05) in iMP, iAc, PMM and kinematic parameters. In the ultrastructural analysis, percentages of acrosome and plasma membrane (tail and head region) intact did not differ (P>0.05) between groups. However, Control group had higher percentage (P<0.05) of gametes with intact axonemes than those of GSH (2, 5 and 7mM mL-1) groups. Higher percentage (P<0.05) of sperms with intact mitochondrias were observed on Control group than those of GSH (5 and 7mM mL-1). It can be concluded that the GSH (2, 5 and 7mM mL-1) addition in skimmed-milk diluent to freeze goat semen did not preserve sperm integrity.