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

Abstract

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%, 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 (PAiming to evaluate in vitro effect of different concentrations of glutathione reduced (GSH) in skimmed-milk and glycerol 7% it was used semen from five Boer bucks. After collect and evaluation, a pool of samples was diluted in skimmed-milk and glycerol 7% 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.

Keywords

• antioxidantes
• sêmen
• viabilidade espermática
• antioxidants
• semen
• sperm viability