Efeitos da glutationa reduzida sobre os processos de capacitação e reação acrossômica in vitro em espermatozoides suínos refrigerados

Abstract

A study was conducted with the objective of evaluating the effects of reduced glutathione (GSH) over spermatic function during capacitation and posterior induction of acrosome reaction in vitro, in refrigerated pig semen. This was done by evaluating many in vitro capacitation markers and other global parameters of semen quality, such as feasibility, total motility, acrosome exocytosis induced by progesterone, DNA fragmentation, levels of lipid disorders in the spermatic membrane, reactive oxygen species (ROS), free cysteine residue in sperm head and tail extracts and protein phosphorylation of tyrosine residue. A total of 62 ejaculates derived from 35 healthy breeding Pietrain pigs, between 2 and 3 years of age, were used in the different analyses conducted in this work. The addition of GHS in the capacitation medium (CM) prevented most changes consequent to capacitation. In addition, the GSH caused quick fall and intense total motility (P < 0.05), which was maintained during the entire incubation period. Despite these results, the GH did not affect the beginning of in vitro acrosome exocytosis induced by progesterone (IVAE), observed after four hours of CM incubation. The results showed that in vitro pig semen capacitation is related to the significant increase of both total break of disulfide bonds and the levels of intracellular ROS. These phenomena can fulfill a role in obtaining the capacitating state of the spermatic cell, although they are not fundamental in performing the posterior IVAE. Finally, spermatozoid motility seems to be partially controlled by ionic and oxidation-reduction mechanisms, as was indicated by the GSH incubation in separate conditions. Therefore, this study demonstrates the existence of parallel and separated paths within the spermatic capacitation events controlled by the GSH, thus contributing for the better understanding of these phenomena, and brings a new direction for future works in this line of research.