title: Decrease in glutathione content in boar sperm after cryopreservation. Effect of the addition of reduced glutathione to the freezing and thawing extenders.
abstract: Although glutathione content in boar spermatozoa has been previously reported, the effect of reduced glutathione (GSH) on semen parameters and the fertilizing ability of boar spermatozoa after cryopreservation has never been evaluated. In this study, GSH content was determined in ejaculated boar spermatozoa before and after cryopreservation. Semen samples were centrifuged and GSH content in the resulting pellet monitored spectrophotometrically. The fertilizing ability of frozen-thawed boar sperm was also tested in vitro by incubating sperm with in vitro matured oocytes obtained from gilts. GSH content in fresh semen was 3.84 +/- 0.21 nM GSH/10(8) sperm. Following semen cryopreservation, there was a 32% decrease in GSH content (P < 0.0001). There were significant differences in sperm GSH content between different boars and after various preservation protocols (P = 0.0102 ). The effect of addition of GSH to the freezing and thawing extenders was also evaluated. Addition of 5 mM GSH to the freezing extender did not have a significant effect on standard semen parameters or sperm fertilizing ability after thawing. In contrast, when GSH was added to the thawing extender, a dose-dependent tendency to increase in sperm fertilizing ability was observed, although no differences were observed in standard semen parameters. In summary, (i) there was a loss in GSH content after cryopreservation of boar semen; (ii) addition of GSH to the freezing extender did not result in any improvement in either standard semen parameters or sperm fertilizing ability; and (iii) addition of GSH to the thawing extender resulted in a significant increase in sperm fertilizing ability. Nevertheless, future studies must conclude if this is the case for all boars. Furthermore, since addition of GSH to the thawing extender did not result in an improvement in standard semen parameters, this suggests that during the thawing process, GSH prevents damage of a sperm property that is critical in the fertilization process but that is not measured in the routine semen analysis.
authors.affiliation: Department of Physiology, Facultad de Veterinaria, School of Veterinary, Campus de Espinardo, University of Murcia, Murcia 30071, Spain. jgadea@um.es
authors.forename: Joaquín
authors.initials: J
authors.lastname: Gadea
authors.forename: Elena
authors.initials: E
authors.lastname: Sellés
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Marco
authors.forename: Pilar
authors.initials: P
authors.lastname: Coy
authors.forename: Carmen
authors.initials: C
authors.lastname: Matás
authors.forename: Raquel
authors.initials: R
authors.lastname: Romar
authors.forename: Salvador
authors.initials: S
authors.lastname: Ruiz
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000662:veterinary*; D005260:Female; D005307:Fertilization in Vitro; D005978:Glutathione / Q000008:administration & dosage* / Q000032:analysis* / Q000737:chemistry; D006358:Hot Temperature; D008297:Male; D010084:Oxidation-Reduction; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013094:Spermatozoa / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology; D013552:Swine
chemical_list: D005978:Glutathione