title: Influence of methionine and dithioerythritol on sperm motility, lipid peroxidation and antioxidant capacities during liquid storage of ram semen.
abstract: The aim of this study was to investigate the effects of methionine and dithioerythritol, added to the Tris extender, on ram sperm motility and LPO (lipid peroxidation) and antioxidant capacities during liquid storage up to 72 h at 5°C. Ejaculates collected from five Merino rams, were evaluated and pooled at 37°C. This study included two experiments. In experiment 1, each pooled ejaculate was divided into four equal aliquots and diluted (37°C) with the base extender, containing 0 (control), 1, 2 and 4 mM methionine, at a final concentration of approximately 4×10(8)sperms/ml (single step dilution), in a 15-ml plastic centrifuge tube. In experiment 2, dithioerythritol, at concentrations of 0 (control), 0.5, 1 and 2 mM, was used as an additive in the extender, and the procedure explained above was applied for the division of aliquots and the dilution of semen. Diluted semen samples were kept in glass tubes and cooled from 37 to 5°C in a cold cabinet, and maintained at 5°C. Sperm motility and LPO and total glutathione (GSH) and glutathione peroxidase (GPx) capacities were determined at 5°C for periods of 0, 24, 48 and 72 h of liquid storage. The extender supplemented with 1 mM methionine led to higher motility percentages (77.0±1.2%), in comparison to the control group (66.0±4.9%), during 72 h of liquid storage (P<0.05). As regards dithioerythritol, it did not statistically improve the motility rates for any of the storage times at 5°C. In biochemical assays, differences in LPO levels between the groups with antioxidants and the control groups were not statistically significant. Compared to the control group, no significant difference was observed in GSH and GPx activities following the addition of methionine, during 72 h of storage. Total GSH and GPx activities did not increase significantly upon supplementation with 0.5 and 1 mM of dithioerythritol, compared to the control group, at any of the time points (P>0.05). Dithioerythritol at 2 mM led (P<0.01) to elevating GSH activity, compared to the control group, during 72 h of liquid storage. GPx activity was approximately 10 times higher for 2 mM of dithioerythritol (P<0.001), compared to that of the control group at all time points. The question regarding the sustainability of sperm survival, LPO and antioxidant capacities following liquid storage of semen remains unanswered. Further studies are required for a better understanding of the biochemical changes and to obtain more information on the determination of lipid peroxidation and antioxidant capacities during cooled storage of ram semen.
authors.affiliation: Selcuk University, Faculty of Veterinary Medicine, Department of Reproduction and Artificial Insemination, Konya, Turkey.
authors.forename: Kenan
authors.initials: K
authors.lastname: Coyan
authors.forename: Nuri
authors.initials: N
authors.lastname: Başpınar
authors.forename: Mustafa Numan
authors.initials: MN
authors.lastname: Bucak
authors.forename: Pınar Peker
authors.initials: PP
authors.lastname: Akalın
authors.forename: Mehmet Bozkurt
authors.initials: MB
authors.lastname: Ataman
authors.forename: Ali Doğan
authors.initials: AD
authors.lastname: Omür
authors.forename: Sükrü
authors.initials: S
authors.lastname: Güngör
authors.forename: Sadık
authors.initials: S
authors.lastname: Küçükgünay
authors.forename: Birol
authors.initials: B
authors.lastname: Ozkalp
authors.forename: Serpil
authors.initials: S
authors.lastname: Sarıözkan
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D004226:Dithioerythritol / Q000494:pharmacology*; D005978:Glutathione / Q000032:analysis; D005979:Glutathione Peroxidase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008715:Methionine / Q000494:pharmacology*; D012661:Semen / Q000187:drug effects* / Q000378:metabolism; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D012756:Sheep; D013081:Sperm Motility / Q000187:drug effects*; D013094:Spermatozoa / Q000737:chemistry / Q000187:drug effects
chemical_list: D000975:Antioxidants; D004226:Dithioerythritol; D008715:Methionine; D005979:Glutathione Peroxidase; D005978:Glutathione