title: Addition of superoxide dismutase mimics during cooling process prevents oxidative stress and improves semen quality parameters in frozen/thawed ram spermatozoa.
abstract: High levels of reactive oxygen species (ROS), which may be related to reduced semen quality, are detected during semen cryopreservation in some species. The objectives of this study were to measure the oxidative stress during ram semen cryopreservation and to evaluate the effect of adding 2 antioxidant mimics of superoxide dismutase (Tempo and Tempol) during the cooling process on sperm motility, viability, acrosomal integrity, capacitation status, ROS levels, and lipid peroxidation in frozen and/or thawed ram spermatozoa. Measuring of ROS levels during the cooling process at 35, 25, 15, and 5 °C and after freezing and/or thawing showed a directly proportional increase (P < 0.05) when temperatures were lowering. Adding antioxidants at 10 °C confered a higher motility and sperm viability after cryopreservation in comparison with adding at 35 °C or at 35 °C/5 °C. After freezing and/or thawing, sperm motility was significantly higher (P < 0.05) in Tempo and Tempol 1 mM than that in control group. Percentage of capacitated spermatozoa was lower (P < 0.05) in Tempo and Tempol 1 mM in comparison with that in control group. In addition, ROS levels and lipid peroxidation in group Tempo 1 mM were lower (P < 0.05) than those in control group. These results demonstrate that ram spermatozoa are exposed to oxidative stress during the cooling process, specifically when maintained at 5 °C and that lipid peroxidation induced by high levels of ROS decreases sperm motility and induces premature sperm capacitation. In contrast, the addition of Tempo or Tempol at 0.5 to 1 mM during the cooling process (10 °C) protects ram spermatozoa from oxidative stress.
authors.affiliation: Laboratory of Animal Reproduction, Faculty of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Perú. Electronic address: asantiani@hotmail.com.
authors.forename: Alexei
authors.initials: A
authors.lastname: Santiani
authors.affiliation: Laboratory of Animal Reproduction, Faculty of Veterinary Medicine, Universidad Nacional Mayor de San Marcos, Lima, Perú
authors.forename: Shirley
authors.initials: S
authors.lastname: Evangelista
authors.affiliation: Center of Biotechnology in Reproduction (BIOREN-CEBIOR), Faculty of Medicine, Universidad de La Frontera, Temuco, Chile.
authors.forename: Néstor
authors.initials: N
authors.lastname: Sepúlveda
authors.affiliation: Center of Biotechnology in Reproduction (BIOREN-CEBIOR), Faculty of Medicine, Universidad de La Frontera, Temuco, Chile.
authors.forename: Jennie
authors.initials: J
authors.lastname: Risopatrón
authors.affiliation: Center of Biotechnology in Reproduction (BIOREN-CEBIOR), Faculty of Medicine, Universidad de La Frontera, Temuco, Chile.
authors.forename: Juana
authors.initials: J
authors.lastname: Villegas
authors.affiliation: Center of Biotechnology in Reproduction (BIOREN-CEBIOR), Faculty of Medicine, Universidad de La Frontera, Temuco, Chile.
authors.forename: Raúl
authors.initials: R
authors.lastname: Sánchez
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000662:veterinary; D003451:Cryoprotective Agents / Q000494:pharmacology*; D003497:Cyclic N-Oxides / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects*; D055101:Semen Analysis / Q000662:veterinary*; D012662:Semen Preservation / Q000662:veterinary*; D012756:Sheep / Q000502:physiology*; D013094:Spermatozoa / Q000187:drug effects* / Q000502:physiology; D013113:Spin Labels
chemical_list: D003451:Cryoprotective Agents; D003497:Cyclic N-Oxides; D013113:Spin Labels; C001803:tempol; C003959:TEMPO
keywords: Cryopreservation; Oxidative stress; Ram sperm; Superoxide dismutase; Tempo; Tempol