title: Caspase activation, hydrogen peroxide production and Akt dephosphorylation occur during stallion sperm senescence.
abstract: To investigate the mechanisms inducing sperm death after ejaculation, stallion ejaculates were incubated in BWW media during 6 h at 37°C. At the beginning of the incubation period and after 1, 2, 4 and 6 h sperm motility and kinematics (CASA), mitochondrial membrane potential and membrane permeability and integrity were evaluated (flow cytometry). Also, at the same time intervals, active caspase 3, hydrogen peroxide, superoxide anion (flow cytometry) and Akt phosphorylation (flow cytometry) were evaluated. Major decreases in sperm function occurred after 6 h of incubation, although after 1 h decrease in the percentages of motile and progressive motile sperm occurred. The decrease observed in sperm functionality after 6 h of incubation was accompanied by a significant increase in the production of hydrogen peroxide and the greatest increase in caspase 3 activity. Additionally, the percentage of phosphorylated Akt reached a minimum after 6 h of incubation. These results provide evidences that sperm death during in vitro incubation is largely an apoptotic phenomena, probably stimulated by endogenous production of hydrogen peroxide and the lack of prosurvival factors maintaining Akt in a phosphorylated status. Disclosing molecular mechanisms leading to sperm death may help to develop new strategies for stallion sperm conservation.
authors.affiliation: Laboratory of Equine Reproduction and Equine Spermatology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Gallardo Bolaños
authors.affiliation: Laboratory of Equine Reproduction and Equine Spermatology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Balao da Silva
authors.affiliation: Laboratory of Equine Reproduction and Equine Spermatology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Martín Muñoz
authors.affiliation: Laboratory of Equine Reproduction and Equine Spermatology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Plaza Dávila
authors.affiliation: Faculty of Veterinary Medicine, Veterinary Teaching Hospital, University of Extremadura, Cáceres, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Ezquerra
authors.affiliation: Department of Physiology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: I M
authors.initials: IM
authors.lastname: Aparicio
authors.affiliation: Department of Physiology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Tapia
authors.affiliation: Laboratory of Equine Reproduction and Equine Spermatology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Ortega Ferrusola
authors.affiliation: Laboratory of Equine Reproduction and Equine Spermatology, Faculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Peña
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D020169:Caspases / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000502:physiology; D016922:Cellular Senescence / Q000502:physiology*; D004789:Enzyme Activation; D005434:Flow Cytometry / Q000662:veterinary; D006736:Horses / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012662:Semen Preservation / Q000662:veterinary; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure; D013997:Time Factors
chemical_list: D006861:Hydrogen Peroxide; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases