title: Mitochondrial ATP is required for the maintenance of membrane integrity in stallion spermatozoa, whereas motility requires both glycolysis and oxidative phosphorylation.
abstract: To investigate the hypothesis that oxidative phosphorylation is a major source of ATP to fuel stallion sperm motility, oxidative phosphorylation was suppressed using the mitochondrial uncouplers CCCP and 2,4,-dinitrophenol (DNP) and by inhibiting mitochondrial respiration at complex IV using sodium cyanide or at the level of ATP synthase using oligomycin-A. As mitochondrial dysfunction may also lead to oxidative stress, production of reactive oxygen species was monitored simultaneously. All inhibitors reduced ATP content, but oligomycin-A did so most profoundly. Oligomycin-A and CCCP also significantly reduced mitochondrial membrane potential. Sperm motility almost completely ceased after the inhibition of mitochondrial respiration and both percentage of motile sperm and sperm velocity were reduced in the presence of mitochondrial uncouplers. Inhibition of ATP synthesis resulted in the loss of sperm membrane integrity and increased the production of reactive oxygen species by degenerating sperm. Inhibition of glycolysis by deoxyglucose led to reduced sperm velocities and reduced ATP content, but not to loss of membrane integrity. These results suggest that, in contrast to many other mammalian species, stallion spermatozoa rely primarily on oxidative phosphorylation to generate the energy required for instance to maintain a functional Na+/K+gradient, which is dependent on an Na+-K+antiporter ATPase, which relates directly to the noted membrane integrity loss. Under aerobic conditions, however, glycolysis also provides the energy required for sperm motility.
authors: Laboratory of Equine Reproduction and Equine Spermatology. Veterinary Teaching HospitalUniversity of Extremadura, Cáceres, Spain.
authors: M Plaza
authors: MP
authors: Davila
authors: Laboratory of Equine Reproduction and Equine Spermatology. Veterinary Teaching HospitalUniversity of Extremadura, Cáceres, Spain.
authors: P Martin
authors: PM
authors: Muñoz
authors: Laboratory of Equine Reproduction and Equine Spermatology. Veterinary Teaching HospitalUniversity of Extremadura, Cáceres, Spain.
authors: J M Gallardo
authors: JM
authors: Bolaños
authors: Department of Equine Sciences.|Department of Farm Animal Health.
authors: T A E
authors: TA
authors: Stout
authors: Department of Farm Animal Health.|Department of Biochemistry and Cell BiologyFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors: B M
authors: BM
authors: Gadella
authors: Department of PhysiologyFaculty of Veterinary Medicine, University of Extremadura, Cáceres, Spain.
authors: J A
authors: JA
authors: Tapia
authors: Portalagre Polytechnic InstituteSuperior Agriculture School of Elvas, Elvas, Portugal.
authors: C Balao
authors: CB
authors: da Silva
authors: Reproduction and Obstetrics Department of Animal Medicine and SurgeryUniversity of León, León, Spain.
authors: C Ortega
authors: CO
authors: Ferrusola
authors: Laboratory of Equine Reproduction and Equine Spermatology. Veterinary Teaching HospitalUniversity of Extremadura, Cáceres, Spain fjuanpvega@unex.es.
authors: F J
authors: FJ
authors: Peña
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D004734:Energy Metabolism; D006019:Glycolysis / Q000502:physiology*; D006736:Horses; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D013081:Sperm Motility / Q000502:physiology*; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate