title: Melatonin reduces lipid peroxidation and apoptotic-like changes in stallion spermatozoa.
abstract: Lipid peroxidation (LPO) has been claimed as a major factor involved in stallion damage during storage or cryopreservation. Because melatonin is a well-known potent antioxidant, the aim of the present study was to investigate the effect of melatonin during in vitro incubation. Furthermore, we investigated the presence of specific melatonin receptors (MT1 and MT2) using specific polyclonal antibodies and western blotting. Stallion spermatozoa were incubated up to 3 hr at 37°C in the presence of different concentrations of melatonin (0, 50 pm, 100 pm, 200 pm, or 1 μm). At the beginning and at the end of the incubation period, sperm motility (using computer-assisted sperm analysis), membrane integrity and permeability, fluidity of the sperm membrane, LPO, and mitochondrial membrane potential (Δψm) were flow cytometrically evaluated. Melatonin reduced changes in the spermatozoa related to apoptosis (increased sperm membrane permeability and lowered Δψm) (P < 0.05). Furthermore, LPO was dramatically reduced (P < 0.01) while no effect was observed on sperm motility or kinematics. Interestingly, melatonin helped maintain a more fluid sperm plasmalemma (P < 0.05). Our results clearly show the absence of MT1 and MT2 receptors in the stallion spermatozoa. It is concluded that melatonin is a useful tool to improve the quality of stored stallion sperm, increasing their life span and reducing premature aging, this likely relates to melatonin's antioxidant properties.
authors.affiliation: Laboratory of Equine Reproduction, Faculty of Veterinary Medicine, Veterinary Teaching Hospital, University of Extremadura, Cáceres, Spain.
authors.forename: Carolina M Balao
authors.initials: CM
authors.lastname: da Silva
authors.forename: Beatriz
authors.initials: B
authors.lastname: Macías-García
authors.forename: Alvaro
authors.initials: A
authors.lastname: Miró-Morán
authors.forename: Lauro
authors.initials: L
authors.lastname: González-Fernández
authors.forename: Antolín
authors.initials: A
authors.lastname: Morillo-Rodriguez
authors.forename: Cristina
authors.initials: C
authors.lastname: Ortega-Ferrusola
authors.forename: Juan M
authors.initials: JM
authors.lastname: Gallardo-Bolaños
authors.forename: George
authors.initials: G
authors.lastname: Stilwell
authors.forename: Jose A
authors.initials: JA
authors.lastname: Tapia
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Peña
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism; D016922:Cellular Senescence / Q000187:drug effects; D006736:Horses; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D008560:Membrane Fluidity / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D044094:Receptors, Melatonin / Q000378:metabolism; D012662:Semen Preservation; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D044094:Receptors, Melatonin; D008550:Melatonin