title: Melatonin receptors MT1 and MT2 are expressed in spermatozoa from several seasonal and nonseasonal breeder species.
abstract: Melatonin is a ubiquitous and multipurpose molecule, and one of its roles is to regulate reproduction in some seasonal mammals. Our group has previously reported the variation in the melatonin levels in ram seminal plasma along the year and identified MT1 and MT2 receptors in ram spermatozoa. The objective of this study was to elucidate whether the presence of melatonin receptors (MT1 and MT2) in the sperm plasma membrane, and melatonin in the seminal plasma is related to seasonal breeding. For this purpose, the presence of melatonin receptors and the levels of melatonin in seminal plasma have been examined in several species: donkey and stallion as long-day breeders; red deer as a wild, short-day, highly seasonal breeder (epididymal spermatozoa); bull as a conventional nonseasonal breeder; boar as a seasonal breeder under management techniques; and dog as possible a seasonal breeder not regulated by melatonin. We have detected measurable levels of melatonin in the seminal plasma of all ejaculated semen samples (from donkey, stallion, boar, bull, and dog). Also, and for the first time, we have demonstrated the presence of MT1 and MT2 melatonin receptors in the spermatozoa of all these species, regardless their type of reproduction or sperm source (ejaculated or epididymal), using indirect immunofluorescence techniques and Western blotting. Our findings suggest that melatonin and melatonin receptors may be universally distributed in the reproductive system of mammals and that the sperm melatonin receptors cells may not be necessarily related with seasonal reproduction. Furthermore, the presence of MT1 at the cytoplasmic droplet in immature ejaculated stallion spermatozoa found in one sample and epididymal red deer spermatozoa suggests that melatonin may be involved in specific functions during spermatogenesis and sperm maturation, like protecting spermatozoa from oxidative damage, this activity being mediated through these receptors.
authors.affiliation: Grupo Biología y Fisiología de la Reproducción, Facultad de Veterinaria, Instituto de Investigación de Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: González-Arto
authors.affiliation: Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Vicente-Carrillo
authors.affiliation: INDEGSAL, Facultad de Veterinaria, Universidad de León, León, Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Martínez-Pastor
authors.affiliation: INDEGSAL, Facultad de Veterinaria, Universidad de León, León, Spain.
authors.forename: Estela
authors.initials: E
authors.lastname: Fernández-Alegre
authors.affiliation: Departamento de Medicina y Cirugía Animal, Universidad de Murcia, Murcia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Roca
authors.affiliation: Departamento de Reproducción Animal, Facultad de Veterinaria, Universidad Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Miró
authors.affiliation: Departamento de Reproducción Animal, Facultad de Veterinaria, Universidad Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Rigau
authors.affiliation: Departamento de Reproducción Animal, Facultad de Veterinaria, Universidad Autónoma de Barcelona, Barcelona, Spain.
authors.forename: Joan E
authors.initials: JE
authors.lastname: Rodríguez-Gil
authors.affiliation: Grupo Biología y Fisiología de la Reproducción, Facultad de Veterinaria, Instituto de Investigación de Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain.
authors.forename: Rosaura
authors.initials: R
authors.lastname: Pérez-Pé
authors.affiliation: Grupo Biología y Fisiología de la Reproducción, Facultad de Veterinaria, Instituto de Investigación de Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Muiño-Blanco
authors.affiliation: Grupo Biología y Fisiología de la Reproducción, Facultad de Veterinaria, Instituto de Investigación de Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Cebrián-Pérez
authors.affiliation: Grupo Biología y Fisiología de la Reproducción, Facultad de Veterinaria, Instituto de Investigación de Ciencias Ambientales de Aragón (IUCA), Universidad de Zaragoza, Zaragoza, Spain. Electronic address: adriana@unizar.es.
authors.forename: Adriana
authors.initials: A
authors.lastname: Casao
mesh_terms: D000818:Animals; D004285:Dogs / Q000502:physiology*; D018397:Equidae / Q000502:physiology*; D008297:Male; D008550:Melatonin / Q000235:genetics / Q000378:metabolism; D044122:Receptor, Melatonin, MT1 / Q000235:genetics / Q000378:metabolism*; D044123:Receptor, Melatonin, MT2 / Q000235:genetics / Q000378:metabolism*; D012098:Reproduction / Q000502:physiology; D012621:Seasons; D012661:Semen / Q000737:chemistry / Q000378:metabolism; D013045:Species Specificity; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D044122:Receptor, Melatonin, MT1; D044123:Receptor, Melatonin, MT2; D008550:Melatonin
keywords: Boar; Bull; Deer; Dog; Donkey; Stallion