title: Melatonin protects human spermatozoa from apoptosis via melatonin receptor- and extracellular signal-regulated kinase-mediated pathways.
abstract: OBJECTIVE
  To evaluate whether the protective effect of melatonin on H2O2-induced caspase activation and DNA fragmentation depends on the interaction between melatonin and its surface receptors.
  
  
  METHODS
  Laboratory study.
  
  
  METHODS
  Center for assisted human reproduction at a Spanish hospital.
  
  
  METHODS
  Twenty-one healthy donors.
  
  
  METHODS
  Human spermatozoa were treated with increasing concentrations of hydrogen peroxide (H2O2; 1 μM, 10 μM, 100 μM, 1 mM) and preincubated with 1 mM melatonin.
  
  
  METHODS
  Activation of caspase-3 and -9 as well as DNA fragmentation were examined by fluorescence methods.
  
  
  RESULTS
  Our findings showed that H2O2 induced a significant increase in caspase-9 and caspase-3, which was dose independent. Conversely, pretreatment with melatonin reduced H2O2-mediated caspase activation in a dose-dependent way. Moreover, the antiapoptotic effects of melatonin in ejaculated human spermatozoa may involve membrane melatonin receptor MT1. In addition, we found that the survival-promoting pathway extracellular signal-regulated kinase (ERK) is likely to have a role in the protective actions of melatonin in ejaculated human spermatozoa. Finally, we confirmed these results further by demonstrating that melatonin prevention of H2O2-induced DNA fragmentation is dependent on both MT1 receptor and ERK signaling.
  
  
  CONCLUSIONS
  These results indicate that the stimulation with melatonin triggers a set of events culminating in cell death prevention in ejaculated human spermatozoa.
authors.affiliation: Department of Physiology, Neuroimmunophysiology and Chrononutrition Research Group, Faculty of Science, University of Extremadura, Badajoz, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Espino
authors.forename: Águeda
authors.initials: Á
authors.lastname: Ortiz
authors.forename: Ignacio
authors.initials: I
authors.lastname: Bejarano
authors.forename: Graciela M
authors.initials: GM
authors.lastname: Lozano
authors.forename: Fabian
authors.initials: F
authors.lastname: Monllor
authors.forename: Juan F
authors.initials: JF
authors.lastname: García
authors.forename: Ana B
authors.initials: AB
authors.lastname: Rodríguez
authors.forename: José A
authors.initials: JA
authors.lastname: Pariente
mesh_terms: D000704:Analysis of Variance; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D019610:Cytoprotection; D004305:Dose-Response Relationship, Drug; D004542:Ejaculation; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D016877:Oxidants / Q000633:toxicity; D044122:Receptor, Melatonin, MT1 / Q000819:agonists* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology
chemical_list: D016877:Oxidants; D044122:Receptor, Melatonin, MT1; D006861:Hydrogen Peroxide; D048049:Extracellular Signal-Regulated MAP Kinases; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D008550:Melatonin