title: In vitro and in vivo effects of melatonin on sister chromatid exchange in human blood lymphocytes exposed to hypoxia.
abstract: OBJECTIVE
  Many studies have shown that melatonin (MLT) has an anti-genotoxic effect in various tissues and cell lines. The aim of this study was to investigate the anti-genotoxic effect of MLT on normal human peripheral lymphocytes by assessing sister chromatid exchange (SCE) in vitro and in vivo.
  
  
  METHODS
  Cells were treated with 50 and 200 μM of MLT. The human volunteers (n = 20) for the in vivo study were administered a single dose of 3 mg MLT daily for 2 weeks. After sufficient time for its clearance, 1.5 mg of MLT daily was then administered to the same volunteers at same the period.
  
  
  RESULTS
  Our results demonstrated the anti-genotoxic effect of MLT in human blood lymphocyte in vitro and in vivo. In vitro, hypoxia increased the SCE frequency compared to the control and both doses of MLT significantly decreased the SCE frequency in the hypoxic cells (p < 0.001). In vivo, oral administration of 3 mg MLT significantly increased the frequency of SCE, yet a small increase of SCE by hypoxia was found. Oral administration of 1.5 mg MLT showed no DNA damage but it had an anti-genotoxic effect.
  
  
  CONCLUSIONS
  MLT may prove useful for reducing the genotoxic effects of hypoxia in peripheral lymphocytes and suggest its possible role for ischemic diseases.
authors.affiliation: a Department of Anatomy .
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: b Medical Course .
authors.forename: Ki-Sang
authors.initials: KS
authors.lastname: Eom
authors.affiliation: c Department of Physiology .
authors.forename: Dae-Kyu
authors.initials: DK
authors.lastname: Song
authors.affiliation: d Department of Microbiology , and.
authors.forename: Sung-Il
authors.initials: SI
authors.lastname: Suh
authors.affiliation: e Department of Medical Genetics , College of Medicine, Keimyung University , Daegu , Republic of Korea , and.|f Hanvit Institute for Medical Genetics , Daegu , Republic of Korea.
authors.forename: Dae-Kwang
authors.initials: DK
authors.lastname: Kim
mesh_terms: D000284:Administration, Oral; D000328:Adult; D016587:Antimutagenic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D015687:Cell Hypoxia / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D064368:Healthy Volunteers; D006801:Humans; D000860:Hypoxia / Q000235:genetics*; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D012854:Sister Chromatid Exchange / Q000187:drug effects* / Q000235:genetics; D055815:Young Adult
chemical_list: D016587:Antimutagenic Agents; D008550:Melatonin
keywords: Cytogenetic; DNA damage; hypoxia; melatonin; sister chromatid exchange