title: Melatonin protects inner ear against radiation damage in rats.
abstract: OBJECTIVE
  To examine the effects of N-acetyl-5-methoxytryptamine (melatonin) on radiation-induced inner ear damage.
  
  
  METHODS
  An experimental animal model.
  
  
  METHODS
  Forty rats were randomized into five groups, as follows: 1) melatonin and then radiotherapy group (n = 8), which received intraperitoneal (i.p.) melatonin (5 mg/kg) followed by irradiation 30 minutes later; 2) radiotherapy and then melatonin group (n = 8), which received irradiation with i.p. melatonin (5 mg/kg) 30 minutes later; 3) melatonin group (n = 8), which received i.p. melatonin (5 mg/kg); 4) radiotherapy group (n = 8), which underwent only irradiation; 5) and the control group (n = 8), which received i.p. 0.9% NaCl. The medications and irradiation were administered for 5 days. All rats underwent the distortion product otoacoustic emission (DPOAE) test before and 10 days after the experiment. The middle ears of the rats were excised, and assessment of tissue alterations in the organs of Corti, spiral ganglions, and stria vascularis were compared among the groups.
  
  
  RESULTS
  In the radiotherapy group, the DPOAE amplitudes at frequencies of 4000 to 6000 Hz were significantly decreased when compared with the controls. The DPOAE amplitudes both in the melatonin and then radiotherapy group and the radiotherapy and then melatonin group exhibited better values than they did in the radiotherapy group. Histopathological evidence of damage to the organs of Corti, spiral ganglions, and stria vascularis damage was markedly reduced in both these two groups when compared to the radiotherapy group.
  
  
  CONCLUSIONS
  These results indicate that melatonin may have significant ameliorative effects on cochlear damage secondary to ionizing radiation.
authors.affiliation: Department of Histology and Embriyology.
authors.forename: Isil
authors.initials: I
authors.lastname: Karaer
authors.affiliation: ENT Department, Malatya State Hospital.
authors.forename: Gokce
authors.initials: G
authors.lastname: Simsek
authors.affiliation: the Department of Pharmacology, Inönü University Faculty of Medicine, Malatya.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Gul
authors.affiliation: Inonu University Faculty of Medicine.
authors.forename: Leyla
authors.initials: L
authors.lastname: Bahar
authors.affiliation: ENT Department, Kirikkale University, Faculty of Medicine, Kirikkale.
authors.forename: Simay
authors.initials: S
authors.lastname: Gürocak
authors.affiliation: Vocational School of Health Services, Mersin University, Mersin, Turkey.
authors.forename: Hakan
authors.initials: H
authors.lastname: Parlakpinar
authors.affiliation: Department of Radiation Oncology.
authors.forename: Ayse
authors.initials: A
authors.lastname: Nuransoy
mesh_terms: D000818:Animals; D007758:Ear, Inner / Q000528:radiation effects*; D008297:Male; D008550:Melatonin / Q000627:therapeutic use*; D011832:Radiation Injuries / Q000517:prevention & control*; D011878:Radiotherapy / Q000009:adverse effects; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D008550:Melatonin
keywords: Inner ear; melatonin; otoacoustic emission; radiotherapy