title: Nitric oxide induces apoptosis of the hair cells of cochlea.
abstract: OBJECTIVE
  Nitric oxide (NO) has a toxic effect on neuronal cells related to glutamate receptors. NO released from post-synaptic cells with glutamate receptors can induce nearby cell death. In this experiment, we examined the effect of NO on cochlear hair cells.
  
  
  METHODS
  Two concentrations, 0.5 and 0.1 molar concentration (MC) of 1-hydroxy-2-oxo-3-(3-aminopropyl)-3-isopropyl-1-triazene (NOC-5), which is a NO donor, were placed on the round window of the guinea pig cochlea and its morphological changes were investigated at 12, 28, 72 h after the treatment.
  
  
  RESULTS
  By the trypan blue dye extrusion method, the cell death was recognized in the outer hair cells at the percentage 0, 36.0+/-6.6, 4.9+/-1.2% at 12, 28, 72 h after treatment respectively in the group 0.5 MC NOC-5, but no inner hair cell death was recognized. In the group of 0.1 MC NOC-5 and control any cell death was not detected. Transmission electron microscopy revealed this cell death was characteristic of apoptosis.
  
  
  CONCLUSIONS
  The findings that apoptosis was induced in the outer hair cells of the organ of Corti by NO suggests the possibility that the cochlea is affected when extra NO release occurs there, leading to cochlear dysfunction.
authors.affiliation: Department of Otolaryngology and Head & Neck Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan. ent-yamane@med.osaka-cu.ac.jp
authors.forename: Hideo
authors.initials: H
authors.lastname: Yamane
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takayama
authors.forename: Kishiko
authors.initials: K
authors.lastname: Sunami
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Iguchi
authors.forename: Akimori
authors.initials: A
authors.lastname: Kanazawa
authors.forename: Yasutake
authors.initials: Y
authors.lastname: Tokuhara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishiura
authors.forename: Keizou
authors.initials: K
authors.lastname: Nishimura
authors.forename: Shu Dong
authors.initials: SD
authors.lastname: Tao
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D003051:Cochlea / Q000473:pathology / Q000648:ultrastructure; D016166:Free Radical Scavengers / Q000633:toxicity*; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000166:cytology* / Q000187:drug effects* / Q000648:ultrastructure; D008854:Microscopy, Electron; D009569:Nitric Oxide / Q000633:toxicity*; D012405:Round Window, Ear; D014226:Triazenes / Q000008:administration & dosage / Q000378:metabolism
chemical_list: C114535:1-hydroxy-2-oxo-3-(3-aminopropyl)-3-isopropyl-1-triazene; D016166:Free Radical Scavengers; D014226:Triazenes; D009569:Nitric Oxide