title: Hearing impairment, cochlear morphology, and peroxynitrite (ONOO(-)) formation in adult and aging NOS II knockout mice.
abstract: CONCLUSIONS
  Nitric oxide synthase (NOS) II induction is a protective mechanism against age-related degeneration of the cochlea.
  
  
  OBJECTIVE
  An induction of NOS II has been described in different inner ear pathologies. The objective was to examine the role of NOS II in age-related degeneration of the cochlea.
  
  
  METHODS
  The hearing ability in adult and aging NOS II knockout mice (KO) and their wildtype (WT) littermates was explored via auditory brainstem response (ABR) measurements. Inner ear morphological differences were studied with scanning electron microscopy (SEM). Immunohistochemistry was used to examine the induction of NOS II in the inner ear of aging WT mice. Expression of nitrotyrosin, a marker protein for the reactive oxygen species peroxynitrite, was compared between KO and WT mice using immunohistochemistry.
  
  
  RESULTS
  Adult KO mice exhibited a mild hearing impairment. WT mice showed an induction of NOS II after 6 months of age. Age-related hearing deterioration was accelerated in KO mice, which was accompanied by increased nitrotyrosin formation and outer hair cell loss.
authors.affiliation: a Department of Otorhinolaryngology , University Clinics of the Saarland , Homburg , Germany ;
authors.forename: Daniel
authors.initials: D
authors.lastname: Labbé
authors.affiliation: b Department of Molecular and Cellular Sport Medicine , German Sport University , Cologne , Germany ;
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Bloch
authors.affiliation: a Department of Otorhinolaryngology , University Clinics of the Saarland , Homburg , Germany ;
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schick
authors.affiliation: c Afdelingshoofd Dienst KNO , Universitair Ziekenhuis -Vrije Universiteit Brussel UZ-VUB , Brussels , Belgium.
authors.forename: Olaf
authors.initials: O
authors.lastname: Michel
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D003051:Cochlea / Q000473:pathology / Q000502:physiology*; D005260:Female; D034381:Hearing Loss / Q000201:enzymology* / Q000473:pathology; D007150:Immunohistochemistry; D018345:Mice, Knockout; D052247:Nitric Oxide Synthase Type II / Q000502:physiology*; D030421:Peroxynitrous Acid / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D030421:Peroxynitrous Acid; C002744:3-nitrotyrosine; D014443:Tyrosine; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse
keywords: Nitric oxide; cochlea; hearing loss; peroxynitrite