title: Elevated auditory brainstem response thresholds in mice with Connexin36 gene ablation.
abstract: CONCLUSIONS
  Expression of connexin36 (Cx36) and electrical synapses formed by Cx36-containing gap junctions contribute to normal auditory brainstem response thresholds in mice.
  
  
  OBJECTIVE
  Electrical synaptic transmission mediated by gap junctions has not been intensively studied in the auditory system. This study used transgenic mice with knockout of the gene coding for the major protein that forms neuronal gap junctions in mammalian brain (Cx36) to evaluate the role of Cx36 in murine hearing.
  
  
  METHODS
  Auditory brainstem response (ABR) thresholds and distortion product otoacoustic emissions (DPOAEs) were measured in 26 wild-type and 26 Cx36 knockout mice. ABR thresholds were used to assess auditory brainstem function at four frequencies. DPOAEs were delivered for seven frequency pairs to assess cochlear function.
  
  
  RESULTS
  The magnitudes of the 2f1-f2 distortion products were not different between Cx36 knockout and wild-type mice, suggesting similar cochlear function in the two groups. ABR thresholds were significantly elevated in the Cx36 knockout compared with the wild-type groups, suggesting impaired function in the auditory brainstem. The results suggest that electrical synapses formed by Cx36-containing gap junctions contribute to auditory sound processing and function at the level of the brainstem, not the cochlea. These findings may be important for understanding human auditory pathology.
authors.affiliation: Department of Otolaryngology, University of Manitoba , Winnipeg , Canada.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Blakley
authors.forename: Carlos E A
authors.initials: CE
authors.lastname: Garcia
authors.forename: Suzete R
authors.initials: SR
authors.lastname: da Sliva
authors.forename: Victor M B
authors.initials: VM
authors.lastname: Florêncio
authors.forename: James I
authors.initials: JI
authors.lastname: Nagy
mesh_terms: D000818:Animals; D017630:Connexins / Q000096:biosynthesis / Q000235:genetics*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D017629:Gap Junctions; D005786:Gene Expression Regulation; D034381:Hearing Loss / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D051379:Mice; D018345:Mice, Knockout; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D012313:RNA / Q000235:genetics*; D009435:Synaptic Transmission; D000097004:Gap Junction delta-2 Protein
chemical_list: D017630:Connexins; D012313:RNA; D000097004:Gap Junction delta-2 Protein
keywords: distortion product otoacoustic emissions; electrical synapses; gap junctions; hearing deficiencies; neurons