title: Brain-derived neurotrophic factor treatment does not improve functional recovery after hair cell regeneration in the pigeon.
abstract: CONCLUSIONS
  Brain-derived neurotrophic factor (BDNF) supply to the inner ear does not improve the time course or the extent of functional recovery after hair cell regeneration. Specifically it does not improve the residual threshold elevation observed after the completion of spontaneous recovery.
  
  
  OBJECTIVE
  The avian inner ear is capable of hair cell regeneration and substantial functional recovery, but residual hearing deficits remain. We investigated whether functional recovery can be improved by intracochlear application of BDNF, which plays an important role in auditory ontogenesis and maintenance during adult life.
  
  
  METHODS
  Hair cells in adult pigeons were destroyed by local application of gentamicin. After 3 days either BDNF or control solution was administered to the scala tympani by implanted osmotic minipumps for 8 weeks. Auditory brain stem responses (ABR) to tone pips were used to assess recovery of hearing thresholds in both groups.
  
  
  RESULTS
  The application of gentamicin caused a frequency-dependent hearing loss that ranged from 24.8 dB SPL at low frequencies to 66.2 dB SPL at high frequencies. After day 10 substantial recovery was observed, but a significant threshold shift remained. The time course of recovery in the control and BDNF-treated groups was similar, without significant residual threshold differences in any frequency range.
authors.affiliation: Physiologisches Institut II, Zentrum der Hals-Nasen-Ohrenheilkunde, Frankfurt am Main, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Radeloff
authors.forename: J W Th
authors.initials: JW
authors.lastname: Smolders
mesh_terms: D000287:Administration, Topical; D000818:Animals; D001309:Auditory Threshold / Q000187:drug effects* / Q000502:physiology; D019208:Brain-Derived Neurotrophic Factor / Q000494:pharmacology*; D003051:Cochlea / Q000187:drug effects / Q000503:physiopathology; D010856:Columbidae; D003638:Deafness / Q000503:physiopathology*; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects / Q000502:physiology; D005839:Gentamicins / Q000633:toxicity; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000503:physiopathology; D008144:Loudness Perception / Q000187:drug effects / Q000502:physiology; D009416:Nerve Regeneration / Q000187:drug effects* / Q000502:physiology; D010898:Pitch Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D005839:Gentamicins