title: Intracochlear electrical stimulation suppresses apoptotic signaling in rat spiral ganglion neurons after deafening in vivo.
abstract: OBJECTIVE
  To establish the intracellular consequences of electrical stimulation to spiral ganglion neurons after deafferentation. Here we use a rat model to determine the effect of both low and high pulse rate acute electrical stimulation on activation of the proapoptotic transcription factor Jun in deafferented spiral ganglion neurons in vivo.
  
  
  METHODS
  Experimental animal study.
  
  
  METHODS
  Hearing research laboratories of the University of Iowa Departments of Biology and Otolaryngology.
  
  
  METHODS
  A single electrode was implanted through the round window of kanamycin-deafened rats at either postnatal day 32 (P32, n = 24) or P60 (n = 22) for 4 hours of stimulation (monopolar, biphasic pulses, amplitude twice electrically evoked auditory brainstem response [eABR] threshold) at either 100 or 5000 Hz. Jun phosphorylation was assayed by immunofluorescence to quantitatively assess the effect of electrical stimulation on proapoptotic signaling.
  
  
  RESULTS
  Jun phosphorylation was reliably suppressed by 100 Hz stimuli in deafened cochleae of P32 but not P60 rats. This effect was not significant in the basal cochlear turns. Stimulation frequency may be consequential: 100 Hz was significantly more effective than was 5 kHz stimulation in suppressing phospho-Jun.
  
  
  CONCLUSIONS
  Suppression of Jun phosphorylation occurs in deafferented spiral ganglion neurons after only 4 hours of electrical stimulation. This finding is consistent with the hypothesis that electrical stimulation can decrease spiral ganglion neuron death after deafferentation.
authors.affiliation: Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Kopelovich
authors.forename: Alain P
authors.initials: AP
authors.lastname: Cagaanan
authors.forename: Charles A
authors.initials: CA
authors.lastname: Miller
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Abbas
authors.forename: Steven H
authors.initials: SH
authors.lastname: Green
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D003054:Cochlear Implants; D003638:Deafness / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D004195:Disease Models, Animal; D004558:Electric Stimulation / Q000379:methods*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D006309:Hearing / Q000502:physiology*; D051381:Rats; D013136:Spiral Ganglion / Q000473:pathology* / Q000503:physiopathology
keywords: apoptosis; c-Jun; cochlear implants; deafness; phosphorylation; spiral ganglion neuron
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