title: Involvement of p53 and Bcl-2 in sensory cell degeneration in aging rat cochleae.
abstract: CONCLUSIONS
  p53 and Bcl-2 (B-cell lymphoma 2) are involved in the process of sensory cell degeneration in aging cochleae.
  
  
  OBJECTIVE
  To determine molecular players in age-related hair cell degeneration, this study examined the changes in p53 and Bcl-2 expression at different stages of apoptotic and necrotic death of hair cells in aging rat cochleae.
  
  
  METHODS
  Young (3-4 months) and aging (23-24 months) Fisher 344/NHsd rats were used. The thresholds of the auditory brainstem response (ABR) were measured to determine the auditory function. Immunolabeling was performed to determine the expression of p53 and Bcl-2 proteins in the sensory epithelium. Propidium iodide staining was performed to determine the morphologic changes in hair cell nuclei.
  
  
  RESULTS
  Aging rats exhibited a significant elevation in ABR thresholds at all tested frequencies (p < 0.001). The p53 and Bcl-2 immunoreactivity was increased in aging hair cells showing the early signs of apoptotic changes in their nuclei. The Bcl-2 expression increase was also observed in hair cells displaying early signs of necrosis. As the hair cell degenerative process advanced, p53 and Bcl-2 immunoreactivity became reduced or absent. In the areas where no detectable nuclear staining was present, p53 and Bcl-2 immunoreactivity was absent.
authors.affiliation: a Department of Respiratory Diseases , Chinese PLA General Hospital , Beijing , PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Xu
authors.affiliation: b Center for Hearing and Deafness, State University of New York at Buffalo , Buffalo , NY , USA.|c Department of Otolaryngology and Head & Neck Surgery , Institute of Otolaryngology, Chinese PLA General Hospital , Beijing , PR China.
authors.forename: Wei Ping
authors.initials: WP
authors.lastname: Yang
authors.affiliation: b Center for Hearing and Deafness, State University of New York at Buffalo , Buffalo , NY , USA.
authors.forename: Bo Hua
authors.initials: BH
authors.lastname: Hu
authors.affiliation: c Department of Otolaryngology and Head & Neck Surgery , Institute of Otolaryngology, Chinese PLA General Hospital , Beijing , PR China.
authors.forename: Shiming
authors.initials: S
authors.lastname: Yang
authors.affiliation: b Center for Hearing and Deafness, State University of New York at Buffalo , Buffalo , NY , USA.
authors.forename: Donald
authors.initials: D
authors.lastname: Henderson
mesh_terms: D000375:Aging / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D017209:Apoptosis; D016057:Evoked Potentials, Auditory, Brain Stem; D006198:Hair Cells, Auditory / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009336:Necrosis; D011304:Presbycusis / Q000209:etiology* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011916:Rats, Inbred F344; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53
keywords: Bcl-2; aging; apoptosis; hair cell; necrosis; p53; rat