Death pathways in noise-exposed outer hair cells

Details

• Personal Author:
  Bohne BA ; Harding GW ; Lee SC
• Description:
  Using morphological criteria, death pathways in OHCs were determined in Organs of Corti (OC) exposed to an octave band of noise (OBN) with a center frequency of either 0.5 or 4 kHz at a moderate sound pressure level (SPL). The specimens were part of our collection of plastic-embedded flat preparations of chinchilla cochleae. Three death pathways were identified: 1) oncosis - OHCs were swollen & pale-staining with a swollen nucleus; 2) apoptosis - OHCs were shrunken & dark-staining with a pyknotic nucleus; & 3) a third death pathway - OHCs had no basolateral plasma membrane, a nucleus deficient in nucleoplasm & cellular debris arranged in the shape of an intact OHC. To minimize the secondary loss of OHCs that occurs post-exposure, the specimens used for quantitative analysis of death pathways had the following characteristics: a) the level to which they were exposed was < 95 dB SPL; b) the exposure duration was 6-216 h; c) the cochleae were fixed in-vivo 1-2 h post-exposure; & d) there were no focal OHC lesions in the OC. Fifty-eight noise-exposed cochleae in our collection met these criteria. The specimens had a variable amount of OHC loss, minimal IHC loss, rare pillar loss, & no spiral ganglion cell loss. The cochleae were grouped by total exposure energy [E = log2 (Pa2 seconds)] into 7 Groups with energies ranging from 7.77-17.74 for the 0.5-kHz OBN & 6 Groups with energies ranging from 5.11-14.75 for the 4- kHz OBN. In all specimens, degenerating & missing OHCs were classified as to which death pathway the cells were following. Nine non-noise-exposed cochleae were also evaluated for OHC death pathways. The number of OHCs following the third death pathway was significantly greater in the noise-exposed cochleae than the non-noise-exposed cochleae for total exposure energies greater than that produced by a 0.5-kHz OBN at 75 dB SPL for 216 h (i.e., 13.26) or a 4-kHz OBN at 57 dB SPL for 48 h (i.e., 5.11). In cochleae exposed to either octave band, OHCs dying by oncosis or apoptosis were uncommon. Further work must be done on cell-death pathways in the noise-damaged cochlea to determine how the prevalence of the different pathways changes with exposure parameters. [Description provided by NIOSH]
• Subjects:
  Animals Hearing Hearing Loss Hearing Loss, Noise-Induced Laboratories Noise Occupational Health Safety
• Keywords:
  Exposure-levels Hearing-disorders Hearing-loss Laboratory-animals Noise-exposure Noise-induced-hearing-loss
• ISSN:
  0742-3152
• Publisher:
  Association for Research in Otolaryngology
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  Arizona ; Missouri ; New York ; OSHA Region 2 ; OSHA Region 7 ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  30
• NIOSHTIC Number:
  nn:20041565
• Citation:
  Abstr Midwinter Res Meet Assoc Res Otolaryngol 2007 Feb; 30:113
• Editor(s):
  Santi PA
• Federal Fiscal Year:
  2007
• Performing Organization:
  Washington University, St. Louis
• Peer Reviewed:
  False
• Start Date:
  20000401
• Source Full Name:
  Abstracts of the 30th Midwinter Research Meeting of the Association for Research in Otolaryngology, Febuary 10-15, 2007, Denver, Colorado
• End Date:
  20130914
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:51539f40e54e207001576a52673718c0c72767bb1219e9e53b5ee04bb9b4c7ceee7b72918ac8667c26d2a4e63ff0f3c3d2171e249d3ec180a99ce69788b5a076
• Download URL:
  https://stacks.cdc.gov/view/cdc/194099/cdc_194099_DS1.pdf
• File Type:
  [PDF - 150.10 KB ]