An In Vivo Tracer Study of Noise-Induced Damage to the Reticular Lamina

Details

• Personal Author:
  Ahmad M ; Bohne BA ; Harding GW
• Description:
  An in vivo tracer was used to determine if the reticular lamina and/or the cell membranes abutting the endolymphatic space are temporarily disrupted after intense noise exposure (4-kHz OBN, 108-dB SPL, 1.75 h). Using a double-barreled micropipette, the endolymphatic potential (EP) was recorded and artificial endolymph containing 10% carbon particles was injected into the endolymphatic space either 0 days or 28 days post-exposure. The cochleae were fixed 30-45 min post-injection, then dehydrated, embedded in plastic and dissected as flat preparations. Damage in the organ of Corti (OC) was quantified, the location of carbon was determined, and some OC segments were then sectioned radially. EP averaged 72+/-5 mV in five controls. These cochleae had carbon tracer in the endolymphatic space only. Four of five noise-exposed chinchillas examined 3-4 h post-exposure had a low EP (30+/-6 mV). The cochleae from these 0-day animals had several focal lesions in which nearly all outer hair cells had just degenerated. At these lesions, carbon was attached to cell membranes and debris between the reticular lamina and basilar membrane. By transmission electron microscopy, discontinuities were found in the apical membranes of sensory and supporting cells. Carbon particles were found in the cytoplasm of these cells. Four of five animals examined at 28 days had an average EP of 70+/-11 mV. The cochleae from these animals had multiple lesions in the basal turn, all of which were healed by phalangeal scars or squamous epithelial cells. In these cochleae, no carbon was found within the OC. Acute disruption of the reticular lamina and the apical membranes of sensory and supporting cells from noise appears to be a major mechanism to account for degeneration in the cochlea that spreads or continues for days to weeks post-exposure. [Description provided by NIOSH]
• Subjects:
  Animals Environmental Monitoring Laboratories Noise Occupational Health Safety
• Keywords:
  Animal-studies Exposure-assessment Exposure-levels In-vivo-studies In-vivo-study Laboratory-animals Noise-exposure
• ISSN:
  0378-5955
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Missouri ; OSHA Region 7
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  82-100
• Volume:
  175
• Issue:
  1
• NIOSHTIC Number:
  nn:20029133
• Citation:
  Hear Res 2003 Jan; 175(1-2):82-100
• Contact Point Address:
  Washington University School of Medicine, Department of Otolaryngology, Box 8115, 660 South Euclid Avenue, St Louis, MO 63110, USA
• Email:
  bohneb@msnotes.wustl.edu
• Federal Fiscal Year:
  2003
• NORA Priority Area:
  Disease and Injury: Hearing Loss
• Performing Organization:
  Washington University, St. Louis
• Peer Reviewed:
  True
• Start Date:
  20000401
• Source Full Name:
  Hearing Research
• End Date:
  20130914
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:9e56e09dca3aa2c52859569cefdd103028f64a25210991c3c04fc7208d46fd080a8c189a86de041de467cfd4de1ebb0e3741ccfaf61949e17cb291a7f1d3ade8
• Download URL:
  https://stacks.cdc.gov/view/cdc/190185/cdc_190185_DS1.pdf
• File Type:
  [PDF - 1.56 MB ]