An augmented acoustic environment delays age-related hearing loss in C57BL/6J mice as revealed by DPOAEs and cochlear histopathology

Details

• Personal Author:
  Bohne BA ; Candreia C ; Harding GW ; Lonsbury-Martin BL ; Martin GK ; Stagner BB
• Description:
  Willott and Turner (Hear Res, 1999) reported that an augmented acoustic environment (AAE) delayed age-related hearing loss (AHL) in C57BL/6J (C57) mice. The present study assessed cochlear function at the outer hair cell (OHC) level by measuring distortion-product otoacoustic emissions (DPOAEs) in both AAE and control mice. These results were subsequently correlated with cochlear histopathology. Beginning at 25 d of age, C57 mice were exposed nightly, for 12 h, to a 70-dB SPL broadband AAE (200-ms pulses at 2/s), centered at 10 kHz. DPOAEs were recorded in the form of DP-grams (DPOAE level as a function of primary-tone frequency), with geometric-mean (GM) frequencies ranging from 5.6-48.5 kHz (f2=6.3-54.2 kHz), in 0.1-oct steps. DP-grams were collected at three primary-tone levels (L1=L2=55, 65, 75 dB SPL). ABRs were recorded at 6, 8, 12, 16, 24, and 32 kHz to confirm the AAE effect. At 6 mo of age, both cochleas from 4 control and 3 AAE mice were post-fixed in OsO4, dehydrated, embedded in plastic and dissected as flat preparations. Hair-cell, supporting-cell and nerve-fiber losses were determined from apex to base and cytocochleograms prepared for all cochleas. Function-structure correlations were made by overlaying the final DP-gram on the cytocochleogram. By 4 mo of age, clear differences between AAE and control DPOAEs were observed. Control C57s showed average DPOAEs that were near noise-floor levels between GM frequencies of 25-48.5 kHz, while the AAE ears exhibited moderately reduced DPOAEs over a restricted range of GM frequencies between 25-35 kHz. The functional data matched well with the histopathology in all ears. As a group, the controls had worse function and more hair-cell loss than the AAE mice. However, in both groups, there was large variability across mice. The ears of the AAE mice were more variable than the controls and 2/3 had pronounced asymmetries between ears. [Description provided by NIOSH]
• Subjects:
  Aging Animals Hearing Hearing Loss Hearing Loss, Noise-Induced Laboratories Noise Occupational Health Safety
• Keywords:
  Age-groups Animal-studies Cell-damage Cellular-reactions Exposure-levels Hearing-disorders Hearing-loss Histopathology Laboratory-animals Nerve-damage Nerve-fibers Noise-exposure Noise-induced-hearing-loss

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• ISSN:
  0742-3152
• Publisher:
  Association for Research in Otolaryngology
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Abstract or Summary
• Place as Subject:
  Colorado ; Florida ; Missouri ; New Jersey ; OSHA Region 2 ; OSHA Region 4 ; OSHA Region 7 ; OSHA Region 8
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  69-70
• Volume:
  25
• NIOSHTIC Number:
  nn:20041609
• Citation:
  Abstr Midwinter Res Meet Assoc Res Otolaryngol 2002 Jan; 27:69-70
• Editor(s):
  Santi PA
• Federal Fiscal Year:
  2002
• Performing Organization:
  Washington University, St. Louis
• Peer Reviewed:
  False
• Start Date:
  20000401
• Source Full Name:
  Abstracts of the 25th Midwinter Research Meeting of the Association for Research in Otolaryngology, January 27-31, 2002, St. Petersburg Beach, Florida
• End Date:
  20130914
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8ed60c781d779e215ad716cc59528bbd119dff9decb15d32b169fc9890fd7b920dda0167d898e8f5bbabb05ecaa47385aa4596b0625c552c2caf7243ae8b2028
• Download URL:
  https://stacks.cdc.gov/view/cdc/194123/cdc_194123_DS1.pdf
• File Type:
  [PDF - 179.01 KB ]