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Succinate dehydrogenase (SDH) activity in hair cells: a correlate for permanent threshold elevations.

Authors
Chen-GD; McWilliams-ML; Fechter-LD
Source
Hear Res 2000 Jul; 145(1-2):91-100
NIOSHTIC No.
20029810
Abstract
Hair cell loss is often used as a histological correlate of hearing loss. However, the histological and the physiological data are not always well correlated. This paper investigates the use of succinate dehydrogenase (SDH) activity in the hair cells as a marker of cellular dysfunction and so the loss of auditory sensitivity. In our previous studies, potentiation of noise-induced auditory threshold elevation by carbon monoxide (CO) was observed [Chen and Fechter, 1999; Chen et al., 1999]. However, its histological basis is still unclear. In this study, rats were exposed to 100-dB octave-band noise (center frequency=13.6 kHz, 2 h) or to the combination of the noise and CO (1200 ppm). Threshold elevation of compound action potential (CAP) and cochlear histological changes were assessed 4 weeks after exposure. The noise alone caused CAP threshold elevations with little if any or without hair cell loss. However, the SDH activity in the hair cells decreased after the exposure. The SDH reduction, especially in the inner hair cells, was well related to the loss of auditory sensitivity. The combined exposure to noise and CO caused more severe CAP threshold elevation and SDH activity reduction than did the noise alone and it also caused significant outer hair cell loss. However, across all the test frequencies, neither the hair cell loss nor the SDH reduction alone had good correlation to the reduction of the auditory sensitivity. Under this situation, CAP threshold elevation seemed to follow OHC loss at high frequencies and to follow SDH reductions in the IHCs at low frequencies, where no hair cell loss occurred.
Keywords
Hearing-protection; Noise-induced-hearing-loss; Synergistic-effects; Organic-solvents; Ototoxicity; Hearing; Hearing-impairment; Hearing-level; Hearing-loss; Hearing-tests; Hearing-threshold; Cellular-structures; Cell-metabolism
Contact
University of Oklahoma, Health Sciences Center, College of Pharmacy, P.O. Box 26901, 1110 N. Stonewall, Oklahoma City, OK 73190
CODEN
HERED3
CAS No.
630-08-0; 57-12-5
Publication Date
20000701
Document Type
Journal Article
Email Address
guangdi-chen@ouhsc.edu
Funding Amount
561752
Funding Type
Grant
Fiscal Year
2000
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-003481
Issue of Publication
1-2
ISSN
0378-5955
Priority Area
Disease and Injury: Hearing Loss
Source Name
Hearing Research
State
OK
Performing Organization
University of Oklahoma, Health Sciences Center, Oklahoma Center for Toxicology, Oklahoma City, Oklahoma
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