Chinchilla models of selective cochlear hair cell loss
Although it is well known that ethacrynic acid (EA) can enhance gentamicin (GM) ototoxicity, there has been no systematic study of the relationship between dosing parameters and inner ear pathology. We examined the effects of two parameters, GM dose and time delay between GM and EA administration, o...
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Published in | Hearing research Vol. 174; no. 1; pp. 230 - 238 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Amsterdam
Elsevier B.V
01.12.2002
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | Although it is well known that ethacrynic acid (EA) can enhance gentamicin (GM) ototoxicity, there has been no systematic study of the relationship between dosing parameters and inner ear pathology. We examined the effects of two parameters, GM dose and time delay between GM and EA administration, on cochlear and vestibular hair cell loss in chinchillas. ‘No delay’ groups received one injection of GM (125, 40, 20, or 10 mg/kg i.m.) followed immediately by EA (40 mg/kg i.v.); ‘delay’ groups received GM (10 mg/kg i.m.) followed by EA 1 or 1.5 h later. Animals were sacrificed 7 days later for evaluation of hair cell loss in the cochlea and vestibular end organs (cristae, saccule and utricle). Vestibular function was assessed prior to sacrifice by measuring the duration of nystagmus induced by cold caloric stimulation. No delay groups had ∼100% loss of outer hair cells and dose-dependent losses of inner hair cells, ranging from ∼100% to 58%. In 1 and 1.5 h delay groups, inner hair cell losses were ∼19% and 0%, outer hair cell losses were ∼74% and 47%, and outer hair cell loss followed a typical base to apex gradient. Two results were remarkable. First, the three groups with partial inner hair cell loss showed an atypical lesion pattern in which losses were substantially greater in the apical half than in the basal half of the cochlea. Second, there was no vestibular pathology in any group. The results establish dosing parameters that can be used to produce animal models with defined patterns and magnitudes of cochlear hair cell damage, but normal vestibular function and morphology. |
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ISSN: | 0378-5955 1878-5891 |
DOI: | 10.1016/S0378-5955(02)00697-4 |