Related Experiment Videos
Damage and threshold shift resulting from cochlear exposure to paraquat-generated superoxide.
Eric C Bielefeld1, Bo Hua Hu, Kelly Carney Harris
1Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, State University of New York at Buffalo, 137 Cary Hall, 3435 Main Street, Buffalo, NY 14214, USA. ecb2@buffalo.edu
Hearing Research
|June 7, 2005
Summary
Paraquat (PQ) exposure damages the cochlea by generating superoxide, leading to hearing loss and hair cell damage in a dose-dependent manner. These findings suggest superoxide pathways may link PQ ototoxicity to noise-induced hearing loss.
Area of Science:
- Oto-toxicology
- Auditory Neuroscience
- Biochemistry
Background:
- Superoxide is implicated in cochlear damage from noise and ototoxic drugs.
- NADPH oxidase-dependent superoxide generation contributes to cellular injury.
Purpose of the Study:
- To investigate the ototoxic effects of paraquat (PQ), a superoxide-generating herbicide, on the cochlea.
- To examine the impact of PQ on auditory evoked potential (AEP) thresholds and hair cell integrity.
Main Methods:
- Chinchillas were administered PQ via the round window at varying concentrations (10, 5, 3 mM, and vehicle control).
- Inferior colliculus (IC) evoked potential (EVP) thresholds were measured using implanted electrodes before and after PQ exposure.
- Hair cell damage was assessed post-exposure.
Main Results:
- PQ exposure caused a dose-dependent increase in IC EVP thresholds, peaking between 1-7 days post-exposure.
- Permanent threshold shift (PTS) was observed by Day 22, consistent with outer and inner hair cell loss.
- PQ-induced ototoxicity demonstrated similarities to noise-induced hearing loss.
Conclusions:
- NADPH oxidase-dependent superoxide generation via PQ causes cochlear pathology and hearing loss.
- The findings suggest shared biochemical pathways involving superoxide in PQ ototoxicity and noise-induced hearing loss.
- Superoxide may be a critical mediator in various forms of cochlear injury.