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In Vitro Wedge Slice Preparation for Mimicking In Vivo Neuronal Circuit Connectivity
Published on: August 18, 2020
Neuronal circuits involved in the middle-ear acoustic reflex
Thomas Venet1, Cécile Rumeau, Pierre Campo
1Institut National de Recherche et de Sécurité, Rue du Morvan, CS 60027, 54519 Vandœuvre Cédex, France.
Summary
Toluene exposure can alter middle-ear acoustic reflex efficiency in rats, potentially explaining how aromatic solvents worsen noise-induced hearing loss. Further research proposed a new neuronal circuit for this reflex.
Area of Science:
- Neuroscience
- Audiology
- Toxicology
Background:
- Aromatic solvents like toluene are known to cause hearing loss.
- Toluene may worsen noise-induced hearing loss by affecting the middle-ear acoustic reflex.
- The precise mechanism of toluene's impact on auditory function requires further investigation.
Purpose of the Study:
- To investigate the physiological effects of toluene on the middle-ear acoustic reflex in Long-Evans rats.
- To determine how different toluene concentrations influence the middle-ear acoustic reflex efficiency.
- To explore the role of central auditory nuclei in toluene's effects on hearing.
Main Methods:
- Auditory function was assessed using distortion otoacoustic emissions (2f1 - f2) in rats.
- The middle-ear acoustic reflex was activated and modulated using contralateral or ipsilateral noise suppressors.
- Toluene was administered via carotid artery injection at varying concentrations (58.4, 87.4, 116.2mM).
Main Results:
- Toluene administration resulted in dose-dependent changes in middle-ear acoustic reflex efficiency, with effects varying based on concentration and noise suppressor application.
- Toluene was observed to either enhance or impair the reflex, indicating a complex interaction.
- Findings suggest toluene impacts the central auditory pathways controlling the reflex.
Conclusions:
- Toluene exposure can significantly alter middle-ear acoustic reflex efficiency in a concentration-dependent manner.
- A novel neuronal circuit for the middle-ear acoustic reflex has been proposed based on the study's findings.
- The inhibitory effects of toluene on central auditory nuclei may underlie the synergistic hearing damage observed with combined noise and solvent exposure.
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