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Published on: November 26, 2015
[Morphological observations of the medial olivocochlear efferents in gerbils with chronic gentamicin ototoxicity]
1Department of Otorhinolaryngology, Second Affiliated Hospital of Hunan Medical University, Changsha 410011.
Objective:
To determine the possible involvement of the medial olivocochlear efferents (MOC) in chronic aminoglycoside ototoxicity, the morphological changes of the MOC efferents in the cochlea of Mongolian gerbils and their correlations with the impairment of the outer hair cells (OHCs) were observed.
Methods:
The animals were given gentamicin in a dose of 150 mg/kg a day for 10 days. The distributions and densities of the MOC efferents were examined using the modified histochemical staining for acetylcholinesterase (AChE) and the numbers of OHCs were numerated with toluidine blue and Ehrlich haematoxylin staining on the surface preparation.
Results:
Significant damage to the MOC fibers and terminals as well as OHCs was noted in the basal turn of the cochlea, especially in those animals examined in 7th and 11th week after the gentamicin administration. The site of the greatest impairment of OHCs was consistent with that of the MOC efferents.
Conclusion:
The results suggested that damage to the MOC efferents might play an important role in gentamicin-induced impairment of OHCs.
Insights
Damage to medial olivocochlear efferents (MOC) may contribute to gentamicin-induced hearing loss. This study observed MOC fiber and outer hair cell (OHC) damage in gerbils after gentamicin exposure.
Area of Science:
- Neuroscience
- Ototoxicology
- Auditory Neuroscience
Context:
- Aminoglycoside antibiotics, like gentamicin, are widely used but can cause ototoxicity.
- The medial olivocochlear efferents (MOC) are neural pathways that modulate cochlear function.
- The role of MOC in aminoglycoside-induced hearing damage remains unclear.
Purpose:
- To investigate the potential involvement of MOC in chronic aminoglycoside ototoxicity.
- To examine morphological changes in MOC efferents and their correlation with outer hair cell (OHC) impairment in gerbils exposed to gentamicin.
Summary:
- Mongolian gerbils received daily gentamicin injections (150 mg/kg) for 10 days.
- MOC efferents were analyzed using acetylcholinesterase (AChE) staining.
- OHC numbers were quantified using toluidine blue and Ehrlich haematoxylin staining.
Impact:
- Significant damage to MOC fibers and OHCs was observed in the basal cochlear turn, particularly by the 7th and 11th weeks post-gentamicin administration.
- The areas of greatest OHC impairment coincided with the areas of MOC efferent damage.
- These findings suggest that MOC efferent damage may play a crucial role in gentamicin-induced OHC impairment and subsequent hearing loss.
