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Effect of gentamicin on vestibular ganglion
1Department of Otolaryngology, Hiroshima University School of Medicine, Japan.
Abstract:
The morphological changes of the vestibular ganglion induced by gentamicin (GM) were investigated using light, scanning and transmission electron microscopy. The guinea pigs were injected 4 mg of GM into the middle ear for 5 days. The vestibular ganglion was observed up to 4 weeks after the treatment. Three days after the treatment the degenerative change was first noted in the vestibular ganglion. The degenerative process started from the destruction of mitochondrial cristae and vacuolization of the cytoplasm of the Schwann cell. The cytoplasmic organelles in the ganglion cell gradually deteriorated with swelling of the endoplasmic cisterns as well as Golgi apparatus. At the later stage, the myelin sheath around the ganglion cell disappeared and the number of the cells reduced. These changes of the ganglion cell may be due to the direct action of GM.
Insights
Gentamicin (GM) causes vestibular ganglion damage in guinea pigs, starting with Schwann cell changes and progressing to ganglion cell deterioration and myelin sheath loss. These findings suggest a direct toxic effect of GM on the vestibular system.
Area of Science:
- Ototoxicity and Neurobiology
- Vestibular System Research
- Pharmacological Effects on Sensory Organs
Background:
- Gentamicin (GM) is an aminoglycoside antibiotic with known ototoxic potential.
- The vestibular ganglion is crucial for balance and spatial orientation.
- Understanding GM's impact on the vestibular ganglion is vital for managing side effects.
Purpose of the Study:
- To investigate the morphological changes in the vestibular ganglion induced by gentamicin exposure.
- To determine the timeline and progression of gentamicin-induced ototoxicity in the vestibular ganglion.
- To elucidate the cellular mechanisms underlying gentamicin's effects on vestibular ganglion cells.
Main Methods:
- Utilized light, scanning, and transmission electron microscopy for detailed morphological analysis.
- Administered gentamicin (4 mg) into the middle ear of guinea pigs for 5 consecutive days.
- Observed vestibular ganglion changes at various time points up to 4 weeks post-treatment.
Main Results:
- Degenerative changes in the vestibular ganglion were first observed 3 days after gentamicin treatment.
- Early changes included mitochondrial cristae destruction and Schwann cell cytoplasm vacuolization.
- Later stages showed deterioration of ganglion cell organelles, myelin sheath loss, and reduced cell numbers.
Conclusions:
- Gentamicin induces significant morphological damage to the vestibular ganglion in a time-dependent manner.
- The observed changes suggest a direct cytotoxic action of gentamicin on vestibular ganglion cells and associated Schwann cells.
- These findings contribute to understanding the mechanisms of gentamicin-induced vestibular dysfunction.