Damage to Vestibular Ganglion Cells of Guinea Pigs by Gentamicin

Abstract

Morphological changes were induced in vestibular ganglion cells by gentamicin or labyrinthectomy and examined by transmission electron microscopy. Gentamicin (250mg/kg) was administered via the carotid artery.
By 24 hours after the injection, the vestibular sensory cilia had almost disappeared. Seven days after the injection, no significant change was observed in the vestibular sensory cilia. However, the number of neurofilaments in the vestibular ganglion cells was increased, and the endoplasmic reticulum had been transformed morphologically to polysomes.
Cytochemical stains showed that acid phosphatese (ACPase) activity and cytochrome oxidase activity had decreased.
On the other hand, 7 days after labyrinthectomy, no significant change was observed in the vestibular ganglion cells either morphologically or cytochemically. After one month, however, vacuoles had formed and cytochrome oxidase activity was decreased.
These results suggest that the early effect of gentamicin on the vestibular ganglion cells is reversible and may be due to direct action of gentamicin. This early change is followed by irreversible retrograde action which finally leads to cell degeneration.