The effects of kainic acid on the vestibular ganglion cells

The effects of intra-labyrinthine application of kainic acid on afferent vestibular nerve terminals and vestibular ganglion cells were investigated in this study. Results showed 10 nM kainic acid can induce scattered swelling of the calyx nerve endings surrounding type I vestibular hair cells. The swelling became much more severe when kainic acid concentration increased to 50 nM. The calyx swelling is also the earliest pathological change in the vestibular epithelium after a short period of anoxia. Degeneration of vestibular ganglion cells was found 1 week after kainic acid treatment. These results suggested, like in the cochlea, excitotoxicity can be mediated by overactivation of KA receptors. This is also an indirect evidence support L-glutamate as the neurotransmitter used in the peripheral afferent vestibular system.