Role of inferior colliculus in vestibular vertigo induced by water caloric irrigation

Abstract

Background: Vestibular vertigo is a common clinical symptom; however, the central neural mechanism of it is still poorly understood.Objective: To demonstrate the changes of neural excitability and ascorbate in inferior colliculus (IC) in a rat vertigo model induced by water caloric irrigation.Methods: In vertigo model induced by water caloric irrigation, we recorded the changes of spontaneous firing rate (SFR) of IC. Then a technique that combining in vivo microanalysis with an online electrochemical system (OECS) was employed to monitor the changes of extracellular ascorbate in IC.Results: Electrophysiological studies showed that after vestibular ice water stimulation, the level of SFR in IC significantly increased, reaching (989 ± 9) % and (941 ± 62) % respectively at 2.0 h after contralateral ice water vestibular stimulation and ipsilateral ice water vestibular stimulation. However, the level of ascorbate in IC dramatically decreased after ice stimulation, decreased to (30 ± 12) % and (57 ± 24) % of the basal level respectively in the contralateral group and ipsilateral group.Conclusions and significance: These findings suggest that inferior colliculus plays a role in peripheral vertigo, which would appear useful for uncovering neural mechanisms of vertigo and help finding novel therapeutic targets for vertigo.