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.

Chinese abstract

背景：前庭性眩晕是一种常见的临床症状。然而, 关于它的中枢神经机制, 我们仍知之甚少。

目的：探讨水热灌注引起的大鼠眩晕模型的神经兴奋性和下丘脑（IC）抗坏血酸的变化。

方法：在水热灌注引起的眩晕模型中, 记录IC的自发放电速率（SFR）的变化。然后, 将体内微分析与在线电化系统（OECS）相结合的技术用于监测IC中细胞外抗坏血酸的变化。

结果：电生理研究表明, 前庭冰水刺激后, 其IC中的SFR水平显著增加, 在对侧冰水前庭刺激和同侧冰水前庭刺激两小时后分别达到（989±9）％和（941±62）％。然而, 冰刺激后, IC中的抗坏血酸水平显著下降, 对侧组和同侧组分别降至基础水平的（30±12）％和（57±24）％。

结论和意义：这些发现表明下丘脑对外周眩晕起着一定作用, 这将有用于揭示眩晕的神经机制和帮助发现眩晕的新型治疗靶。

Keywords:

• Vestibular vertigo
• inferior colliculus
• neural activity
• ascorbate

Acknowledgments

The experiments were completed in Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, the Chinese Academy of Sciences. All the authors would like to thank Lanqun Mao for his technical assistance. We also thank our family members who participated in this study and thank for the support from National Natural Science Foundation of China.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [Grant No. 81870727, 21790391 for F. Ma, 81500783 for Y. Xin]; Key Clinical Project of Peking University Third Hospital [Grant No. BYSY2017025].