An integrated system for comprehensive mouse peripheral vestibular function evaluation based on Vestibulo-ocular Reflex

Abstract

In the realms of both vestibular and auditory research, conducting vestibular function tests is essential. However, unlike the auditory function tests which utilize standard equipment such as the Auditory Brainstem Response (ABR) device, there is no equivalent widely adopted apparatus for vestibular tests. This is largely due to the intricate nature of the vestibular system and the challenges associated with assessing its functions. Vestibulo-ocular reflexes (VORs) are the compensatory ocular reflexes that ensure stable vision during head motion. VORs are widely used in clinics for diagnosing the vestibular deficit. In the research field, VORs, including angular VOR (aVOR) or off-vertical axis rotation (OVAR) tests, have been used by various groups to evaluate the mouse vestibular function. However, the effectiveness of VOR tests has not been systematically evaluated with proper animal models, and the lack of commercial equipment hampers its accessibility, confining vestibular testing to a select few labs. In this study, we developed an integrated instrument system with both aVOR and OVAR modes for evaluating mouse vestibular function. To demonstrate its efficacy, peripheral vestibular animal models, 1) Vestibulotoxicity drugs 3,3-iminodiproprionitrile (IDPN, 2 mg/g and 4 mg/g) induced; 2) Critical MET-related mutant (Cdh23v2J/v2J and TMC1-/-); 3) Vestibulo-specific mutant (Zpld1-/- for semicircular canal dysfunction and Otop1tlt/tlt for otoconia deficient; 4) Unilateral vestibular lesion (UVL) model by injecting gentamicin into horizontal semicircular canal, were constructed and evaluated with the system. The results showed 1) Quantification of the vestibular deficit is achieved in a daily manner; 2) Both the otolith organ and semicircular canals can be assessed respectively; and 3) The lesion side of UVL can be identified. During an 8-week study of IDPN vestibulotoxicity, the vestibular function of 3 groups of 20 animals was evaluated at 15 test days. These test results reveal the potential of our system as a standard system for evaluating common vestibular deficits in mice.