The mouse is the most commonly used animal in biomedical research, because of recent advances in molecular genetic techniques. Studies related to eye movements in mice are common in the fields of ophthalmology, neuro-otology, and psychology. We developed a new system for analyzing the three-dimensional rotation vector of eye movements in mice using high-speed video-oculography. Using the eye movement analysis system, we were able to analyze the eye movements associated with the vestibulo-ocular reflex (VOR) and optokinetic stimulation in mice. In this review, we introduce studies that we performed using this system and have already been published and also introduce our future plan for studies to be performed using this system and are expected to contribute to the treatment of patients complaining of vertigo.
Unilateral vestibular dysfunction mice were characterized by spontaneous nystagmus in the direction of the healthy ear. In mice with bilateral vestibular dysfunction, VOR was not induced during rotation.
We investigated cisplatin-induced vestibulotoxicity in C57BL/6J mice. Cisplatin decreased the VOR gain at 2.5Hz as compared to that in the vehicle control. This mouse model may be useful for studying cisplatin-induced vestibulotoxicity and its treatment.
We assessed the physiological function of the P2X2 receptor in vivo using P2X2 receptor-knockout mice. We showed that the P2X2 receptors are mainly localized in the supporting cells of the vestibular inner ear, and that the loss of P2X2 receptors causes mild vestibular dysfunction, i.e., a significant decrease of the VOR gain. Taken together, our findings suggest that the P2X2 receptor plays a modulatory role in vestibular function.
In the future, we expect that a rationale for vestibular rehabilitation of patients with vertigo will be established by clarifying the mechanism of interaction between VOR and the optokinetic response.
