Consistent removal of hair cells in vestibular end organs by time-dependent transtympanic administration of gentamicin in guinea pigs

• Published in: Journal of neuroscience methods 2021-03, Vol.351, p.109049-109049, Article 109049
• Main Authors: Chiba, Makoto, Ito, Tsukasa, Shinkawa, Chikako, Koizumi, Yutaka, Hull, Melinda, Kakehata, Seiji
• Format: Article
• Language: English
• Subjects: Gentamicin; Transtympanic injection; Type I hair cells; Type II hair cells; Vestibular system
• ISSN: 0165-0270; 1872-678X
• DOI: 10.1016/j.jneumeth.2020.109049

•The vestibular system is a sensory system which plays a critical role in balance.•We developed a damage protocol to selectively target type I vestibular hair cells.•This novel protocol uses a timed transtympanic administration of gentamicin.•Uniform damage to vestibular function and hair cell loss were achieved.•This damage protocol can be used for research into vestibular balance disorders. Vestibular hair cell loss and its role in balance disorders are not yet completely understood due largely to the lack of precise hair cell damage protocols. Our damage protocol aims to selectively remove type I hair cells in a way that produces consistent and predictable lesions that can be used for reliable inter-animal and inter-group comparison in balance research. This objective is achieved by transtympanic injection of gentamicin on both the round window membrane and oval window over a fixed time period followed by thorough washing. We achieved nearly total and consistent loss of type I hair cells at 94 % for the crista ampullaris of the lateral semicircular canal (LSC) and 86 % for the utricular macula with negligible loss of type II hair cells at 4% for the crista ampullaris of the LSC and 6% for the utricular macula. While the vestibular function was compromised in the relevant study group, this group had a zero mortality rate with no significant suppression of body weight gain. Gentamicin is typically administered via intraperitoneal systemic injection or, more recently, transtympanic injection. The intraperitoneal method is simple, but mortality rate is high. The transtympanic injection method produces ototoxic damage but with inconsistent lesion size. This inconsistency prevents reliable comparisons among animals. This protocol employs a transtympanic injection method which selectively targets type I hair cells for removal in the vestibular epithelia in a time-dependent manner, uniformly damages vestibular function, and causes uniform hair cell loss.