Maroto Alberto F, Barrallo-Gimeno Alejandro, Llorens Jordi
Departament de Ciències Fisiològiques, Institut de Neurociènces, Universitat de Barcelona, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Catalunya, Spain.
Departament de Ciències Fisiològiques, Institut de Neurociènces, Universitat de Barcelona, Feixa Llarga s/n, 08907 L'Hospitalet de Llobregat, Catalunya, Spain; Institut d'Investigació Biomèdica de Bellvitge, IDIBELL, 08907 L'Hospitalet de Llobregat, Catalunya, Spain.
Hear Res. 2021 Oct;410:108336. doi: 10.1016/j.heares.2021.108336. Epub 2021 Aug 24.
The tail-lift reflex and the air-righting reflex in rats are anti-gravity reflexes that depend on vestibular function. To begin identifying their cellular basis, this study examined the relationship between reflex loss and the graded lesions caused in the vestibular sensory epithelia by varying doses of an ototoxic compound. After ototoxic exposure, we recorded these reflexes using high speed video. The movies were used to obtain objective measures of the reflexes: the minimum angle formed by the nose, the back of the neck and the base of the tail during the tail-lift maneuver and the time to right in the air-righting test. The vestibular sensory epithelia were then collected from the rats and used to estimate the loss of type I (HCI), type II (HCII) and all hair cells (HC) in both central and peripheral parts of the crista, utricle, and saccule. As expected, tail-lift angles decreased, and air-righting times increased, while the numbers of HCs remaining in the epithelia decreased in a dose-dependent manner. The results demonstrated greater sensitivity of HCI compared to HCII to the IDPN ototoxicity, as well as a relative resiliency of the saccule compared to the crista and utricle. Comparing the functional measures with the cell counts, we observed that loss of the tail-lift reflex associates better with HCI than with HCII loss. In contrast, most HCI in the crista and utricle were lost before air-righting times increased. These data suggest that these reflexes depend on the function of non-identical populations of vestibular HCs.
大鼠的尾举反射和空中翻正反射是依赖前庭功能的抗重力反射。为了开始确定它们的细胞基础，本研究检查了反射丧失与不同剂量耳毒性化合物在前庭感觉上皮中引起的分级损伤之间的关系。耳毒性暴露后，我们使用高速视频记录这些反射。这些视频用于获得反射的客观测量值：尾举动作期间鼻子、颈部后部和尾巴基部形成的最小角度，以及空中翻正测试中的翻正时间。然后从大鼠中收集前庭感觉上皮，用于估计嵴、椭圆囊和球囊中央和外周部分的I型（HCI）、II型（HCII）和所有毛细胞（HC）的损失。正如预期的那样，尾举角度减小，空中翻正时间增加，而上皮中剩余的毛细胞数量呈剂量依赖性减少。结果表明，与HCII相比，HCI对IDPN耳毒性更敏感，并且与嵴和椭圆囊相比，球囊具有相对的弹性。将功能测量结果与细胞计数进行比较，我们观察到尾举反射的丧失与HCI丧失的相关性比与HCII丧失的相关性更好。相反，在嵴和椭圆囊中，大多数HCI在翻正时间增加之前就已经丧失。这些数据表明，这些反射依赖于不同群体的前庭毛细胞的功能。
