Pharmacological profile of vestibular inhibitory inputs to superior oblique motoneurons
Pharmacological profile of vestibular inhibitory inputs to superior oblique motoneurons
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DOI：
10.1007/s00415-018-8829-4
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发表时间：
2018-10-01
影响因子：
6
通讯作者：
Straka, Hans
中科院分区：
文献类型：
--
作者：
Soupiadou, Parthena;Branoner, Francisco;Straka, Hans
前庭-眼反射（Vestibulo-ocular reflexes，VOR）是由脑干三神经元通路介导的，它将半规管和耳石的感觉信号转化为运动指令，使特定空间的眼肌群收缩。前庭的兴奋和抑制的眼外运动神经元的基础上，这种反射是有序组织，并允许协调激活特定的眼肌和并发的放松，他们的拮抗对手。在这里，我们证明了在孤立的非洲爪蟾蝌蚪，上级斜运动神经元的放电调制周期性头部运动来自于交替的兴奋和抑制。后一种成分是由GABA介导的，与外直肌运动神经元中的甘氨酸能抑制成分不同。抑制的不同药理学特征与前庭眼投射神经元的菱形特异性起源以及GABA能和甘氨酸能前庭神经元的互补节段丰度相关。进化保守的菱形地形的前庭眼的预测使得它可能是一个类似的药理组织的抑制性VOR神经元在这里报道的无尾两栖动物也实施在哺乳动物物种，包括人类。
Vestibulo-ocular reflexes (VOR) are mediated by three-neuronal brainstem pathways that transform semicircular canal and otolith sensory signals into motor commands for the contraction of spatially specific sets of eye muscles. The vestibular excitation and inhibition of extraocular motoneurons underlying this reflex is reciprocally organized and allows coordinated activation of particular eye muscles and concurrent relaxation of their antagonistic counterparts. Here, we demonstrate in isolated preparations of Xenopus laevis tadpoles that the discharge modulation of superior oblique motoneurons during cyclic head motion derives from an alternating excitation and inhibition. The latter component is mediated exclusively by GABA, at variance with the glycinergic inhibitory component in lateral rectus motoneurons. The different pharmacological profile of the inhibition correlates with rhombomere-specific origins of vestibulo-ocular projection neurons and the complementary segmental abundance of GABAergic and glycinergic vestibular neurons. The evolutionary conserved rhombomeric topography of vestibulo-ocular projections makes it likely that a similar pharmacological organization of inhibitory VOR neurons as reported here for anurans is also implemented in mammalian species including humans.