Furuya N, Koizumi T
Department of Otolaryngology, Teikyo University School of Medicine, Ichihara Hospital, Chiba, Japan.
Acta Otolaryngol. 1998 Jan;118(1):64-9. doi: 10.1080/00016489850155143.
The present study examined transmitters that regulate commissural inhibition. Extracellular spikes of a single vestibular neuron were recorded in decerebrated cats. Multibarreled electrodes were filled with transmitter candidates (GABA and glycine), their specific antagonists (bicuculline, strychnine) and 2 M NaCl for extracellular recording. After isolation of a type I neuron, chemicals were iontophoretically applied to examine their effects on the activity of the neuron. The results were as follows. Commissural inhibition caused by electrical stimulation of the contralateral labyrinth was not abolished by the application of strychnine (a glycine antagonist), but was abolished by bicuculline (a GABA antagonist). Commissural inhibition was not abolished by phaclofen. Some bicuculline-sensitive neurons, with a short-latency commissural inhibition (presumably disynaptic inhibition), showed spacial summation when the conditioning stimulation (contralateral vestibular nerve stimulation) was applied with the test stimulation (vestibular nucleus stimulation). It was concluded that commissural inhibition was activated by the GABAA receptor, but not by the GABAB receptor, that the inhibitory type I neurons located in the contralateral vestibular nucleus were GABAergic, and that inhibitory type II neurons were also GABAergic neurons.
本研究检测了调节连合抑制的递质。在去大脑猫中记录单个前庭神经元的细胞外锋电位。多管电极分别充以递质候选物（γ-氨基丁酸和甘氨酸）、它们的特异性拮抗剂（荷包牡丹碱、士的宁）以及用于细胞外记录的2M氯化钠。分离出I型神经元后，通过离子电泳施加化学物质以检测它们对神经元活动的影响。结果如下。对侧迷路电刺激所引起的连合抑制，在应用士的宁（一种甘氨酸拮抗剂）后并未消除，但在应用荷包牡丹碱（一种γ-氨基丁酸拮抗剂）后被消除。巴氯芬并未消除连合抑制。一些对荷包牡丹碱敏感的神经元，具有短潜伏期的连合抑制（推测为双突触抑制），当条件刺激（对侧前庭神经刺激）与测试刺激（前庭核刺激）同时施加时，表现出空间总和。得出的结论是，连合抑制由GABAA受体激活，而非由GABAB受体激活，位于对侧前庭核的抑制性I型神经元是γ-氨基丁酸能的，并且抑制性II型神经元也是γ-氨基丁酸能神经元。
