Synaptic and molecular mechanisms that control the excitability of spinal interneurons

控制脊髓中间神经元兴奋性的突触和分子机制

• 批准号: 08680877
• 负责人: TAKAKUSAKI Kaoru
• 金额: $ 1.6万
• 依托单位: Asahikawa Medical College
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08680877/
• 关键词: Postural muscle tone; Generalized Motor Inhibition; Spinal interneurons; Flexor reflex afferents; Postsynaptic inhibition; Presynaptic inhibition; Ca channel; Rhythmic firing; シナプス機構; 分子機構; リズム発生機序; 歩行運動

This study was aimed at elucidating the spinal interneuronal mechanisms involved in the generalized motor inhibition produced by stimulating the medullary reticular formation (MRF). Changes in the excitability of hindlimb alpha-motoneurons (MNs), interneuronal transmission of reflex pathways to MNs, interneurons (INs) in reflex pathways and primary afferent terminals in lumbosacral segments (L5-S1) were examined before and after the MRF stimulations in acute decerebrate cats.Seventy-six cats weighing of 2.1-4.3 kg were decerebrated at precollicular-postmammilarly level. The MRF stimulation induced inhibitory postsynaptic potentials (IPSPs) in both extensor and flexor MNs innervating hindlimb muscles as well as most INs mediating reciprocal Ia inhibition, non-reciprocal group I inhibition, recurrent inhibition, and flexor reflex afferent (FRA) pathways. It also produced primary afferent depolarization (PAD) of Ia, Ib and cutaneous afferent fibers. Both the IPSPs in MNs and INs, and the … More PAD in primary afferents were suppressed by volleys in FRA.However, the MRF stimulation excited INs that received inhibition from FRA.One-fourth of them also received monosynaptic excitation from group I afferent. These INs were located in ventro-medial portion of lamina VII.Spike-triggered averaging revealed that they produced monosynaptic IPSPs in MNs as well as INs, and produced PAD in primary afferents.These results suggest that the generalized motor inhibition is due to not only the postsynaptic inhibition of MNs and INs interposed in reflex pathways but also suppression of excitability of primary afferent terminals. Such inhibitory effects are possibly mediated by INs receiving excitatory MRF input and inhibitory FRA input. The results also proposed the co-inhibitory interaction at spinal interneuronal level between the medullary reticulospinal pathway and FRA pathways. It may operate as a functional gate that integrate descending signals from higher motor centers and peripheral sensory signals to modify ongoing movements. Less

本研究旨在阐明通过刺激髓网状结构（MRF）产生的广泛性运动抑制的脊髓神经元间机制。研究了急性失觉猫在MRF刺激前后后肢α -运动神经元（MNs）兴奋性、反射通路到MNs的神经元间传递、反射通路中间神经元（INs）和腰骶节（L5-S1）初级传入终端的变化。76只体重2.1-4.3 kg的猫在颈前-哺乳后水平进行了实验。MRF刺激在支配后肢肌肉的伸肌和屈肌MNs以及大多数介导Ia互反抑制、非互反I组抑制、复发抑制和屈肌反射传入（FRA）通路中诱导抑制性突触后电位（IPSPs）。它还产生了Ia、Ib和皮肤传入纤维的初级传入去极化（PAD）。MNs和INs的ipsp以及原发事件中更多的PAD均被FRA的齐射抑制。然而，MRF刺激激发了受到FRA抑制的INs。其中四分之一的小鼠也接受了来自第一组传入的单突触兴奋。这些INs位于第七层的腹内侧部分。峰触发平均显示它们在MNs和INs中产生单突触ipsp，并在初级传入事件中产生PAD。这些结果表明，广泛性运动抑制不仅是由于在反射通路中插入的MNs和INs的突触后抑制，而且还包括初级传入终端兴奋性的抑制。这种抑制作用可能是由INs接受兴奋性MRF输入和抑制性FRA输入介导的。结果还提出了脊髓神经元间水平的脊髓网状通路和FRA通路之间的共抑制相互作用。它可以作为一个功能门，整合来自高级运动中心的下行信号和外围感觉信号来修改正在进行的运动。少

项目成果

高草木 薫: "脚橋被蓋核と運動の制御" 精神神経薬理. 19. 349-356 (1997)

Kaoru Takakusagi：“脚桥被盖核和运动控制”精神神经药理学 19. 349-356 (1997)

Takakusaki K., Kagokawa H., and Sakamoto T.: "Reticulospinal suppression of postural muscle tone : Mechanisms of presynaptic inhibition." Japanese Journal of Physiology. 47 (Supplement 2). 479 (1997)

Takakusaki K.、Kagokawa H. 和 Sakamoto T.：“姿势肌张力的网状脊髓抑制：突触前抑制机制”。

Takakusaki K.: "The pedunculopontine tegmental nucleus and its role in motor control" Japanese Journal of Neurophamacology. 19 (5). 349-356 (1997)

Takakusaki K.：“脚桥被盖核及其在运动控制中的作用”日本神经药物学杂志。

Takakusaki K.et al.: "Reticulospinal suppression of postural muscle tone:mechanisms of………" Japanese Journal of Physiology(Supplement). 47. S479 (1997)

Takakusaki K.等人：“姿势肌张力的网状脊髓抑制：……的机制”日本生理学杂志（增刊）47.S479（1997）。

Takakusaki K.et al.: "Stimulus effects of the pedunculopontine tegmental nucleus (PPN) on…" Society for Neurocience abstract. 23. 762 (1997)

Takakusaki K. 等人：“脚桥被盖核 (PPN) 对……的刺激作用”神经科学学会摘要 23. 762 (1997)。