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

基本信息

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

项目摘要

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

这项研究旨在阐明通过刺激髓质网状形成（MRF）产生的广义运动抑制作用所涉及的脊柱间神经元机制。 Changes in the excitement 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在前骨上的水平。 MRF刺激在伸肌和屈肌MNS中诱导抑制性突触后电位（IPSP），以及屈肌MNS的后肢肌肉以及大多数介导的相互抑制作用，非接头I组I组抑制作用，经常性抑制作用，经常性抑制作用，以及弯曲反射反射（FRA）（FRA）。它还产生了IA，IB和皮肤传入纤维的初级传入（PAD）。 MNS和INS中的IPSP，以及……更多的主要传入中的更多垫子都被FRA中的Volleys抑制了。这些INS位于椎板VII的腹膜介导的部分中。尖峰触发的平均值表明，它们在MN和ins中产生了单突触IPSP，并在主要传入中产生了PAD。这些结果表明，普遍的运动抑制不仅是由于MNS的突触后抑制作用和在反射途径中插入的INS，而且还抑制了初级传播末端的兴奋。这种抑制作用可能是通过接收兴奋性MRF输入和抑制性FRA输入来介导的。结果还提出了髓质网途径和FRA途径之间脊柱间神经元水平的共抑制性相互作用。它可以用作功能门，该功能门会整合来自较高电机中心和外围感觉信号的降序信号以修改正在进行的运动。较少的