Absence of effects of contralateral group I muscle afferents on presynaptic inhibition of Ia terminals in humans and cats
Absence of effects of contralateral group I muscle afferents on presynaptic inhibition of Ia terminals in humans and cats
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DOI：
10.1152/jn.00831.2011
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发表时间：
2012-08-01
影响因子：
2.5
通讯作者：
Manjarrez, Elias
中科院分区：
文献类型：
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作者：
Mezzarane, Rinaldo Andre;Kohn, Andre Fabio;Manjarrez, Elias
Mezzarane RA，Kohn AF，Couto-Roldan E，Martinez L，弗洛雷斯A，Manjalez E.对侧I组肌肉传入对人和猫Ia终末突触前抑制的影响缺失。J Neurophysiol 108：1176-1185，2012.首次发表于2012年6月6日; doi：10.1152/jn.00831.2011.- I组传入神经对反射兴奋性的交叉影响及其作用机制尚未完全了解。目前的观点是，这种影响是微弱的，并通过寡突触途径间接发生。我们研究了可能的对侧影响，从组I传入突触前抑制Ia终端在人类和猫。在静息和坐姿的人类受试者中，通过对同侧腓总神经（CPN）的电刺激来条件化比目鱼肌（SO）H反射，以评估突触前抑制（PSI_control）的水平。对对侧小腿三头肌肌腱施加简短的条件振动刺激（以优先激活Ia肌传入）。将所得H反射反应（PSI_conditioned）的振幅与PSI_control下的H反射进行比较，即，没有振动。短暂的振动刺激和电击CPN之间的刺激间期为-60至60 ms。由两种刺激条件的H反射与仅由同侧CPN刺激条件的H反射没有区别。在麻醉猫上，同时记录左右L7前根的双侧单突触反射（MSRs）。在不同的时间间隔（0-120 ms）施加到对侧组I后二头肌和半腱肌（PBSt）传入的条件刺激对同侧腓肠肌/比目鱼肌（GS）MSR没有影响。还进行了使用对侧肌腱振动的猫的额外实验范例，类似于在人类中进行的实验范例。GS-MSRs条件同侧PBSt刺激单独和条件同侧PBSt刺激和对侧肌腱振动之间没有显着差异。目前的结果强烈建议从对侧组I纤维的MSR调制在放松的人类和麻醉猫的突触前机制的影响。
Mezzarane RA, Kohn AF, Couto-Roldan E, Martinez L, Flores A, Manjarrez E. Absence of effects of contralateral group I muscle afferents on presynaptic inhibition of Ia terminals in humans and cats. J Neurophysiol 108: 1176-1185, 2012. First published June 6, 2012; doi:10.1152/jn.00831.2011.-Crossed effects from group I afferents on reflex excitability and their mechanisms of action are not yet well understood. The current view is that the influence is weak and takes place indirectly via oligosynaptic pathways. We examined possible contralateral effects from group I afferents on presynaptic inhibition of Ia terminals in humans and cats. In resting and seated human subjects the soleus (SO) H-reflex was conditioned by an electrical stimulus to the ipsilateral common peroneal nerve (CPN) to assess the level of presynaptic inhibition (PSI_control). A brief conditioning vibratory stimulus was applied to the triceps surae tendon at the contralateral side (to activate preferentially Ia muscle afferents). The amplitude of the resulting H-reflex response (PSI_conditioned) was compared to the H-reflex under PSI_control, i.e., without the vibration. The interstimulus interval between the brief vibratory stimulus and the electrical shock to the CPN was -60 to 60 ms. The H-reflex conditioned by both stimuli did not differ from that conditioned exclusively by the ipsilateral CPN stimulation. In anesthetized cats, bilateral monosynaptic reflexes (MSRs) in the left and right L 7 ventral roots were recorded simultaneously. Conditioning stimulation applied to the contralateral group I posterior biceps and semitendinosus (PBSt) afferents at different time intervals (0-120 ms) did not have an effect on the ipsilateral gastrocnemius/soleus (GS) MSR. An additional experimental paradigm in the cat using contralateral tendon vibration, similar to that conducted in humans, was also performed. No significant differences between GS-MSRs conditioned by ipsilateral PBSt stimulus alone and those conditioned by both ipsilateral PBSt stimulus and contralateral tendon vibration were detected. The present results strongly suggest an absence of effects from contralateral group I fibers on the presynaptic mechanism of MSR modulation in relaxed humans and anesthetized cats.