Université de Technologie, Compiègne CNRS UMR 7338, Biomécanique et Bioingénierie, F-60205 Compiègne Cedex, France.
Neurosci Lett. 2012 Aug 15;523(2):154-7. doi: 10.1016/j.neulet.2012.06.067. Epub 2012 Jul 4.
Alteration of Soleus (SOL) H-reflex has been reported after prolonged vibratory exposure and it was hypothesized that presynaptic inhibition, known to depress the H-reflex during vibration, largely contributed to the H-reflex changes. To confirm this hypothesis, the purpose of the present study was to quantify the SOL H-reflex changes between sitting and standing positions (postural modulation) with or without the after-effects of 1h of Achilles tendon vibration. Indeed, postural modulation of the SOL H-reflex has been reported to inform on the level of presynaptic inhibition exerted on Ia afferents. SOL H-reflex and M waves were measured in healthy voluntary subjects in both sitting and standing positions before and after 1h of Achilles vibration (frequency: 50 Hz) applied in sitting position (vibration group, n=11) or before and after 1h of sitting position only (control group, n=6). SOL H(max)/M(max) ratios were calculated. Furthermore, in order to quantify presynaptic inhibition induced by prolonged vibration, an index of SOL H-reflex postural modulation was calculated as the standing H(max)/M(max) ratio relative to the sitting one. After 1h of Achilles tendon vibration, a significant decrease in the SOL H(max)/M(max) ratio was observed both in sitting and standing positions (p<0.05). However, the decrease was more pronounced in the standing position, leading to a significant decrease of the index of SOL H-reflex postural modulation. Those results suggest that presynaptic inhibition could have largely contributed to the H-reflex decrease observed after one bout of vibration.
长期振动暴露后，比目鱼肌（SOL）H 反射会发生变化，据推测，已知在振动过程中抑制 H 反射的突触前抑制在很大程度上导致了 H 反射的变化。为了证实这一假设，本研究的目的是量化在坐姿和站位（姿势调制）之间，是否存在跟腱振动 1 小时后的后效，SOL H 反射的变化。事实上，已经有报道称，SOL H 反射的姿势调制可以反映 Ia 传入纤维上施加的突触前抑制水平。在跟腱振动（频率：50Hz）1 小时前和后，在坐姿下（振动组，n=11）或仅在坐姿下 1 小时前和后，测量了健康志愿者在坐姿和站位下的 SOL H 反射和 M 波（对照组，n=6）。计算 SOL H(max)/M(max) 比值。此外，为了量化长期振动引起的突触前抑制，计算了 SOL H 反射姿势调制指数，作为站立时的 H(max)/M(max) 比值相对于坐姿时的比值。跟腱振动 1 小时后，在坐姿和站位下，SOL H(max)/M(max) 比值均显著降低（p<0.05）。然而，在站立位时下降更为明显，导致 SOL H 反射姿势调制指数显著降低。这些结果表明，突触前抑制可能在单次振动后观察到的 H 反射下降中起了很大作用。
