Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic Engineering, East China Normal University, Shanghai, 200241, China.
School of Physical Education and Health Care, East China Jiaotong University, Nanchang, 330013, China.
Exp Brain Res. 2019 Nov;237(11):2925-2938. doi: 10.1007/s00221-019-05647-3. Epub 2019 Sep 7.
It was shown in previous studies that endurance training enhanced excitability of rat spinal motoneurons. However, the influence of the training on the spinal interneurons remains unclear. In this study, we investigated the training effects on spinal interneurons in dorsal and ventromedial area in mice (P42-P50). The electrophysiological properties of the interneurons were recorded from spinal cord slices (T13-L6) by whole-cell patch-clamp recording. The interneurons could be classified into three types based on their response to step currents: single spike (type 1), phasic firing (type 2), and tonic firing (type 3) in both control and trained mice. Interneurons collected from control mice possessed rheobase of 11.3 ± 6.0 pA and voltage threshold (V) of - 37.3 ± 4.7 mV. Treadmill training reduced the rheobase by 4.8 ± 1.5 pA and V by 3.1 ± 1.2 mV (P < 0.05). Furthermore, the training effects were dependent on the distribution and types of the interneurons. Treadmill training hyperpolarized V and decreased rheobase in ventromedial interneurons, while the significant change was observed only in the action potation height of the interneurons in dorsal horn. Treadmill training also hyperpolarized V and increased input resistance in type 3 interneurons, but none of these changes was shown in type 1 and 2 interneurons. Bath application of 5-HT (10-20 μM) increased the neuronal excitability in both control and trained mice. Serotonin had similar effect on membrane properties of the interneurons collected from both groups. This study suggested that treadmill training increased excitability of spinal interneurons of the mice and thus would make the spinal motor system easier to generate locomotion.
先前的研究表明，耐力训练增强了大鼠脊髓运动神经元的兴奋性。然而，训练对脊髓中间神经元的影响尚不清楚。在这项研究中，我们研究了训练对小鼠（P42-P50）背侧和腹内侧区域脊髓中间神经元的影响。通过全细胞膜片钳记录，从脊髓切片（T13-L6）记录中间神经元的电生理特性。根据对阶跃电流的反应，中间神经元可分为三种类型：在对照和训练小鼠中均为单峰（1 型）、相发射（2 型）和紧张发射（3 型）。从对照小鼠中收集的中间神经元的基强度为 11.3±6.0 pA，电压阈值（V）为-37.3±4.7 mV。跑步机训练使基强度降低了 4.8±1.5 pA，V 降低了 3.1±1.2 mV（P<0.05）。此外，训练效果取决于中间神经元的分布和类型。跑步机训练使腹内侧中间神经元的 V 超极化，并降低基强度，而在背角中间神经元中仅观察到动作电位高度的显著变化。跑步机训练还使 V 超极化，并增加 3 型中间神经元的输入电阻，但在 1 型和 2 型中间神经元中未观察到这些变化。5-HT（10-20 μM）的浴液应用增加了对照和训练小鼠中间神经元的兴奋性。5-HT 对两组中间神经元的膜特性具有相似的作用。本研究表明，跑步机训练增加了小鼠脊髓中间神经元的兴奋性，从而使脊髓运动系统更容易产生运动。
