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Three-week treadmill training changes the electrophysiological properties of spinal interneurons in the mice

  • Ke Chen
  • Renkai Ge
  • Yi Cheng
  • Yue DaiEmail author
Research Article
  • 69 Downloads

Abstract

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 (Vth) of − 37.3 ± 4.7 mV. Treadmill training reduced the rheobase by 4.8 ± 1.5 pA and Vth 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 Vth 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 Vth 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.

Keywords

Locomotion Treadmill training Spinal interneuron 5-HT modulation 

Notes

Acknowledgements

This study is supported by National Natural Science Foundation of China (Grant No: 31571222) and Contingent Construction Funds of East China Normal University (No: 11000-5154C1-15068) to YD. We thank Xing Ge and Nan Song for their technical support for mouse training.

Compliance with ethical standards

Conflict of interest

The authors declare no conflicts of interest.

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Shanghai Key Laboratory of Multidimensional Information Processing, School of Communication and Electronic EngineeringEast China Normal UniversityShanghaiChina
  2. 2.Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, School of Physical Education and Health CareEast China Normal UniversityShanghaiChina
  3. 3.School of Physical Education and Health CareEast China Jiaotong UniversityNanchangChina

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