Three-week treadmill training changes the electrophysiological properties of spinal interneurons in the mice
- 69 Downloads
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.
KeywordsLocomotion Treadmill training Spinal interneuron 5-HT modulation
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.
- Chen K, Cheng Y, Song N, Ge X, Dai Y (2017) Effects of three weeks of-treadmill training on the electrophysiological properties of spinal interneuron in the mice. CNS Abstract P-213, The 12th Biennial Conference of Chinese Neuroscience SocietyGoogle Scholar
- Chopek JW, MacDonell CW, Shepard PC, Gardiner KR, Gardiner PF (2018) Altered transcription of glutamatergic and glycinergic receptors in spinal cord dorsal horn following spinal cord transection is minimally affected by passive exercise of the hindlimbs. Eur J Neurosci 47:277–283CrossRefGoogle Scholar