School of Applied Physiology, The Georgia Institute of Technology, Atlanta, Georgia 30332-0356, USA.
J Appl Physiol (1985). 2013 Feb 15;114(4):429-35. doi: 10.1152/japplphysiol.01586.2011. Epub 2012 Dec 13.
Corticospinal excitability is modulated differently with norepinephrine and dopamine agonists, although both monoamines are released with heightened sympathetic nerve activity. The purpose of this study was to investigate the influence of physiological heightening of sympathetic nerve activity on corticospinal excitability in healthy humans. Subjects were divided into control and experimental groups. In each participant, motor-evoked potentials (MEPs) were measured from the resting first dorsal interosseous muscle of the right hand with transcranial magnetic stimulation (TMS) in two trials separated by 1 h. In the experimental group, sympathetic nerve activity was physiologically heightened during the second trial by applying lower body negative pressure (LBNP). In the control group, sympathetic nerve activity was not altered between the two trials. MEP peak-to-peak amplitude increased from trial 1 to trial 2 in the experimental group only. This increase was evident at a TMS intensity of 130% resting motor threshold and higher. It was concluded that physiological heightening of sympathetic nerve activity with LBNP enhances corticospinal excitability.
去甲肾上腺素和多巴胺激动剂对皮质脊髓兴奋性的调节方式不同，尽管这两种单胺类物质在交感神经活动增强时都会被释放。本研究旨在探讨生理性增强交感神经活动对健康人皮质脊髓兴奋性的影响。受试者分为对照组和实验组。在每个参与者中，用经颅磁刺激（TMS）在两次试验中测量右手第一背骨间肌的运动诱发电位（MEPs），两次试验间隔 1 小时。在实验组中，通过施加下体负压（LBNP）在第二次试验中生理性地增强交感神经活动。在对照组中，两次试验之间的交感神经活动没有改变。仅在实验组中，从第一次试验到第二次试验，MEP 峰峰值幅度增加。这种增加在 TMS 强度为 130%静息运动阈值及更高时明显。结论：LBNP 生理性增强交感神经活动可增强皮质脊髓兴奋性。
