Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Department of Biomedical Science, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Front Neural Circuits. 2018 Jan 9;11:111. doi: 10.3389/fncir.2017.00111. eCollection 2017.
Motor fatigue occurring during prolonged physical activity has both peripheral and central origins. It was previously demonstrated that the excitability of motoneurons was decreased when a spillover of serotonin could activate extrasynaptic 5-HT receptors at the axon initial segment (AIS) of motoneurons. Here we investigated the impact of massive synaptic release of serotonin on motor behavior in an integrated preparation of the adult turtle performing fictive scratching behaviors. We found that a prolonged electrical stimulation of the raphe spinal pathway induced a reversible inhibition of the motor behavior that lasted several tens of seconds. The effect disappeared when the spinal cord was perfused with an antagonist for 5-HT receptors. By demonstrating a direct impact of serotonin on motor behavior, we suggest a central role of this monoamine behind central fatigue.
在长时间的体力活动中出现的运动疲劳既有外周起源也有中枢起源。此前已经证明，当血清素的溢出可以激活运动神经元轴突起始段（AIS）上的突触外 5-HT 受体时，运动神经元的兴奋性会降低。在这里，我们研究了大量血清素突触释放对成年海龟进行虚构抓挠行为的综合准备中运动行为的影响。我们发现，对中缝脊髓途径进行长时间的电刺激会引起运动行为的可逆抑制，持续数十秒。当脊髓被 5-HT 受体拮抗剂灌注时，该效应消失。通过证明血清素对运动行为的直接影响，我们认为这种单胺在后中枢疲劳中起中枢作用。
