Laboratory of Neuromuscular Plasticity, Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland.
J Physiol. 2012 Apr 1;590(7):1721-36. doi: 10.1113/jphysiol.2011.224931. Epub 2012 Feb 20.
Recent studies on the restoration of locomotion after spinal cord injury have employed robotic means of positioning rats above a treadmill such that the animals are held in an upright posture and engage in bipedal locomotor activity. However, the impact of the upright posture alone, which alters hindlimb loading, an important variable in locomotor control, has not been examined. Here we compared the locomotor capabilities of chronic spinal rats when placed in the horizontal and upright postures. Hindlimb locomotor movements induced by exteroceptive stimulation (tail pinching) were monitored with video and EMG recordings. We found that the upright posture alone significantly improved plantar stepping. Locomotor trials using anaesthesia of the paws and air stepping demonstrated that the cutaneous receptors of the paws are responsible for the improved plantar stepping observed when the animals are placed in the upright posture.We also tested the effectiveness of serotonergic drugs that facilitate locomotor activity in spinal rats in both the horizontal and upright postures. Quipazine and (±)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT) improved locomotion in the horizontal posture but in the upright posture either interfered with or had no effect on plantar walking. Combined treatment with quipazine and 8-OH-DPAT at lower doses dramatically improved locomotor activity in both postures and mitigated the need to activate the locomotor CPG with exteroceptive stimulation. Our results suggest that afferent input from the paw facilitates the spinal CPG for locomotion. These potent effects of afferent input from the paw should be taken into account when interpreting the results obtained with rats in an upright posture and when designing interventions for restoration of locomotion after spinal cord injury.
最近对脊髓损伤后运动功能恢复的研究采用了机器人手段，将大鼠置于跑步机上方，使动物保持直立姿势并进行双足运动活动。然而，单独直立姿势的影响，改变了后肢负重，这是运动控制中的一个重要变量，尚未被研究。在这里，我们比较了慢性脊髓损伤大鼠在水平和直立姿势下的运动能力。通过视频和肌电图记录监测外感受刺激（尾巴刺痛）引起的后肢运动。我们发现，单独直立姿势就能显著改善足底踏步行走。使用爪子麻醉和空气踏步行走的运动试验表明，爪子的皮肤感受器负责当动物处于直立姿势时观察到的足底踏步行走的改善。我们还测试了促进脊髓损伤大鼠运动活动的 5-羟色胺能药物在水平和直立姿势下的有效性。Quipazine 和（±）-8-羟基-2-（二丙基氨基）四氢萘氢溴酸盐（8-OH-DPAT）改善了水平姿势下的运动，但在直立姿势下，要么干扰，要么对足底行走没有影响。Quipazine 和 8-OH-DPAT 的联合治疗在较低剂量下可显著改善两种姿势下的运动活动，并减轻对外感受刺激激活运动中枢模式发生器的需求。我们的结果表明，来自爪子的传入输入有助于脊髓运动中枢模式发生器进行运动。在解释直立姿势下大鼠的结果和设计脊髓损伤后恢复运动的干预措施时，应考虑来自爪子的传入输入的这些强烈影响。
