Schmied A, Amalric M, Dormont J F, Farin D
Laboratoire de Neurobiologie et de Neuropharmacologie du Développement, CNRS-UA 1121, Université de Paris-Sud, Orsay, France.
Exp Brain Res. 1990;81(3):523-32. doi: 10.1007/BF02423501.
Interneurons in the Red Nucleus (RN) are known to be under cortical control and to exert an inhibitory action, mediated by GABAergic mechanisms, on the main output towards the spinal cord. The effects of discrete injections of a GABA receptor agonist (muscimol) or an antagonist (bicuculline) in the Red Nucleus were tested on a motor task performed by seven cats. The subjects were trained to release a lever with a flexion movement of the forelimb controlled by a reaction time (RT) paradigm. Muscimol as well as bicuculline increased RTs in a dose-dependent manner at doses below 100 ng. However the parameters of the force exerted on the lever were differentially altered by the two drugs. Muscimol increased RTs by slowing down the force change preceding movement as well as slightly delaying its latency. While bicuculline increased drastically the force change latency. It could also speed up the force change velocity for low doses. At higher doses (up to 500 ng) both drugs produced an arrest of the performance either associated with anxiety signs (bicuculline) or dystonic movements of the head followed by body rotations (muscimol). The strong motor impairments as well as the disruption of the conditioned performances following muscimol or bicuculline microinjection in the RN suggest an important functional role for GABAergic interneurons. Under the control of cortical afferences they can modulate rubrospinal activity and participate in the triggering of a conditioned movement.
红核（RN）中的中间神经元已知受皮质控制，并通过GABA能机制对脊髓的主要输出发挥抑制作用。在七只猫执行的一项运动任务中，测试了在红核中离散注射GABA受体激动剂（蝇蕈醇）或拮抗剂（荷包牡丹碱）的效果。实验对象经过训练，通过反应时间（RT）范式，以前肢屈曲运动来松开杠杆。在剂量低于100纳克时，蝇蕈醇和荷包牡丹碱均以剂量依赖方式增加反应时间。然而，两种药物对施加在杠杆上的力的参数产生了不同的改变。蝇蕈醇通过减缓运动前的力变化以及轻微延迟其潜伏期来增加反应时间。而荷包牡丹碱则大幅增加了力变化潜伏期。对于低剂量，它还可以加快力变化速度。在较高剂量（高达500纳克）时，两种药物都会导致行为停止，要么伴有焦虑迹象（荷包牡丹碱），要么伴有头部张力障碍性运动，随后是身体旋转（蝇蕈醇）。在红核中注射蝇蕈醇或荷包牡丹碱后出现的强烈运动障碍以及条件性行为的破坏表明，GABA能中间神经元具有重要的功能作用。在皮质传入的控制下，它们可以调节红核脊髓活动，并参与条件性运动的触发。
