Mclaughlin P J, Delevan C E, Carnicom S, Robinson J K, Brener J
Department of Psychology, State University of New York at Stony Brook, 11794-2500, USA.
Pharmacol Biochem Behav. 2000 Aug;66(4):803-9. doi: 10.1016/s0091-3057(00)00281-1.
Evidence has suggested that cannabinoids such as THC, the active ingredient in marijuana, cause deficits in motor control and the production of movement. However, the specific components of motor control that are affected by cannabinoids have yet to be identified. The present study used an operant beam-press paradigm with a force criterion to determine the effects of THC on different parts of the force-time trajectory. Seven rats were trained to press a beam with at least 50 g of force to receive a sugar solution. THC was injected, as was apomorphine (APO), a selective dopamine D(2)/D(1) receptor agonist that acts as an antagonist at low doses. Low doses of APO, which have been found to cause deficits in motor execution, were used as a control for the effects of THC. Average peak force of a given press, as well as rate of rise of force, were significantly lowered by THC, as well as by apomorphine. Past research suggests that deficits in the rate of rise of force that can be attributed to depletions of dopamine in the nigrostriatal pathway, as in the case of low doses of APO, reflect failures of motor unit recruitment rather than of motor memory. Similarities in the motor effects of THC and APO suggest that THC plays a role in recruitment and synchronization of motor neurons appropriate for a given task.
有证据表明，大麻素（如四氢大麻酚，大麻中的活性成分）会导致运动控制和动作产生方面的缺陷。然而，大麻素所影响的运动控制的具体组成部分尚未确定。本研究采用了一种带有力量标准的操作性压杆范式，以确定四氢大麻酚对力量-时间轨迹不同部分的影响。七只大鼠经过训练，需以至少50克的力量按压横杆以获取糖水。注射了四氢大麻酚，同时也注射了阿扑吗啡（APO），一种选择性多巴胺D(2)/D(1)受体激动剂，在低剂量时起拮抗剂作用。已发现低剂量的阿扑吗啡会导致运动执行方面的缺陷，被用作四氢大麻酚作用的对照。四氢大麻酚和阿扑吗啡均显著降低了给定按压的平均峰值力量以及力量上升速率。过去的研究表明，力量上升速率的缺陷可归因于黑质纹状体通路中多巴胺的耗竭，如低剂量阿扑吗啡的情况，这反映了运动单位募集的失败而非运动记忆的失败。四氢大麻酚和阿扑吗啡在运动效应上的相似性表明，四氢大麻酚在适合特定任务的运动神经元的募集和同步中发挥作用。
