Franklin S R, Tang A H
Upjohn Company, Kalamazoo, MI 49001, USA.
Psychopharmacology (Berl). 1995 Oct;121(4):480-4. doi: 10.1007/BF02246497.
Several dopamine agonists (apomorphine, quinpirole, 7-OH-DPAT, and U-91356A) suppressed locomotor activities of rats exploring a Y-maze, presumably through activation of dopamine autoreceptors. If brief electric shocks were applied to the grid floor during exploration, locomotion was unchanged in control rats, but the locomotor suppression from the dopamine agonists was converted to a profound stimulation. This locomotor stimulation was completely antagonized by pretreatment with sulpiride. SKF 38393 and clonidine produced no locomotor stimulation in the shock environment. To test whether the locomotor stimulant effect from dopamine agonists generalized to a food-reinforced behavior, rats were trained to lever-press for food according to a multiple (VI-10", VI-40") schedule. The above compounds only suppressed responding with no stimulation, and the suppressant effect on food-reinforced behavior was also blocked by sulpiride. It is concluded that the behavioral inhibitory effect from dopamine autoreceptor activation can be readily overcome by exteroceptive stimulation, which uncovers a powerful motor stimulant effect. This stimulant effect, however, did not generalize to lever-press responding for food.
几种多巴胺激动剂（阿扑吗啡、喹吡罗、7-羟基-DPAT和U-91356A）抑制了在Y迷宫中探索的大鼠的运动活动，推测是通过激活多巴胺自身受体实现的。如果在探索过程中对网格地板施加短暂电击，对照大鼠的运动不受影响，但多巴胺激动剂引起的运动抑制会转变为强烈的兴奋。这种运动兴奋完全被舒必利预处理所拮抗。SKF 38393和可乐定在电击环境中未产生运动兴奋。为了测试多巴胺激动剂的运动兴奋作用是否能推广到食物强化行为，根据多重（可变间隔10秒、可变间隔40秒）时间表训练大鼠按压杠杆获取食物。上述化合物仅产生抑制反应而无兴奋作用，且对食物强化行为的抑制作用也被舒必利阻断。结论是，多巴胺自身受体激活引起的行为抑制作用很容易被外感受性刺激克服，外感受性刺激揭示了一种强大的运动兴奋作用。然而，这种兴奋作用并没有推广到为获取食物而按压杠杆的反应中。
