Liu X, Strecker R E, Brener J
Department of Psychology, State University of New York at Stony Brook, 11794-2500, USA.
Pharmacol Biochem Behav. 1998 Mar;59(3):737-45. doi: 10.1016/s0091-3057(97)00547-9.
This experiment examined the role of dopamine (DA) in the nucleus accumbens in regulating beam pressing and locomotor responses. Six rats were rewarded with sucrose on a partial reinforcement schedule for pressing force-sensitive beams. Open-field locomotor activity, and the force and timing characteristics of operant motor responses were recorded. It is known that low doses of apomorphine decrease DA tone through activating DA autoreceptors, resulting in suppression of both operant responses and locomotion. Our results showed that DA depletion in the nucleus accumbens, induced by bilateral injection of 6-hydroxydopamine, did not affect the force and timing of operant responses: neither did it reverse the suppressive effects of low doses of apomorphine on the force and timing of operant responses. However, accumbens DA depletion did block the suppressive effect of apomorphine on open-field locomotion. These results were interpreted as support for the hypothesis that the suppressive effects of low doses of apomorphine on locomotion, but not on operant beam pressing, are mediated mainly by DA autoreceptors in the mesolimbic pathway.
本实验研究了伏隔核中多巴胺（DA）在调节压杆和运动反应中的作用。六只大鼠在部分强化程序下，通过按压力敏杆获得蔗糖奖励。记录旷场运动活动以及操作性运动反应的力量和时间特征。已知低剂量的阿扑吗啡通过激活DA自身受体降低DA张力，导致操作性反应和运动均受到抑制。我们的结果表明，双侧注射6-羟基多巴胺诱导的伏隔核DA耗竭，并不影响操作性反应的力量和时间：它也没有逆转低剂量阿扑吗啡对操作性反应力量和时间的抑制作用。然而，伏隔核DA耗竭确实阻断了阿扑吗啡对旷场运动的抑制作用。这些结果被解释为支持以下假设：低剂量阿扑吗啡对运动的抑制作用，而非对操作性压杆的抑制作用，主要由中脑边缘通路中的DA自身受体介导。
