Swerdlow N R, Amalric M, Koob G F
Pharmacol Biochem Behav. 1987 Apr;26(4):765-9. doi: 10.1016/0091-3057(87)90609-5.
Locomotor activation produced by the indirect dopamine (DA) agonist amphetamine is reversed by the opiate-receptor antagonist naloxone. Since amphetamine-stimulated locomotion results from the release of DA within the nucleus accumbens (N.Acc.), it is possible that these effects of naloxone result either from a decrease in the pre-synaptic release of DA within the N.Acc. or from a disruption of the effects of DA at, or distal to, the post-synaptic DA receptor. In the present study, we investigated the effects of naloxone on the locomotor-activating properties of dopamine injected directly into the nucleus accumbens. Naloxone (0-2 mg/kg) had no significant effect of DA-stimulated locomotion; the lowest dose of naloxone tested (0.5 mg/kg) was shown to significantly disrupt the locomotor activation produced by amphetamine (0.5 mg/kg). In separate animals, very high doses of naloxone (5.0 mg/kg) had no significant effect on locomotor activation produced by the DA receptor agonist apomorphine in rats following 6-hydroxydopamine (6OHDA) denervation of the N.Acc. These results indicate that naloxone must disrupt amphetamine-stimulated locomotion through its action presynaptic to N.Acc. DA receptors.
间接多巴胺（DA）激动剂苯丙胺所产生的运动激活作用可被阿片受体拮抗剂纳洛酮逆转。由于苯丙胺刺激的运动是伏隔核（N.Acc.）内DA释放所致，因此纳洛酮的这些作用可能是由于N.Acc.内DA突触前释放减少，或者是由于DA在突触后DA受体处或其远端的作用受到破坏。在本研究中，我们研究了纳洛酮对直接注射到伏隔核内的多巴胺的运动激活特性的影响。纳洛酮（0 - 2毫克/千克）对DA刺激的运动没有显著影响；所测试的最低剂量纳洛酮（0.5毫克/千克）被证明能显著破坏苯丙胺（0.5毫克/千克）所产生的运动激活。在另外的动物实验中，在对N.Acc.进行6 - 羟基多巴胺（6OHDA）去神经支配后，非常高剂量的纳洛酮（5.0毫克/千克）对大鼠DA受体激动剂阿扑吗啡所产生的运动激活没有显著影响。这些结果表明，纳洛酮必定是通过其在N.Acc. DA受体突触前的作用来破坏苯丙胺刺激的运动。
