Kelly E, Jenner P, Marsden C D
Biochem Pharmacol. 1985 Aug 1;34(15):2655-62. doi: 10.1016/0006-2952(85)90563-5.
Only high micromolar concentrations of dopamine and dopamine agonists altered spontaneous and KCl-evoked release of 3H-GABA and 3H-5HT from rat nigral slices in vitro. Apomorphine (100 microM) and dopamine (100 microM) enhanced the spontaneous release of 3H-5HT but the effect of dopamine was not reversed by haloperidol (1 microM). Both apomorphine (100 microM) and dopamine (100 microM) enhanced the KCl-evoked release of 3H-5HT but these effects were not reversed by haloperidol (1 microM). Apomorphine (10-250 microM) and dopamine (10-250 microM) inhibited 3H-5HT uptake into nigral synaptosomal preparations in a concentration-dependent manner. Accordingly, a major portion of the apparent effect of these drugs on 3H-5HT release may be due to inhibition of 3H-5HT uptake. Dopamine (100 and 1000 microM), amphetamine (100 microM), apomorphine (100 microM) and 2-amino-6,7-dihydroxytetralin (ADTN; 100 microM) were without effect on the spontaneous release of 3H-GABA from nigral slices. Apomorphine (100 microM) and ADTN (100 microM) reduced the KCl-evoked release of 3H-GABA from substantia nigra, an effect antagonized by haloperidol (1 microM). However, amphetamine (100 microM) and dopamine (100-1000 microM) were without effect on KCl-evoked 3H-GABA release. These results suggest that only high concentration of some dopamine agonists can modulate 3H-5HT and 3H-GABA release in substantia nigra. However, dopamine either had no effect, or its actions were not reversed by dopamine receptor blockade, so it appears unlikely that dendritic dopamine release will influence GABA and 5HT release in substantia nigra.
仅高微摩尔浓度的多巴胺和多巴胺激动剂能改变大鼠黑质脑片体外3H - GABA和3H - 5HT的自发释放以及KCl诱发的释放。阿扑吗啡（100微摩尔）和多巴胺（100微摩尔）增强了3H - 5HT的自发释放，但多巴胺的这种作用不能被氟哌啶醇（1微摩尔）逆转。阿扑吗啡（100微摩尔）和多巴胺（100微摩尔）均增强了KCl诱发的3H - 5HT释放，但这些作用也不能被氟哌啶醇（1微摩尔）逆转。阿扑吗啡（10 - 250微摩尔）和多巴胺（10 - 250微摩尔）以浓度依赖的方式抑制3H - 5HT摄取到黑质突触体标本中。因此，这些药物对3H - 5HT释放的明显作用的主要部分可能是由于对3H - 5HT摄取的抑制。多巴胺（100和1000微摩尔）、苯丙胺（100微摩尔）、阿扑吗啡（100微摩尔）和2 - 氨基 - 6,7 - 二羟基四氢萘（ADTN；100微摩尔）对黑质脑片3H - GABA的自发释放无影响。阿扑吗啡（100微摩尔）和ADTN（100微摩尔）减少了黑质KCl诱发的3H - GABA释放，这一作用被氟哌啶醇（1微摩尔）拮抗。然而，苯丙胺（100微摩尔）和多巴胺（100 - 1000微摩尔）对KCl诱发的3H - GABA释放无影响。这些结果表明，只有高浓度的某些多巴胺激动剂能调节黑质中3H - 5HT和3H - GABA的释放。然而，多巴胺要么无作用，要么其作用不能被多巴胺受体阻断所逆转，所以树突状多巴胺释放似乎不太可能影响黑质中GABA和5HT的释放。
