Marchi M, Augliera A, Codignola A, Lunardi G, Fedele E, Fontana G, Raiteri M
Istituto di Farmacologia e Farmacognosia, Università degli Studi di Genova, Italy.
Naunyn Schmiedebergs Arch Pharmacol. 1991 Sep;344(3):275-80. doi: 10.1007/BF00183000.
Dendrosomes prepared from substantia nigra are able to take up and release [3H]dopamine in a CA(2+)-dependent manner. The Vmax values of [3H]dopamine uptake in substantia nigra dendrosomes was about 5 times lower than that in caudate putamen synaptosomes. The pattern of the K(+)-dependency of the [3H]dopamine release in substantia nigra dendrosomes was significantly different from that found in caudate putamen synaptosomes. The release of [3H]dopamine evoked by 15 mmol/l KCl from superfused dendrosomes was increased in a concentration-dependent manner by acetylcholine. The maximal potentiation produced by acetylcholine was about 40%. The potentiation of [3H]dopamine release by 10 mumol/l acetylcholine was insensitive to mecamylamine but antagonized by atropine and by pirenzepine. The effects of acetylcholine on the release of [3H]acetylcholine from substantia nigra nerve endings was also studied. Exogenous acetylcholine added to the superfusion medium decreased in a concentration-dependent manner the release of acetylcholine. This effect was not antagonized by mecamylamine or pirenzepine but fully antagonized by atropine. The data suggest the existence, in the substantia nigra of the rat, of two distinct muscarinic receptor subtypes regulating respectively dopamine release from dopamine dendrites and acetylcholine release from cholinergic nerve terminals.
从黑质制备的树突体能够以依赖钙离子的方式摄取和释放[3H]多巴胺。黑质树突体中[3H]多巴胺摄取的Vmax值比尾状核壳核突触体中的低约5倍。黑质树突体中[3H]多巴胺释放的钾离子依赖性模式与尾状核壳核突触体中的显著不同。15 mmol/L氯化钾诱发的超融合树突体中[3H]多巴胺的释放，会因乙酰胆碱而以浓度依赖的方式增加。乙酰胆碱产生的最大增强作用约为40%。10 μmol/L乙酰胆碱对[3H]多巴胺释放的增强作用对美加明不敏感，但可被阿托品和哌仑西平拮抗。还研究了乙酰胆碱对黑质神经末梢释放[3H]乙酰胆碱的影响。添加到超融合培养基中的外源性乙酰胆碱以浓度依赖的方式降低了乙酰胆碱的释放。这种作用不被美加明或哌仑西平拮抗，但被阿托品完全拮抗。数据表明，在大鼠黑质中存在两种不同的毒蕈碱受体亚型，分别调节多巴胺树突释放多巴胺和胆碱能神经末梢释放乙酰胆碱。
