Meller E, Enz A, Goldstein M
Millhauser Laboratories and Department of Psychiatry, New York University School of Medicine, NY 10016.
Eur J Pharmacol. 1988 Oct 11;155(1-2):151-4. doi: 10.1016/0014-2999(88)90413-x.
N-propylnorapomorphine (NPA) dose dependently increased rat striatal ACh levels (ED50 = 18 micrograms/kg). After irreversible dopamine (DA) receptor inactivation with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), neither the ED50 nor the slope of the dose-response curve for NPA was altered, whereas the maximal response was reduced to 56% of control. Analysis of the results yielded a linear relationship between receptor occupancy and response (i.e. no receptor reserve). In contrast, DA autoreceptors display a large receptor reserve for NPA. The results support the hypothesis that a differential receptor reserve at pre- vs. postsynaptic DA receptors in rat striatum accounts for the autoreceptor selectivity of DA agonists.
N-丙基去甲阿扑吗啡（NPA）可剂量依赖性地增加大鼠纹状体乙酰胆碱（ACh）水平（半数有效剂量[ED50]=18微克/千克）。在用N-乙氧羰基-2-乙氧基-1,2-二氢喹啉（EEDQ）使多巴胺（DA）受体不可逆失活后，NPA的ED50和剂量反应曲线的斜率均未改变，而最大反应降低至对照的56%。对结果的分析得出受体占有率与反应之间呈线性关系（即无受体储备）。相比之下，DA自身受体对NPA表现出较大的受体储备。这些结果支持以下假说：大鼠纹状体中突触前与突触后DA受体的受体储备差异可解释DA激动剂的自身受体选择性。
