versus [3H]spiperone. These data demonstrate that dihydroxidine has about ten-fold selectivity for D1/D2 receptors. More importantly, however, is the fact that dihydrexidine is a full agonist. Previously available agents, such as SKF38393 (1b), while being somewhat more selective for the D1 receptor, are only partial agonists. The isomeric cis-dihydroxybenzo[a]-phenanthridine neither stimulated cAMP synthesis
已发现反式-10,11-二羟基-5,6,6a,7,8,12b-六氢
苯并[a]菲啶(4a,dihydrexidine)是大鼠脑中
多巴胺D1受体的强效选择性激动剂。在激活
多巴胺敏感性大鼠纹状体
腺苷酸环化酶时,二氢己啶的
EC50约为70 nM,最大刺激等于或稍大于
多巴胺产生的刺激。在竞争大鼠纹状体匀浆中的[3H] SCH23390(1a)结合位点时,二氢己啶的IC50为12 nM,而与[3H]哌酮相比则为120 nM。这些数据证明
二氢吡啶对D1 / D2受体具有约十倍的选择性。然而,更重要的是二氢己定是完全激动剂的事实。先前可用的试剂,例如SKF38393(1b),虽然对D1受体的选择性更高,但仅是部分激动剂。异构体顺式-二羟基苯并[a]-
菲啶既不刺激c
AMP的合成,也不抑制
多巴胺诱导的c
AMP的合成。顺式异构体也缺乏对[3H] -1a结合位点的亲和力。标题化合物的N-甲基化使对D1位点的亲和力