Complete Conversion of Brain D2 Dopamine Receptors from the High‐ to the Low‐Affinity State for Dopamine Agonists, Using Sodium Ions and Guanine Nucleotide
Complete Conversion of Brain D2 Dopamine Receptors from the High‐ to the Low‐Affinity State for Dopamine Agonists, Using Sodium Ions and Guanine Nucleotide
复制标题
使用钠离子和鸟嘌呤核苷酸将大脑 D2 多巴胺受体从多巴胺激动剂的高亲和力状态完全转变为低亲和力状态
作者：
Dimitris Grigoriadis;P. Seeman
由于以前的工作表明，大脑D2，3，4-二羟基苯乙胺(DA)受体只有部分从高亲和力状态转换到低亲和力状态，因此我们在这里测试是否有可能将这些受体完全转换为低亲和力状态。首先要解决的是大鼠纹状体匀浆中与多巴胺能部位和非多巴胺能部位结合的[~3H]螺环酮成分。因此，在50μ的MS-舒必利(阻断多巴胺能部位)存在的情况下，我们首先确定了5-羟色胺能激动剂比多巴胺或去甲肾上腺素更有效地抑制了[~3H]螺环酮的残留结合(约20%)，从而确定了[~3H]螺环酮结合的5-羟色胺能成分。因此，多巴胺(或ADTN)抑制高亲和力部位(解离常数为10 nM的多巴胺)、低亲和力部位(解离常数为2,000 nM的多巴胺)和5-羟色胺能部位(解离常数为50,000 nM的多巴胺)的[~3H]螺环酮的结合。在无钠离子时，高亲和力部位约50%被[~3H]螺环酮占据，鸟嘌呤核苷酸对这一比例没有影响。然而，在120 mM的氯化钠存在下，高亲和力位点被还原到15%，鸟嘌呤核苷酸完全消除了这个高亲和力位点，100%的位点已经完全转换到它们的低亲和力状态。用[~H]-N-丙基去甲吗啡标记多巴胺受体的高亲和力状态，在45 mM、69 mM和202 mM KCl时，50%转化为低亲和力状态。我们的结论是，如果适当考虑[~3H]螺环酮结合的5-羟色胺能成分，在氯化钠和鸟嘌呤核苷酸存在的情况下，将脑D2多巴胺受体完全转换为低亲和力状态是可能的。
Since previous work had shown that brain D2 3,4‐dihydroxyphenylethylamine (dopamine) receptors were only partly converted from their high‐affinity state to their low‐affinity state, we here tested whether it was possible to obtain a complete 100% conversion of these receptors into their low‐affinity state. It was first essential to resolve the components of [3H]spiperone binding to dopaminergic sites and nondopaminergic sites in rat striatal homogenates. In the presence of 50 μMS‐sulpiride (to occlude the dopaminergic sites), therefore, we first determined that the residual binding of [3H]spiperone (approximately 20%) was inhibited by serotonergic agonists much more effectively than dopamine or noradrenaline, thus identifying the serotonergic component of [3H]spiperone binding. Thus, dopamine (or ADTN) inhibited the binding of [3H]spiperone at a high‐affinity site (with dissociation constant of 10 nM dopamine), at a low‐affinity site (with dissociation constant of 2,000 nM dopamine), and at the serotonergic site (with dissociation constant of 50,000 nM dopamine). In the absence of sodium ions, the high‐affinity site was about 50% occupied by [3H]spiperone, and guanine nucleotide had no effect on this proportion. In the presence of 120 mM NaCl, however, the high‐affinity site was reduced to 15% and guanine nucleotide completely eliminated this high‐affinity site, 100% of the sites having been completely converted to their low‐affinity state. Using [3H]N‐propyl‐norapomorphine to label the high‐affinity state of the dopamine receptor, 50% conversion into the low‐affinity state occurred at 45 mM NaCl, 69 mM NaCl, and 202 mM KCl. We conclude that it is possible to convert brain D2 dopamine receptors completely into their low‐affinity state, in the presence of NaCl and a guanine nucleotide, providing that appropriate allowance is made for the serotonergic component of [3H]spiperone binding.
定量测定与大鼠纹状体腺苷酸环化酶的激活无关的多巴胺受体亚型。
DOI：
10.1073/pnas.79.23.7561
发表时间：
1982
影响因子：
11.1
作者：
Huff,RM;Molinoff,PB
通讯作者：
Molinoff,PB
钠离子调节膜和溶解制剂中与人血小板 α2-肾上腺素能受体的激动剂和拮抗剂相互作用。
影响因子：
3.6
作者：
Limbird,LE;Speck,JL;Smith,SK
通讯作者：
Smith,SK