HIGH-AFFINITY [H-3] PAROXETINE BINDING TO SEROTONIN UPTAKE SITES IN HUMAN-BRAIN TISSUE
HIGH-AFFINITY [H-3] PAROXETINE BINDING TO SEROTONIN UPTAKE SITES IN HUMAN-BRAIN TISSUE
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DOI：
10.1016/0006-8993(89)90511-8
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发表时间：
1989-05-08
期刊：
影响因子：
2.9
通讯作者：
MARCUSSON, J
中科院分区：
文献类型：
--
作者：
BACKSTROM, I;BERGSTROM, M;MARCUSSON, J
[~3H]帕罗西汀与人脑组织的结合特性。壳核和额叶皮质的竞争研究显示，5-羟色胺(5-羟色胺)(Ki 1-3微米)和西酞普兰(Ki 0.6 NM)敏感的结合模式取代了相同的结合量。然而，地昔帕明、去甲基美汀和氟西汀取代了额外的结合(10%-20%)，这些竞争者符合双部位结合模型，高亲和力组分在纳摩尔范围内，低亲和力组分在微摩尔范围内。高亲和力组分接近5-羟色胺和西酞普兰敏感的结合组分。大多数[~3H]帕罗西汀结合部位是蛋白酶敏感的，但低亲和力(µM)部位似乎是蛋白酶抗性的。根据这些发现，只有代表对30微米5-羟色胺敏感的部分的[~3H]帕罗西汀结合(或例如0.3微米去甲肾上腺素)被认为是特异性结合。这个结合组分是饱和的，整个大脑的表观结合亲和力(Kd)为0.03-0.05 nM。下丘脑和黑质的结合密度最高(Bmax为500fmol/mg蛋白)。基底节达到中等密度(Bmax为200fmol/mg蛋白)，而皮质区Bmax值较低(<；100fmol/mg蛋白)。Bmax值以小脑皮质最低(30Fmol/mg蛋白)。低浓度的5-羟色胺、丙咪嗪和去甲肾上腺素可竞争性抑制[~3H]帕罗西汀的结合，提示5-羟色胺摄取的底物识别部位被标记。作用于多巴胺能、去甲肾上腺素、组胺能、5-HT1、5-HT2和胆碱能毒碱的化合物在100微米的浓度下不影响结合。结论是，[~3H]帕罗西汀是人脑中5-羟色胺摄取部位的标志物，前提是对特定结合进行了充分的药理学定义。
[3H]Paroxetine binding to human brain tissue was characterized. Competition studies in the putamen and frontal cortex revealed single-site binding models for binding sensitive to 5-hydroxytryptamine (5-HT) (Ki 1-3 .mu.M) and citalopram (Ki 0.6 nM), which displaced the same amount of binding. However, desipramine, norzimeldine and fluoxetine displaced additional binding (10-20%) and these competitors fitted two-site binding models with high affinity components in the nanomolar range and low affinity components in the micromolar range. The high affinity components approximated the 5-HT- and citalopram-sensitive binding fraction. Most of the [3H]paroxetine binding sites were protease-sensitive, but the low-affinity (.mu.M) sites appeared to be protease-resistant. Based on these findings, only the [3H]paroxetine binding representing the fraction sensitive to 30 .mu.M 5-HT (or e.g. 0.3 .mu.M norzimeldine), was regarded as specific binding. This binding fraction was saturable with an apparent binding affinity (Kd) of 0.03-0.05 nM throughout the brain. The highest binding densities were obtained in the hypothalamus and substantia nigra (Bmax 500 fmol/mg protein). The basal ganglia reached intermediate densities (Bmax 200 fmol/mg protein), whereas cortical areas had low Bmax values (< 100 fmol/mg protein). The lowest Bmax value was noted in cerebellar cortex (30 Fmol/mg protein). The [3H]paroxetine binding was competitively inhibited by low concentrations of 5-HT, imipramine and norzimeldine, suggesting that the substrate recognition site for 5-HT uptake was labeled. Compounds active at dopaminergic, noradrenergic, histaminergic, 5-HT1, 5-HT2 and cholinergic muscarinic sites did not affect the binding at 100 .mu.M concentrations. It is concluded that [3H]paroxetine is a marker for the 5-HT uptake site in the human brain, provided that an adequate pharmacological definition of specific binding is performed.