Schmitt Kyle C, Zhen Juan, Kharkar Prashant, Mishra Manoj, Chen Nianhang, Dutta Aloke K, Reith Maarten E A
Department of Psychiatry, New York University School of Medicine, New York, New York, USA.
J Neurochem. 2008 Nov;107(4):928-40. doi: 10.1111/j.1471-4159.2008.05667.x. Epub 2008 Sep 11.
The widely abused psychostimulant cocaine is thought to elicit its reinforcing effects primarily via inhibition of the neuronal dopamine transporter (DAT). However, not all DAT inhibitors share cocaine's behavioral profile, despite similar or greater affinity for the DAT. This may be due to differential molecular interactions with the DAT. Our previous work using transporter mutants with altered conformational equilibrium (W84L and D313N) indicated that benztropine and GBR12909 interact with the DAT in a different manner than cocaine. Here, we expand upon these previous findings, studying a number of structurally different DAT inhibitors for their ability to inhibit [(3)H]CFT binding to wild-type, W84L and D313N transporters. We systematically tested structural intermediates between cocaine and benztropine, structural hybrids of benztropine and GBR12909 and a number of other structurally heterologous inhibitors. Derivatives of the stimulant desoxypipradrol (2-benzhydrylpiperidine) exhibited a cocaine-like binding profile with respect to mutation, whereas compounds possessing the diphenylmethoxy moiety of benztropine and GBR12909 were dissimilar to cocaine-like compounds. In tests with specific isomers of cocaine and tropane analogues, compounds with 3alpha stereochemistry tended to exhibit benztropine-like binding, whereas those with 3beta stereochemistry were more cocaine-like. Our results point to the importance of specific molecular features--most notably the presence of a diphenylmethoxy moiety--in determining a compound's binding profile. This study furthers the concept of using DAT mutants to differentiate cocaine-like inhibitors from atypical inhibitors in vitro. Further studies of the molecular features that define inhibitor-transporter interaction could lead to the development of DAT inhibitors with differential clinical utility.
被广泛滥用的精神兴奋剂可卡因被认为主要通过抑制神经元多巴胺转运体（DAT）来产生其强化作用。然而，并非所有DAT抑制剂都具有可卡因的行为特征，尽管它们对DAT的亲和力相似或更高。这可能是由于与DAT的分子相互作用存在差异。我们之前使用构象平衡改变的转运体突变体（W84L和D313N）进行的研究表明，苯海索和GBR12909与DAT的相互作用方式与可卡因不同。在这里，我们扩展了这些先前的发现，研究了许多结构不同的DAT抑制剂抑制[³H]CFT与野生型、W84L和D313N转运体结合的能力。我们系统地测试了可卡因和苯海索之间的结构中间体、苯海索和GBR12909的结构杂化物以及许多其他结构异源的抑制剂。兴奋剂去氧哌苯甲醇（2-二苯甲基哌啶）的衍生物在突变方面表现出类似可卡因的结合特征，而具有苯海索和GBR12909二苯甲氧基部分的化合物与类似可卡因的化合物不同。在对可卡因和托烷类似物的特定异构体进行的测试中，具有3α立体化学的化合物倾向于表现出类似苯海索的结合，而具有3β立体化学的化合物则更类似可卡因。我们的结果表明特定分子特征——最显著的是二苯甲氧基部分的存在——在确定化合物的结合特征方面的重要性。这项研究进一步拓展了利用DAT突变体在体外区分类似可卡因的抑制剂和非典型抑制剂的概念。对定义抑制剂-转运体相互作用的分子特征的进一步研究可能会导致开发出具有不同临床效用的DAT抑制剂。
