Medication development of agonist-type treatment agents for stimulant addiction

摘要--该项目取得了重大进展，并发表了几篇论文。在一篇值得注意的文章中，我们描述了部分转运蛋白底物的发现，这些转运蛋白底物释放单胺递质的能力有限。这些化合物可用于治疗成瘾和ADHD，而不会造成典型的兴奋剂相关不良反应(即滥用倾向)。 生物胺转运蛋白的研究。14.鉴定生物胺转运体的低效“部分”底物。(2012)J.Pharmacol.实验在那里。341：251-261。已有几种化合物显示出低效的“部分底物”活性。在这里，我们测试了一种假设，即这种效应的机制是诱导神经递质外流的速度比完全底物产生的速度更慢。生物胺转运体释放分析在大鼠脑突触体中进行，并遵循公开发表的程序。(3)用H1-甲基-4-苯基吡啶(MPP(+))测定多巴胺(DA)和去甲肾上腺素(NOR)神经末梢的释放，用5-羟色胺(5-HT)测定5-羟色胺(5-HT)的释放。通过测量加入不同受试化合物后(3)HMPP(+)的外流，对DA转运体(DAT)介导的外流进行了详细的时程评估。体内微透析实验比较了全底物()-1-(2-萘基)丙烷-2-胺(PAL-287)和(S)-N-甲基-1-(2-萘基)丙烷-2-胺(PAL-1046)与部分DAT/5-羟色胺转运体底物(S)-N-乙基-1-(2-萘基)丙烷-2-胺(PAL-1045)对大鼠伏隔核细胞外多巴胺和5-羟色胺的影响。体外释放试验表明，三种转运蛋白都有部分底物活性。在DAT外排实验中，D-苯丙胺(满底物)促进快速外排(K1=0.24min(-1))和慢外排(K2=0.008分钟(-1))。对于部分DAT底物，K1=#8764；0.04min(-1)，K2接近零。体内微透析实验表明，部分底物(PAL-1045)对细胞外多巴胺和5-羟色胺的升高作用明显低于对照全底物。我们的结论是，低效的部分DAT底物促进外排的速度比完全底物慢，而且“偏好”反映了超慢的K2常数，这在功能上限制了这些化合物增加细胞外DA的能力。我们推测，部分生物胺转运体底物与转运体结合，但在诱导反向转运体活动所需的构象变化方面效果较差。

Summary- Significant progress was made on this project, and several papers were published. In one notable article, we describe the discovery of partial transporter substrates which have limited ability to release monoamine transmitters. Such compounds could have utility for treating addiction and ADHD, without causing typical stimulant-associated adverse effects (i.e., abuse liability). Studies of the biogenic amine transporters. 14. Identification of low-efficacy "partial" substrates for the biogenic amine transporters. (2012) J. Pharmacol. Exp. Ther. 341:251-261. Several compounds have been identified that display low-efficacy, "partial substrate" activity. Here, we tested the hypothesis that the mechanism of this effect is a slower rate of induced neurotransmitter efflux than that produced by full substrates. Biogenic amine transporter release assays were carried out in rat brain synaptosomes and followed published procedures. (3)H1-methyl-4-phenylpyridinium (MPP(+)) was used to assess release from dopamine (DA) and norepinephrine nerve terminals, whereas (3)H5-hydroxytryptamine (5-HT) was used to assess release from 5-HT nerve terminals. A detailed time-course evaluation of DA transporter (DAT)-mediated efflux was conducted by measuring the efflux of (3)HMPP(+) after the addition of various test compounds. In vivo microdialysis experiments compared the effects of the full substrates ()-1-(2-naphthyl)propan-2-amine (PAL-287) and (S)-N-methyl-1-(2-naphthyl)propan-2-amine (PAL-1046), to that of a partial DAT/5-HT transporter substrate (S)-N-ethyl-1-(2-naphthyl)propan-2-amine (PAL-1045) on extracellular DA and 5-HT in the nucleus accumbens of the rat. The in vitro release assays demonstrated that partial substrate activity occurs at all three transporters. In the DAT efflux experiments, D-amphetamine (full substrate) promoted a fast efflux (K1 = 0.24 min(-1)) and a slow efflux (K2 = 0.008 min(-1)). For the partial DAT substrates, K1 = ∼0.04 min(-1), and K2 approximated zero. The in vivo microdialysis experiments showed that the partial substrate (PAL-1045) was much less effective in elevating extracellular DA and 5-HT than the comparator full substrates. We conclude that low-efficacy partial DAT substrates promote efflux at a slower rate than full substrates, and "partiality" reflects the ultra-slow K2 constant, which functionally limits the ability of these compounds to increase extracellular DA. We speculate that partial biogenic amine transporter substrates bind to the transporter but are less effective in inducing conformational changes required for reverse transport activity.