Bioactivity Of Opioidmimetic Substances

工作总结：最近开发的阿片类物质在小鼠体内的镇痛活性与吗啡进行了比较，并使用特定的阿片受体拮抗剂来评估它们的作用模式。抗伤害作用曲线与体外功能药理数据(GPI、豚鼠回肠和微血管密度、小鼠输精管)相似，反映了阿片受体的结合亲和力(有关化合物与增量和Mu阿片受体相互作用的详细信息，请参阅项目1)。一系列新型的含DMT的烷基和烷基吡津酮类阿片类化合物在体内具有优异的活性。特别是，其中一种在静脉注射后的甩尾试验中产生的镇痛效果是吗啡的60-71倍。给药：脊髓效应(甩尾试验)比脊柱上效应(热板试验)强2-3倍。特别是，化合物3-[4‘-Dmt-aminobutyl)-6-(3’-Dmt-aminopropyl)-5-methyl-2(1H)pyrazinone具有很高的亲和力(Ki-Mu=0.02 nM)、选择性(Delta/Mu=1,520)和激动剂活性(GpI，IC_(50)=1.7 nM)，在所有的测定体系中对Delta受体的活性都很弱。这种化合物主要通过使用Mu-2受体亚型产生脊髓抗伤害性感觉；然而，Mu-1亚型在冈上占主导地位。南卡罗来纳州注射产生了中枢神经系统介导的抗伤害作用，提供了证据，证明该化合物通过了胃肠道上皮和调节血脑屏障(BBB)的微血管紧密连接的膜屏障。然而，在每天注射相当于吗啡的一周后，获得了耐受性，这表明这两种物质在u-阿片受体上通过类似的机制发挥作用。 另一类含DMT的吡津酮类化合物3，6-双-[DMT-NH-(CH2)n]-2(1H)-吡津酮类化合物不仅具有中枢(CNS)介导的镇痛作用，而且是一种口服生物利用型阿片类药物。这些对称性物质对mU-阿片受体具有较高的亲和力(Ki=0.04-0.12 nM)，对GPI有较强的血管紧张性(IC50=1.3-1.9 nM)。它们在体内通过静脉注射产生镇痛作用。这种药物的效力是吗啡的50到63倍，但只有S.C.注射时的一半左右。或者口服，它仍然比其他内源性阿片肽大几个数量级，而且重要的是，它没有被糖基化、金刚烷、甘油三酯、卤素、抗体、生物素、大分子有机分子、C端羧基(这些化合物中不存在)的酯化或Tyr或DMT的酚羟基的O-酰化修饰，也不需要将它们吸收到聚山梨酸酯包被的纳米颗粒上以通过BBB诱导摄取。 研究了一组内吗啡-1和-2中含有DMT而不是Tyr的MU阿片类物质，揭示了它们作用模式的差异，这也有助于区分这些结构相关的化合物。虽然两种化合物都有很强的镇痛作用，但它们的作用方式和镇痛程度明显不同。在体外和体内，DMT使所有测量的活度参数增加了几个数量级。

Summary of Work: The analgesic activity of recently developed opioidmimetic substances was determined in vivo in mice in comparison to morphine and using specific opiate-receptor antagonists to assess their mode of action. The antinociception profile paralleled that of the in vitro functional pharmacological data (GPI,guinea-pig ileum and MVD, mouse vas deferens), and reflected the opioid-receptor binding affinity (see, Project 1 for details on the interaction of compounds with delta- and mu-opioid receptors). A series of novel Dmt-containing alkyl and alkyl pyrazinone group as opioidmimetic compounds had exceptional activity in vivo. In particular, one of which was 60- to 71-fold more potent than morphine in generating analgesia by the tail-flick test after i.c.v. administration; the spinal (tail-flick test) is more potent than the supraspinal effects (hot-plate test) by a factor of 2-3. In particular, the compound 3-[4'-Dmt-aminobutyl)-6-(3'-Dmt-aminopropyl)-5-methyl-2(1H)pyrazinone had very high affinity (Ki mu = 0.02 nM), selectivity (delta/mu = 1,520) and agonist activity (GPI, IC50 = 1.7 nM) with weak activity toward the delta receptor in all assay systems. This compound acted to produce spinal antinociception primarily through spinal antinociception using the mu-2 receptor subtype; however, the mu-1 subtype dominates supraspinally. The s.c. injection produced CNS-mediated antinociception, providing evidence the compound passed through membrane barriers in both the gastrointestinal epithelium and in the microcapillary tight junctions that regulate the blood-brain barrier (BBB). However, a tolerance was obtained after a week of daily injections that was equivalent to morphine and suggests that both substances act through similar mechanisms at mu-opioid receptors. Another class of Dmt-containing pyrazinone compounds, the 3,6-bis-[Dmt-NH-(CH2)n]-2(1H)-pyrazinone compounds not only exhibited central (CNS) mediated analgesia, but also were orally bioavailable opioid mimetics. These symmetric substances displayed high affinity for mu-opioid receptors (Ki = 0.04-0.12 nM) and potent angonism on GPI (IC50 = 1.3-1.9 nM). They produced analgesia in vivo by i.c.v. administration that was 50- to 63-fold more potent than morphine, but only about half as potent when injected s.c. or administered orally, which is still orders of magnitude greater than other endogenous opioid peptides and, importantly, were unmodified by glycosylation, adamantane, triglycerides, halogens, antibody, biotin, bulky organic molecules, esterification of a C-terminal carboxyl group (of which none exist in these compounds) or O-acylation of the phenolic hydroxyal group of Tyr or Dmt, nor was it necessary to absorb them onto polysorbate coated nanoparticles to induced uptake through the BBB. Studies a group of mu opioid substances containing Dmt in lieu of Tyr in endomorphins-1 and -2 revealed differences in their mode of action that also serve to differential these stucturally related compounds. Whereas both compounds exhibited potent analgesia, their mode of action and degree of analgesia was significantly different. Dmt enhanced all measured parameters of activity by orders of magnitude both in vitro and in vivo.