Bioactivity Of Opioidmimetic Substances

工作总结：最近开发的阿片样物质的镇痛活性测定在小鼠体内与吗啡相比，并使用特定的阿片受体拮抗剂，以评估其作用模式。抗伤害感受特征与体外功能药理学数据（GPI、豚鼠回肠和MVD、小鼠输精管）一致，并反映了阿片受体结合亲和力（有关化合物与δ-和μ-阿片受体相互作用的详细信息，请参见项目1）。一系列新的含Dmt的烷基和烷基吡嗪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i. c. v.给药后通过甩尾试验产生镇痛作用方面比吗啡强60- 71倍;脊髓（甩尾试验）比脊髓上效应（热板试验）强2-3倍。特别地，化合物3-[4 ′-Dmt-氨基丁基）-6-（3 ′-Dmt-氨基丙基）-5-甲基-2（1H）吡嗪酮具有非常高的亲和力（Ki μ = 0.02 nM）、选择性（delta/mu = 1，520）和激动剂活性（GPI，IC 50 = 1.7 nM），在所有测定系统中对delta受体具有弱活性。该化合物主要通过使用mu-2受体亚型的脊髓抗伤害感受来产生脊髓抗伤害感受;然而，mu-1亚型在脊髓上占主导地位。南卡罗来纳注射产生CNS介导的抗伤害感受，提供了化合物通过胃肠上皮和调节血脑屏障（BBB）的微毛细血管紧密连接中的膜屏障的证据。然而，在每天注射一周后获得了与吗啡相当的耐受性，这表明两种物质通过类似的机制作用于μ阿片受体。 另一类含Dmt的吡嗪酮化合物，3，6-双-[Dmt-NH-（CH 2）n]-2（1H）-吡嗪酮化合物不仅表现出中枢（CNS）介导的镇痛作用，而且是口服生物可利用的阿片样物质模拟物。这些对称物质对μ-阿片受体表现出高亲和力（Ki = 0.04-0.12 nM），对GPI表现出强的血管紧张作用（IC 50 = 1.3-1.9 nM）。它们在体内通过i. c. v.注射产生的镇痛作用比吗啡强50- 63倍，但在皮下注射时只有大约一半的效力。或口服给药，其仍然比其他内源性阿片肽大几个数量级，并且重要的是，其未被糖基化、金刚烷、甘油三酯、卤素、抗体、生物素、大体积有机分子、C-末端羧基的酯化（在这些化合物中不存在）或Tyr或Dmt的酚羟基的O-酰化，也不需要将它们吸收到聚山梨酯包被的纳米颗粒上以诱导通过BBB的摄取。 对一组含有Dmt代替内吗啡肽-1和-2中Tyr的μ阿片样物质的研究揭示了它们的作用模式的差异，这也有助于区分这些结构上相关的化合物。虽然这两种化合物都表现出有效的镇痛作用，但它们的作用方式和镇痛程度明显不同。Dmt在体外和体内均使所有测得的活性参数提高了几个数量级。

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.