Bioactivity Of Neuropeptides

工作概述：最近开发的阿片样物质的药理和生理活性在小鼠体内测定，与吗啡比较，并使用一般和特定的阿片拮抗剂来评估其作用方式。抗痛感谱与使用豚鼠回肠和小鼠输精管测定系统的体外功能药理学数据相似，并反映了受体结合亲和力（参见先前的项目，详细了解肽与-和-阿片受体的相互作用）。一系列新型含有dmt的吡嗪酮类阿片模拟化合物在体内具有特殊的活性，其中一种在体外注射后使用标准测试程序产生镇痛效果比吗啡强60至71倍，但取决于测试是否测量脊柱或脊柱上的作用；前者比后者更有效。特别是，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 mu = 0.02 nM），选择性（δ /mu = 1520）和激动剂活性（GPI, IC50 = 1.7 nM），在所有检测系统中对δ受体的活性都很弱。该化合物主要通过mu-2受体亚型脊髓抗痛觉作用产生脊髓抗痛觉；然而，mu-1亚型在脊柱上占主导地位。sc注射产生中枢神经系统介导的抗痛觉作用，证明该化合物可以通过胃肠道和大脑微细毛细血管紧密连接的膜屏障。然而，一周后获得的耐受性与吗啡相当，这表明两种物质通过类似的机制作用于mu-阿片受体。

Summary of Work: The pharmacological and physiological activity of recently developed opioid mimetic substances were determined in vivo using mice in comparion to morphine and using general as well as specific opiate antagonists to assess their mode of action. The antinociception profile paralled that of the in vitro functional pharmacological data using guinea-pig ileum and mouse vas deferens assay systems, and reflected the receptor binding affinity (see previous projects for details on the interaction of peptides with delta- and mu-opioid receptors). A series of novel Dmt-containing pyrazinone opioid mimetic compounds had exceptional activity in vivo, one of which was 60- to 71-fold more potent than morphine in generating analgesia using standard testing procedures after i.c.v. administration, but depending on whether the test measured spinal or supraspinal effects; the former being more potent than the latter. In particular, the compound 3-[4'-Dmt-aminobutyl)-6-(3'-Dmt-aminopropyl0-5-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 memrane barriers in both the gastrointestinal tract and in the microcapillary tight junctions in the brain. However, a tolerance was obtained after a week that was equivalent to morphine that 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.