Mixed NOP/mu compounds and the involvement of their receptors in analgesia.

说明(申请人提供)：伤害素/孤啡肽FQ，阿片肽家族的多肽，NOP受体的内源性配体，广泛分布于大脑，参与大量的生理过程。在涉及伤害性反应的脑区、脊髓背角和背根神经节中的高表达水平强烈地表明这是疼痛治疗的靶点。然而，在急性疼痛的啮齿动物模型中，激动剂和拮抗剂似乎都没有显著的抗伤害性。不使用选择性NOP受体激动剂或拮抗剂，一种选择是使用混合的NOP/Mu受体激动剂，基于NOP激动剂减弱由Mu受体激活介导的奖赏和耐受发展的能力。这类化合物，如SR14150，已被证明具有抗伤害感受活性，而不会诱导条件性位置偏爱。此外，最近的实验表明，NOP激动剂在慢性疼痛模型中具有抗痛觉异常的活性，并表明选择性NOP激动剂作为慢性疼痛的治疗药物而不是急性疼痛的潜力要大得多。具体目标1中描述的实验将测试NOP受体和/或N/OFQ在脊髓神经结扎(SNL)或糖尿病神经病变(导致慢性疼痛)大鼠的特定脑区、脊髓和DRG中上调的假设。这将通过定量逆转录聚合酶链式反应检测基因水平，通过蛋白质分析检测蛋白质，通过检测SNL、糖尿病和对照组大鼠脑区和脊髓中[35S]GTP S的结合，以及通过测定静脉注射后一氧化氮合酶激动剂的抗痛觉异常活性来检验。和IT。SNL、糖尿病大鼠和正常大鼠给药。具体目标2将确定NOP激动剂的作用是由于选择性抑制C纤维还是A初级传入。使用高或低的加热率，C-或A-纤维可以被单独激活。此外，SNL和糖尿病神经病变诱导了这些传入的不同敏感性。为了更好地了解这些化合物减轻C和A纤维超敏反应的能力，也为了更好地了解NOP激动剂对不同慢性疼痛状态的潜在临床用途，将测定NOP激动剂阻断机械性异位痛觉、冷性异位痛觉和热痛敏的能力。最后，将针对特定目的合成新的丁丙诺啡类似物3。这些化合物将被设计为具有比丁丙诺啡更高的NOP亲和力和活性，以降低成瘾倾向，从而改善丁丙诺啡作为止痛剂的副作用，并可能作为药物滥用药物。这些化合物以及其他NOP/MU混合化合物将在体外表征结合亲和力和内在活性，在体内表征抗伤害活性和滥用潜力。这些实验将极大地提高对NOP活性化合物介导抗伤害性或抗痛觉过敏反应的机制的理解，并使选择性NOP激动剂和NOP/MU混合激动剂在降低成瘾倾向的临床应用中取得进展。

DESCRIPTION (provided by applicant): Nociceptin/Orphanin FQ, the peptide in the opioid peptide family, and the endogenous ligand for the NOP receptor is widely distributed in the brain and involved in a large number of physiological processes. The high expression level in brain regions involved in nociceptive responses, the dorsal horn of the spinal cord, and dorsal root ganglion has strongly suggested this as a target for pain therapeutics. Nevertheless, neither agonists nor antagonists appear to have significant antinociceptive properties in rodent models of acute pain. Rather than using selective NOP receptor agonists or antagonists, one option would be to use a mixed NOP/mu receptor agonist, based upon the ability of NOP agonists to attenuate reward and tolerance development mediated by mu-receptor activation. Such compounds, such as SR14150, have been demonstrated to have antinociceptive activity without inducing a conditioned place preference. In addition, recent experiments have indicated that NOP agonists have anti-allodynic activity in chronic pain models and suggested a far greater potential for selective NOP agonists as a therapeutic for chronic rather than acute pain. The experiments described in Specific Aim 1 will test the hypothesis that NOP receptors and/or N/OFQ are upregulated in selected brain regions, spinal cord, and DRG of rats subjected to spinal nerve ligation (SNL) or diabetic neuropathy, inducing chronic pain. This will be examined by measuring mRNA level by quantitative rtPCR, and protein by Western analysis, by measuring [35S]GTP S binding in brain regions and spinal cord in SNL, diabetic, and control rats, and by determining the potency of NOP agonists for anti-allodynic activity after i.c.v. and i.t. administration in SNL, diabetic and control rats. Specific Aim 2 will determine whether the actions of NOP agonists are due to selective inhibition of C-fiber or A primary afferents. Using high or low heating rates C- or A -fibers can be independently activated. In addition, SNL and diabetic neuropathy induce differential sensitivity of these afferents. The ability of NOP agonists to block mechanical allodynia, cold allodynia, and thermal hyperalgesia will be determined to better understand both the ability of these compounds to attenuate the hypersensitivity of C- and A -fibers and also to better understand the potential clinical usefulness of NOP agonists for different chronic pain states. Finally, novel buprenorphine analogs will be synthesized for Specific Aim 3. These compounds will be designed to have higher NOP affinity and activity than buprenorphine to decrease the addiction liability and thus improve upon side effect profile of buprenorphine as an analgesic, and potentially as a drug abuse medication. These compounds, as well as other mixed NOP/mu compounds will be characterized in vitro for binding affinity and intrinsic activity, and in vivo for antinociceptive activity and abuse potential. These experiments will provide a greatly improved understanding of the mechanism by which NOP-active compounds mediate an antinociceptive or anti-allodynic response, and progress selective NOP agonists, and mixed NOP/mu agonists toward clinical use as analgesics with reduced addiction liability.