Functional Interactions of Mu and Delta Opioid Receptors

描述(申请人提供)：吗啡等阿片类药物被大量用于中度至重度疼痛，然而，它们的兴奋特性导致了它们的广泛滥用。阿片受体主要负责镇痛和兴奋作用，而d-阿片受体激动剂保留了一些止痛特性，但滥用可能性较低，已被建议用来减轻激动剂的一些负面影响。例如，消除d-受体的作用可以阻止啮齿类动物对吗啡的耐受和依赖。这种相互作用可以通过受体和受体的异源二聚化来解释，或者通过划分成膜微域，如脂筏，形成功能信号复合体来解释。为了支持这一点，受体和d在某些脑神经元中共定位，并在生化分析中可以异二聚体，而n和K受体定位于脂筏，具有功能信号后果。这一建议的假设是，包括串扰在内的阿片受体和d-阿片受体的药理作用需要脂筏。已经设计了两个具体的目标来检验这一假设。具体目标#1的目的是通过解决以下问题来研究脂筏在？和d受体信号转导中的作用：a)？和d受体及其相关信号蛋白是否定位于脂筏？和b)是否需要脂筏来有效地传递？和d受体的信号以及这些受体之间的串扰？目标1中的所有实验都将在表达表位标记的和/或d受体的HEK293细胞中进行。具体目标#2的目标是通过测量临床使用的降胆固醇药物辛伐他汀治疗的小鼠体内降胆固醇对？/d受体相互作用的影响，测量？和dagoinst介导的抗伤害、耐受和依赖性。降低胆固醇对阿片类药物信号的影响将为深入了解受体和D受体之间的串扰机制提供依据。这一认识可能导致开发高效止痛药，减少滥用风险。由于降胆固醇药物的使用日益增多，临床降胆固醇指标不断降低，因此降胆固醇对阿片类药物和GPCR信号转导的影响具有重要的研究意义。

DESCRIPTION (provided by applicant): Opioids such as morphine are highly prescribed for moderate to severe pain, however, their euphoric properties contribute to their widespread abuse. The ¿-opioid receptor is primarily responsible for both the analgesic and euphoric effects, while agonists at the d -opioid receptor retain some analgesic properties, but have a lower abuse liability and have been suggested to attenuate some of the negative effects of ¿ agonists. For instance, eliminating the action of the d -receptor blocks the development of morphine tolerance and dependence in rodents. This interaction could be explained by heterodimerization of ¿ and d receptors, or by compartmentalization into membrane microdomains, such as lipid rafts, to form functional signaling complexes. In support of this, ¿ and d receptors colocalize in certain brain neurons and can heterodimerize in biochemical assays, while n and K receptors localize to lipid rafts with functional signaling consequences. The hypothesis of this proposal is that lipid rafts are required for ¿ and d -opioid receptor pharmacology including cross-talk. Two specific aims have been designed to test this hypothesis. The goal of specific aim #1 is to investigate the role of lipid rafts on ¿ and d receptor signaling by addressing the following questions: a) Are ¿ and d receptors and their associated signaling proteins localized to lipid rafts? and b) Are lipid rafts required for efficient signaling of ¿ and d receptors and for cross-talk between these receptors? All experiments in aim 1 will be performed in HEK293 cells expressing epitope-tagged ¿ and/or d receptors. The goal of specific aim #2 is to determine the impact of cholesterol-lowering on ¿/ d receptor interactions in vivo, by measuring ¿ and d agoinst-mediated antinociception, tolerance and dependence in mice treated with the clinically-used cholesterol-lowering agent simvastatin. The effect of cholesterol-lowering on opioid signaling will provide insight into the mechanism behind the cross-talk between ¿ and d receptors. This understanding could lead to the development of highly efficacious analgesics with a decreased abuse liability. Generally, the effect of cholesterol-lowering on opioid and GPCR signaling is important to study because of the increasing use of cholesterol-lowering agents and the continuously lowering clinical cholesterol goals.