Functional Interactions of Mu and Delta Opioid Receptors

描述（由申请人提供）：阿片类药物如吗啡被广泛用于治疗中度至重度疼痛，然而，它们的欣快特性导致了它们的广泛滥用。-阿片受体主要负责镇痛和欣快作用，而d -阿片受体的激动剂保留了一些镇痛特性，但具有较低的滥用倾向，并且被认为可以减轻激动剂的一些负面作用。例如，消除d受体的作用会阻碍啮齿动物对吗啡的耐受性和依赖性的发展。这种相互作用可以解释为¿和d受体的异二聚化，或通过区隔进入膜微域，如脂筏，形成功能性信号复合物。为了支持这一观点，在生化分析中，n和K受体共定位于特定的大脑神经元，可以异二聚，而n和K受体定位于脂质筏，具有功能信号传导后果。这个提议的假设是脂筏是必需的-阿片受体药理学，包括串扰。为了验证这一假设，设计了两个具体的目标。具体目标#1的目标是通过解决以下问题来研究脂筏对¿和d受体信号传导的作用：a)¿和d受体及其相关信号蛋白是否定位于脂筏？b)脂筏是否需要有效的信号传导和d受体之间的相互作用？目的1中的所有实验将在表达表位标记的¿和/或d受体的HEK293细胞中进行。特定目标#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的¿和agoins介导的抗刺激、耐受性和依赖性，确定降胆固醇对体内¿/ d受体相互作用的影响。降低胆固醇对阿片信号传导的影响将有助于深入了解阿片受体和阿片受体之间相互作用的机制。这种理解可能导致高效镇痛药的发展与减少滥用的责任。一般来说，由于降胆固醇药物使用的增加和临床胆固醇目标的不断降低，研究降胆固醇对阿片类药物和GPCR信号的影响是很重要的。

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.