Functional Interactions of Mu and Delta Opioid Receptors

描述（由申请人提供）：阿片类药物（如吗啡）通常用于中度至重度疼痛，然而，其欣快特性导致其广泛滥用。该β-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，并已被建议减弱β-激动剂的一些负面作用。例如，消除d -受体的作用会阻断啮齿动物对吗啡的耐受性和依赖性。这种相互作用可以解释为异源二聚体的？和d受体，或通过区室化成膜微区，如脂筏，形成功能性信号复合物。为了支持这一点，和D受体共定位于某些脑神经元中，并且在生物化学测定中可以异源二聚化，而N和K受体定位于具有功能性信号传导结果的脂筏。该提议的假设是，脂筏是包括串扰在内的D -阿片受体药理学所需的。为了检验这一假设，设计了两个具体目标。具体目标#1的目标是通过解决以下问题来研究脂筏对<$p和d受体信号传导的作用：a）<$p和d受体及其相关信号蛋白定位于脂筏吗？和B）脂筏是否需要有效的信号传导和d受体以及这些受体之间的串扰？目的1中的所有实验将在表达表位标记的受体和/或受体d的HEK 293细胞中进行。具体目标#2的目的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中的<$d和dagoinst-mediated抗伤害感受、耐受性和依赖性，确定降胆固醇对<$d/ d受体相互作用的体内影响。降低胆固醇对阿片类信号传导的影响将提供对D和D受体之间串扰背后机制的深入了解。这种理解可能会导致开发高度有效的镇痛剂，减少滥用的责任。一般来说，由于降胆固醇药物的使用越来越多，临床胆固醇目标不断降低，因此研究降胆固醇对阿片类药物和GPCR信号传导的影响很重要。

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.