Mechanisms by which MU Opioid Receptors Resist Desensitization

MU阿片受体抵抗脱敏的机制

• 批准号: 8648572
• 负责人: Reagan Pennock
• 金额: $ 3.3万
• 依托单位: COLORADO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2017-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8648572
• 关键词: Acute; Acute Pain; Agonist; Analgesics; Attenuated; Brain; Chronic; Comparative Study; Complement; Coupled; Coupling; Data; Development; Diffusion; Drug usage; Electrophysiology (science); Environment; Exposure to; Fluorescence Microscopy; Fluorescence Recovery After Photobleaching; Frequencies; Future; G Protein-Coupled Receptor Genes; Individual; Maintenance; Measures; Mediating; Molecular; Neurons; Opioid; Opioid Receptor; Pain; Pathway interactions; Pharmaceutical Preparations; Pharmacology; Phosphorylation; Physiology; Play; Population; Predisposition; Preparation; Presynaptic Receptors; Presynaptic Terminals; Pro-Opiomelanocortin; Property; Protein Kinase; Receptor Signaling; Reporting; Resistance; Role; Signal Transduction; Slice; Solid; Synapses; Testing; Training; Translating; Work; abstracting; base; biophysical properties; career; desensitization; design; gamma-Aminobutyric Acid; insight; mu opioid receptors; neurotransmitter release; particle; platform-independent; postsynaptic; presynaptic; prevent; public health relevance; receptor; receptor coupling; research study; single molecule; tool

DESCRIPTION (provided by applicant): Abstract Opioid based treatments are highly effective at relieving acute pain, but repeated or prolonged use of the drugs results in tolerance to their analgesic effects. Opioid receptor desensitization is an early step in the development of tolerance. Therefore, understanding the mechanisms that govern receptor desensitization is a critical step in designing approaches to reduce desensitization and possibly prevent analgesic tolerance. The work proposed will build on the observation that acute opioid receptor desensitization occurs selectively at somato-dendritic mu opioid receptors (MORs), whereas MORs located on presynaptic terminals of neurons maintain signaling during opioid treatment. Our recent studies provided strong evidence that presynaptic resistance to desensitization is not specific to the MOR but is a property of many inhibitory GPCRs. It is currently unclear whether a property of the receptor or the presynaptic compartment confers resistance to desensitization. The experiments in this proposal will 1) determine how effector coupling and phosphorylation influence a receptor's ability to resist desensitization, and 2) determine whether a receptor's diffusion state is related to its ability to desensitize. Hypopthalamic proopiomelanocortin (POMC) neurons receive inputs that are regulated by MORs and GABAB receptors (GABABRs). MORs presynaptic to POMC neurons are completely resistant to acute desensitization, but approximately ~25% of POMC neurons receive inputs wherein GABABR mediated inhibition of GABA release robustly desensitizes. Using brain slice electrophysiology and pharmacological tools, it will be determined whether this differential desensitization between MORs and GABABRs can be attributed to a particular effector pathway, or if desensitization occurs at the level of the receptor. To determine the role that the diffusion state of the receptor plays in receptor desensitization, single-particle tracking of fluorescently tagged somato-dendritic MORs in cultured neurons will be utilized. It is hypothesized that agonist treatment will alter the mobility of MORs as they undergo desensitization. Differences in diffusion state may be a key factor in differential desensitization of pre- and postsynaptic MORs. The data generated in Aim 2 will provide a platform for future studies investigating presynaptic receptors specifically. Altogether, the data will provide valuable information about the mechanisms underlying resistance to desensitization by presynaptic MORs. Understanding how resistance to desensitization occurs will provide information that may be used in the rational design of new opioid agonists that are both highly efficacious and produce limited tolerance. In performing the proposed experiments the applicant will gain valuable training that will provide a solid platform for an independent scientific career.

描述（由申请人提供）：摘要阿片类药物治疗在缓解急性疼痛方面非常有效，但重复或长期使用这些药物会导致对其镇痛作用的耐受性。阿片受体脱敏是耐受性发展的早期步骤。因此，了解控制受体脱敏的机制是设计减少脱敏和可能防止镇痛耐受的方法的关键步骤。建议的工作将建立在观察急性阿片受体脱敏发生选择性在体细胞树突μ阿片受体（MORs），而MORs位于突触前神经元的终端保持信号在阿片类药物治疗。我们最近的研究提供了强有力的证据表明，突触前对脱敏的抵抗并不是莫尔所特有的，而是许多抑制性GPCR的一种特性。目前还不清楚是否受体或突触前区室的属性赋予抵抗脱敏。本提案中的实验将1）确定效应器偶联和磷酸化如何影响受体抵抗脱敏的能力，以及2）确定受体的扩散状态是否与其脱敏能力相关。下丘脑前阿黑皮素（POMC）神经元接受由MORs和GABAB受体（GABABR）调节的输入。POMC神经元突触前的MOR完全抵抗急性脱敏，但约25%的POMC神经元接受输入，其中GABABR介导的GABA释放抑制强烈脱敏。使用脑切片电生理学和药理学工具，将确定MORs和GABABR之间的这种差异脱敏是否可以归因于特定的效应子途径，或者脱敏是否发生在受体水平。为了确定受体的扩散状态 在受体脱敏中的作用，将利用培养的神经元中荧光标记的体细胞-树突状MORs的单颗粒追踪。据推测，激动剂治疗将 改变MORs的迁移率，因为它们经历脱敏。扩散状态的差异可能是突触前和突触后MORs差异脱敏的关键因素。Aim 2中产生的数据将为未来专门研究突触前受体的研究提供平台。总而言之，这些数据将提供有价值的信息的机制，抵抗脱敏突触前MORs。了解脱敏抵抗是如何发生的，将提供可用于合理设计既高效又产生有限耐受性的新阿片受体激动剂的信息。在执行拟议的实验中，申请人将获得宝贵的培训，这将为独立的科学生涯提供坚实的平台。