Trek channels and opioid signaling in the ventral tegmental area

腹侧被盖区的 Trek 通道和阿片类信号传导

• 批准号: 8029583
• 负责人: KEVIN D WICKMAN
• 金额: $ 17.68万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8029583
• 关键词: AIDS/HIV problem; Ablation; Acute; Adenylate Cyclase; Adverse effects; Analgesics; Anesthesia procedures; Antibodies; Behavior; Behavioral; Blocking Antibodies; Brain; Cardiovascular system; Cells; Chronic; Cocaine; Communicable Diseases; Complex; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Data; Diagnostic; Disinhibition; Drug Delivery Systems; Epilepsy; Exhibits; GTP-Binding Proteins; Goals; Health; Hepatitis; Heroin; Interneurons; Ion Channel; Knock-out; Knockout Mice; Link; Lung; Measures; Mediating; Mental Depression; Modeling; Molecular; Morphine; Motor; Mus; Neurons; Nociception; Opioid; Opioid Receptor; Outcome Study; Overdose; Pain; Pain management; Pharmaceutical Preparations; Phosphorylation; Physiological; Population; Potassium Channel; Psychological reinforcement; Public Health; Reporting; Reverse Transcriptase Polymerase Chain Reaction; Rewards; Role; Signal Pathway; Signal Transduction; Slice; Spontaneous abortion; Testing; Therapeutic; Up-Regulation; Ventral Tegmental Area; Voltage-Clamp Technics; Work; addiction; base; clinically significant; design; dopaminergic neuron; gamma-Aminobutyric Acid; member; neural circuit; novel; opioid abuse; postsynaptic; public health relevance; relating to nervous system; reward processing

DESCRIPTION (provided by applicant): Opioid-based drugs are mainstays for pain management despite their significant side effects and addictive liability. Abuse of opioid drugs such as heroin is linked to many serious health problems, including fatal overdose, spontaneous abortion, infectious disease such as hepatitis and HIV/AIDS, and cardiovascular and pulmonary problems. Given both their clinical significance and adverse impact on public health, it is imperative that we understand mechanisms underlying the physiological and behavioral effects of opioids. The work proposed herein centers on a key neural substrate of opioid reward - the ventral tegmental area (VTA) - and challenges conventional wisdom concerning the signaling pathway mediating the opioid-induced disinhibition of dopaminergic (DA) neurons, a key mechanism of opioid reward. The opioid-induced disinhibition of DA neurons in the VTA involves the direct hyperpolarization of VTA GABA neurons. G protein-gated inwardly- rectifying K+ (GIRK/KIR3) channels are widely-considered to mediate the opioid-induced hyperpolarization of GABA neurons, due largely to their documented roles in metabotropic postsynaptic inhibition in many neuron populations. Our recent attempt to validate this paradigm failed, however, revealing that GIRK channels do not mediate the inhibition of VTA GABA neurons, the disinhibition of VTA DA neurons, or reward-related behavioral effects of opioids. Instead, our findings suggest that the acute inhibitory actions of opioids on VTA GABA neurons are mediated by the inhibition of adenylyl cyclase and consequent activation of an ion channel exhibiting the unique regulatory and biophysical signature of the Trek subfamily of 2-pore (K2P) K+ channels. The goal of this study is to test the hypothesis that opioids indirectly stimulate VTA dopamine neurons, and evoke reward-relevant behaviors, by activating Trek channels in VTA GABA neurons. At present, there are scant data concerning Trek expression in the VTA and no reports of Trek channel involvement in opioid signaling. As such, we will begin in AIM 1 by determining whether it is Trek1 or Trek2 that carries the MOR- activated K+ current in VTA GABA neurons. Well-characterized function-blocking antibodies directed against Trek1 and Trek2, as well as single-cell RT-PCR, will be applied to electrophysiological studies involving VTA GABA neurons in slices. In AIM 2, we will use available Trek knockout mice to measure the impact of Trek ablation on opioid signaling in the VTA, and on the motor-stimulatory and reinforcing effects of morphine. In AIM 3, we will seek a better understanding of the novel observation that the MOR-activated K+ current in VTA GABA neurons is significantly enhanced in Girk knockout mice. Electrophysiological and behavioral approaches will be used to probe the relationship between the MOR-activated K+ current in VTA GABA neurons and the complex adaptations linked to chronic drug administration. The proposed work will reframe our understanding of signaling downstream from opioid receptors and as such, may have significant implications for diagnostic or therapeutic strategies relevant to pain management and addiction. PUBLIC HEALTH RELEVANCE: Opioid-based drugs target neural circuitry important for pain processing and reward, actions that explain both their beneficial (analgesic) and untoward (addictive) effects. This proposal challenges conventional wisdom concerning the molecular details of opioid signaling in a key neuron population involved in reward. A clear understanding of the molecular mechanisms of opioid reward is crucial to our understanding of addiction and to the design of more selective and effective therapeutic approaches to pain management.

描述（由申请人提供）：基于阿片类药物的药物是疼痛管理的支柱，尽管其副作用很大和令人上瘾的责任。滥用海洛因等阿片类药物与许多严重的健康问题有关，包括致命的过量，自发流产，肝炎和艾滋病毒/艾滋病等传染病以及心血管和肺部问题。鉴于它们对公共卫生的临床意义和不利影响，我们必须了解阿片类药物生理和行为影响的基础机制。本文提出的工作集中于阿片类药物奖励的关键神经底物 - 腹侧对接区域（VTA），并挑战了传统的智慧，涉及介导阿片类药物诱导的多巴胺能（DA）神经元的抑制的信号通路，这是阿片类奖励的关键机制。阿片类药物诱导的DA神经元在VTA中的抑制作用涉及VTA GABA神经元的直接超极化。 G蛋白门控的内部构建K+（GIRK/KIR3）通道被广泛考虑以介导阿片类药物诱导的GABA神经元的超极化，这主要是由于它们在许多神经元群体中的替代性抑制性抑制作用。然而，我们最近验证这种范式的尝试失败了，表明Girk通道不会介导VTA GABA神经元的抑制作用，对VTA DA神经元的抑制作用或阿片类药物的奖励相关行为效应。取而代之的是，我们的发现表明，阿片类药物对VTA GABA神经元的急性抑制作用是通过抑制腺苷酸环化酶的抑制以及随之而来的激活，并激活了2盘（K2P）K+（K2P）K+（K2P）K+（K2P）k2p）trek trek trek trek trek trek trek的独特调节和生物物理学的信号。频道。这项研究的目的是通过激活VTA GABA神经元中的TREK通道来检验阿片类药物间接刺激VTA多巴胺神经元的假设，并引起与奖励相关的行为。目前，关于VTA中的跋涉表达的数据很少，并且没有跋涉通道参与阿片类药物信号传导的报告。因此，我们将通过确定trek1还是Trek2的trek2开始，它携带VTA GABA神经元中的k+电流。针对TREK1和TREK2的特征障碍抗体以及单细胞RT-PCR将应用于涉及切片中VTA GABA神经元的电生理研究。在AIM 2中，我们将使用可用的跋涉敲除小鼠来测量跋涉消融对VTA中阿片类药物信号的影响以及吗啡的运动刺激和增强作用。在AIM 3中，我们将寻求更好地理解新颖的观察结果，即VTA GABA神经元中的MOR激活的K+电流在Girk敲除小鼠中显着增强。电生理和行为方法将用于探测VTA GABA神经元中Mor激活的K+电流与与慢性药物给药有关的复杂改编之间的关系。拟议的工作将重新构架我们对阿片类药物受体下游信号的理解，因此，可能对与疼痛管理和成瘾有关的诊断或治疗策略具有重要意义。 公共卫生相关性：基于阿片类药物的药物的目标是对疼痛处理和奖励重要的神经回路，解释其有益（镇痛）和不良影响（成瘾性）效果的行为。该提议挑战了有关奖励的关键神经元人群中阿片类药物信号的分子细节的传统观念。对阿片类药物奖励的分子机制的清晰了解对于我们对成瘾的理解以及对疼痛管理的更有选择和有效的治疗方法的设计至关重要。