Endocannabinoid roles in neurochemical and reinforcing effects of abused drugs

内源性大麻素在神经化学中的作用和增强滥用药物的作用

• 批准号: 10004430
• 负责人: Gianluigi Tanda
• 金额: $ 66.11万
• 依托单位: NATIONAL INSTITUTE ON DRUG ABUSE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10004430
• 关键词: 2-arachidonylglycerol; AM404; Acids; Acute; Agonist; Agreement; Amphetamines; Animal Model; Animals; Area; Astrocytes; Attenuated; Autoreceptors; Behavior; Behavioral; Brain; CB1 receptor antagonist; CNR1 gene; Cannabinoids; Cannabis; Cholinergic Antagonists; Chronic; Cocaine; Cues; DRD2 gene; Discrimination; Dopamine; Drug effect disorder; Electroencephalography; Electrophysiology (science); Endocannabinoids; Enhancers; Enzyme Inhibitor Drugs; Enzymes; Ethanol; FAAH inhibitor; Functional disorder; Glutamates; Heroin; Hour; Human; In Situ Hybridization; In Vitro; Intravenous; Kynurenine; Kynurenine 3-monooxygenase; Ligands; Lipase; Measures; Medial; Mediating; Mental disorders; Messenger RNA; Metabolic; Metabolism; Methamphetamine; Microdialysis; Molecular Conformation; Monkeys; Mus; Naloxone; Negative Finding; Nerve; Neurobiology; Neurodegenerative Disorders; Nicotine; Nicotinic Receptors; Nucleus Accumbens; Opiate Addiction; Opioid; Pathway interactions; Pharmaceutical Preparations; Pharmacology; Pharmacotherapy; Play; Prefrontal Cortex; Procedures; Process; Psychiatric therapeutic procedure; Psychological reinforcement; Quinpirole; Rattus; Reporting; Rewards; Rodent; Role; Saline; Self Administration; Slice; Substance Use Disorder; Testing; Tetrahydrocannabinol; Therapeutic; Time; Training; Variant; Ventral Tegmental Area; Wild Type Mouse; Withdrawal; Withdrawal Symptom; analog; anandamide; brain pathway; cannabinoid drug; cannabinoid receptor; dopaminergic neuron; drug of abuse; drug withdrawal; endogenous cannabinoid system; experimental study; extracellular; fatty acid amide hydrolase; gamma-Aminobutyric Acid; hippocampal pyramidal neuron; in vivo; inhibitor/antagonist; marijuana use disorder; methanandamide; methyllycaconitine; neurobiological mechanism; neurochemistry; neurotransmission; opioid use disorder; opioid withdrawal; preclinical study; preference; prevent; receptor; response; reuptake; rimonabant; side effect

The levels of the endogenous cannabinoid agonist anandamide (AEA) can be stimulated by activation of DA D2R in specific brain areas. For example, drugs of abuse increase extracellular levels of dopamine (DA) leading to activation of DA D2Rs, which in turn may increase AEA levels and activate CB1R. These effects may explain why cocaine, amphetamine, nicotine and the D2/3 DAR agonist quinpirole potentiate the effects of the main psychoactive ingredient in cannabis, THC, in THC-discrimination tests in rats, but they do not produce significant effects when injected alone. Nicotine and the D2/3 DAR agonist quinpirole generalize to the THC cue in animals pretreated with the inhibitor of FAAH that metabolizes AEA. Nicotine and quinpirole also potentiate the discriminative effects of THC. Taken together the results of these experiments suggest that AEA is released by drugs of abuse through activation of a D2R-mediated mechanism. We have discovered that endogenous cannabinoids possess reinforcing effects assessed by self-administration procedures. Also, systemic administration of endogenous cannabinoid agonists would increase extracellular levels of DA. One of these endocannabinoids, 2AG, produces a small, transient increase in DA levels in the nucleus accumbens shell (NAS). This is in agreement with reports showing that 2AG is usually very rapidly metabolized in vivo by a specific enzyme, mono-acyl-glyceryl-lipase (MAGL). We have now available a drug, AM-4301, that would selectively block the activity of the MAGL enzyme. By blocking this enzyme we should be able to potentiate the behavioral and neurochemical effects of 2AG. When tested alone, AM-4301 slightly decreased levels of DA in the shell in rats. When administered in combination with 2AG the results show a larger increase in DA than with 2AG alone. It is interesting to note that our preliminary tests show that AM-4301 might be interacting with the MAGL enzyme with a delayed onset and longer-lasting action. Indeed we found a larger increase in DA after AM-4301 pretreatments in animals injected with 2-AG, when the pretreatment time was 24 hours as compared to 40 or 60 minutes. In a recent study, mice genetically modified to include the human D4.7 variant in the brain D4 receptor have been tested with cocaine and methamphetamine. Results on changes in dopaminergic responses in reward related areas have been evaluated in comparison with wild type mice. Results about stimulation of dopamine levels in the accumbens suggest a possible involvement of glutamate release under control of the D4 receptors. Ongoing studies would test differences in the effects of THC in D4-D4.7 mice compared to wild type. We have started preclinical studies on EEG in rats treated acutely or chronically with drugs abused by humans. We are characterizing the EEG during drug treatment or withdrawal, with and without cannabinoid drug treatments to find pharmacologic therapies that could alleviate/attenuate the strong symptoms of withdrawal, for example in subjects dependent on opioids. The reinforcing effects of THC, the main psychoactive ingredient in cannabis, are likely mediated by activation of specific brain pathways. THC enhances the firing of DA neurons in the ventral tegmental area (VTA), which leads to stimulation of DA release from nerve terminals in the NAC shell. Developing medications that modulate the neurotransmission involved in the reinforcing actions of THC might provide a therapeutic approach for the treatment of cannabis use disorder. Reward-related behavioral and neurochemical effects of THC could be blocked by methyl-lycaconitine (MLA), a selective antagonist of alpha7-nAChRs, expressed by glutamatergic nerve terminals in both the VTA and the NAS. Their activation elicits GLU release activating ionotropic GLUR on DAergic terminals to stimulate DA release. Unfortunately, systemic use of direct antagonists of alpha7-nAChRs is associated with side effects that limit their therapeutic utility. Unwanted effects might be avoided by using endogenous negative allosteric modulators of alfa7nAChRs, like KYNA, which might be better tolerated than directly acting cholinergic antagonists. Allosteric modulators change Rs conformations in the presence of orthosteric ligands and often have no effect on their own. To this end we tested Ro 61-8048, an inhibitor of the KMO enzyme that indirectly increase the endogenous levels of KYNA. Newly formed KYNA, is synthesized by astroglia is promptly released into the extracellular compartment. Notably, no reuptake processes exist for KYNA, and extracellular KYNA is not degraded enzymatically, but is slowly eliminated from the brain by a non-specific acid transporter. In a recent study, we show that the reinforcing effects of THC in rats and monkeys, and the reinforcement-related dopamine-releasing effects of THC in rats, can be attenuated by increasing endogenous levels of KYNA through systemic administration of the kynurenine 3-monooxygenase inhibitor, Ro 61-8048. KYNA is a negative allosteric modulator of 7 nicotinic acetylcholine receptors (7nAChRs) and is synthesized and released by astroglia, which express functional 7nAChRs and CB1Rs. We tested whether these presumed KYNA autoreceptors, 7nAChRs, and CB1Rs regulate glutamate release. We used rat in vivo microdialysis and electrophysiology, RNAscope in situ hybridization in brain slices, and primary culture of rat cortical astrocytes. Acute systemic administration of THC increased extracellular levels of glutamate in the NAS, ventral tegmental area (VTA) and medial prefrontal cortex (mPFC). THC also reduced extracellular levels of KYNA in the NAS. These THC effects were prevented by administration of Ro 61-8048 or the CB1R antagonist, rimonabant. THC increased the firing activity of glutamatergic pyramidal neurons projecting from the mPFC to the NAS or to the VTA in vivo. These effects were prevented by pretreatment with Ro 61-8048. In vitro, THC elicited glutamate release from cortical astrocytes (on which we demonstrated co-localization of the CB1Rs and 7nAChRs mRNAs), and this effect was prevented by KYNA and rimonabant. These results suggest a key role of astrocytes in interactions between the endocannabinoid system, kynurenine pathway and glutamatergic neurotransmission, with ramifications for the pathophysiology and treatment of psychiatric and neurodegenerative diseases.

激活特定大脑区域的 DA D2R 可以刺激内源性大麻素激动剂 anandamide (AEA) 的水平。例如，滥用药物会增加细胞外多巴胺 (DA) 水平，导致 DA D2R 激活，进而可能增加 AEA 水平并激活 CB1R。这些作用可以解释为什么可卡因、安非他明、尼古丁和 D2/3 DAR 激动剂喹吡罗在大鼠 THC 辨别测试中增强大麻中主要精神活性成分 THC 的作用，但单独注射时不会产生显着作用。在用代谢 AEA 的 FAAH 抑制剂预处理的动物中，尼古丁和 D2/3 DAR 激动剂喹吡罗可推广到 THC 信号。尼古丁和喹吡罗也增强了 THC 的歧视作用。总而言之，这些实验的结果表明，滥用药物通过激活 D2R 介导的机制来释放 AEA。 我们发现内源性大麻素具有通过自我给药程序评估的增强作用。此外，全身施用内源性大麻素激动剂会增加细胞外 DA 水平。其中一种内源性大麻素 2AG 可使伏隔核壳 (NAS) 中的 DA 水平小幅短暂增加。这与表明 2AG 通常在体内通过特定酶单酰基甘油脂肪酶 (MAGL) 非常快速地代谢的报道一致。我们现在有一种药物 AM-4301，可以选择性地阻断 MAGL 酶的活性。通过阻断这种酶，我们应该能够增强 2AG 的行为和神经化学效应。单独测试时，AM-4301 略微降低了大鼠壳中的 DA 水平。当与 2AG 联合给药时，结果显示 DA 的增加比单独使用 2AG 更大。有趣的是，我们的初步测试表明 AM-4301 可能与 MAGL 酶相互作用，具有延迟起效和更持久的作用。事实上，我们发现注射 2-AG 的动物经 AM-4301 预处理后，当预处理时间为 24 小时时，DA 比 40 或 60 分钟有更大的增加。 在最近的一项研究中，对经过基因改造、在大脑 D4 受体中包含人类 D4.7 变体的小鼠进行了可卡因和甲基苯丙胺测试。与野生型小鼠相比，评估了奖励相关区域多巴胺能反应变化的结果。关于刺激伏隔核中多巴胺水平的结果表明，可能涉及 D4 受体控制下的谷氨酸释放。正在进行的研究将测试 THC 对 D4-D4.7 小鼠与野生型小鼠的影响的差异。 我们已经开始对接受人类滥用药物急性或长期治疗的大鼠进行脑电图临床前研究。我们正在描述药物治疗或戒断期间的脑电图，无论有或没有大麻素药物治疗，以寻找可以减轻/减弱戒断的强烈症状的药物疗法，例如在依赖阿片类药物的受试者中。 THC（大麻中的主要精神活性成分）的增强作用可能是通过激活特定的大脑通路来介导的。 THC 增强腹侧被盖区 (VTA) DA 神经元的放电，从而刺激 NAC 壳神经末梢释放 DA。开发调节涉及 THC 增强作用的神经传递的药物可能为治疗大麻使用障碍提供一种治疗方法。 THC 的奖赏相关行为和神经化学作用可以被甲基-lycaconitine (MLA) 阻断，MLA 是 α7-nAChR 的选择性拮抗剂，由 VTA 和 NAS 中的谷氨酸能神经末梢表达。它们的激活引起 GLU 释放，激活 DAergic 末端上的离子型 GLUR，以刺激 DA 释放。不幸的是，全身使用 α7-nAChR 直接拮抗剂会产生限制其治疗效用的副作用。通过使用 alfa7nAChR 的内源性负变构调节剂（如 KYNA）可以避免不良影响，它可能比直接作用的胆碱能拮抗剂具有更好的耐受性。变构调节剂在正构配体存在的情况下改变 Rs 构象，并且通常对其自身没有影响。为此，我们测试了 Ro 61-8048，这是一种 KMO 酶抑制剂，可间接增加 KYNA 的内源水平。 新形成的 KYNA 由星形胶质细胞合成，并迅速释放到细胞外室。值得注意的是，KYNA 不存在再摄取过程，并且细胞外 KYNA 不会被酶降解，而是通过非特异性酸转运蛋白从大脑中缓慢消除。 在最近的一项研究中，我们表明，通过全身施用犬尿氨酸 3-单加氧酶抑制剂 Ro 61-8048，增加 KYNA 的内源水平，可以减弱 THC 对大鼠和猴子的增强作用，以及 THC 对大鼠的增强相关多巴胺释放作用。 KYNA 是 7 种烟碱型乙酰胆碱受体 (7nAChR) 的负变构调节剂，由表达功能性 7nAChR 和 CB1R 的星形胶质细胞合成和释放。我们测试了这些假定的 KYNA 自受体、7nAChR 和 CB1R 是否调节谷氨酸释放。我们使用了大鼠体内微透析和电生理学、脑切片中的RNAscope原位杂交以及大鼠皮质星形胶质细胞的原代培养。急性全身施用 THC 会增加 NAS、腹侧被盖区 (VTA) 和内侧前额皮质 (mPFC) 的细胞外谷氨酸水平。 THC 还降低了 NAS 中 KYNA 的细胞外水平。这些 THC 效应可以通过使用 Ro 61-8048 或 CB1R 拮抗剂利莫那班来预防。 THC 增加体内从 mPFC 投射到 NAS 或 VTA 的谷氨酸能锥体神经元的放电活动。使用 Ro 61-8048 进行预处理可以防止这些影响。在体外，THC 引起皮质星形胶质细胞释放谷氨酸（我们证明了 CB1R 和 7nAChR mRNA 的共定位），并且 KYNA 和利莫那班可以阻止这种效应。这些结果表明星形胶质细胞在内源性大麻素系统、犬尿氨酸途径和谷氨酸神经传递之间的相互作用中发挥着关键作用，并对精神和神经退行性疾病的病理生理学和治疗产生影响。