Glutamatergic compounds for treating drug addiction: Preclinical models

用于治疗药物成瘾的谷氨酸化合物：临床前模型

• 批准号: 8736736
• 负责人: Eliot Gardner
• 金额: $ 35.47万
• 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/8736736
• 关键词: AMPA Receptors; Addictive Behavior; Agonist; Animal Model; Attention; Attenuated; Behavior; Benzodiazepines; Biochemical; Biological Assay; Brain; Chemicals; Chronic; Cocaine; Cocaine Dependence; Corpus striatum structure; Cues; Data; Development; Dopamine; Dorsal; Dose; Drug Addiction; Electrical Stimulation of the Brain; Enzymes; Exposure to; Globus Pallidus; Glutamate Carboxypeptidase II; Glutamate Receptor; Glutamates; Goals; Habits; High Pressure Liquid Chromatography; Imidazole; Immunoblotting; Injection of therapeutic agent; Inorganic Sulfates; Intravenous; Laboratory Animals; Laboratory Rat; Measures; Mediating; Metabotropic Glutamate Receptors; Methods; Microdialysis; Microinjections; Motivation; N-acetylaspartylglutamate; Neuropeptides; Neurotransmitters; Nucleus Accumbens; Perfusion; Pharmaceutical Preparations; Polymerase Chain Reaction; Pre-Clinical Model; Prosencephalon; Proteins; Psychological reinforcement; RNA; Rattus; Relapse; Reporting; Research; Research Project Grants; Resistance; Reverse Transcription; Rewards; Role; Sampling; Self Administration; Self-Administered; Stress; System; Techniques; Tetrodotoxin; Unspecified or Sulfate Ion Sulfates; Urea; Western Blotting; Work; addiction; craving; drug seeking behavior; extracellular; fenobam; gamma-Aminobutyric Acid; glutamate receptor subunit 3; in vivo; inhibitor/antagonist; interest; metabotropic glutamate receptor 2; metabotropic glutamate receptor 3; metabotropic glutamate receptor 7; methylserine phosphate; neurotransmission; novel; pinacolyl methylphosphonic acid; pre-clinical; preference; presynaptic; prevent; protective effect; pyridine; receptor

During the reporting period, considerable progress was made on this research project. We and others had previously shown that chronic or repeated cocaine administration produces long-term alterations in glutamate neurotransmission in the brain. We therefore previously studied glutamatergic involvement in addiction by studying mGluR5 glutamate receptor antagonism in animal models relating to addiction. We found that blockade of the mGluR5 glutamate brain receptor by the selective, potent, and systemically-active mGluR5 receptor antagonist MPEP (2-methyl-6-(phenylethynyl)-pyridine) inhibits cocaine self-administration and motivation to self-administer cocaine in laboratory rats. We further found that blockade of the mGluR5 glutamate receptor by MPEP significantly inhibits relapse to drug-seeking behavior triggered by cocaine, but not relapse to drug-seeking behavior triggered by either stress or environmental cues previously paired with drug-taking behavior. Using in vivo brain microdialysis methods, we further found that MPEP has no effect on extracellular levels of the neurotransmitter dopamine in the nucleus accumbens of the limbic forebrain in either drug-naive or cocaine-extinguished rats, suggesting a dopamine-independent mechanism underlying MPEP's actions. In contrast, MPEP (administered either systemically or locally into the nucleus accumbens) elevates extracellular glutamate. Furthermore, MPEP dose-dependently inhibited cocaine-induced increases in nucleus accumbens extracellular glutamate in both drug-naive and cocaine-extinguished rats. These data suggested that alterations in nucleus accumbens glutamate underlie MPEP's actions on cocaine-induced reward and cocaine-triggered relapse to drug-seeking behavior, and confirmed that brain glutamate neurotransmission constitutes an attractive target for potential anti-addiction, anti-craving, anti-relapse medications. We also previously studied NAALADase inhibition in animal models relating to addiction. NAALADase (N-acetylated-alpha-linked-acidic dipeptidase; glutamate carboxypeptidase II) is a brain enzyme which hydrolyzes the endogenous brain neuropeptide NAAG (N-acetyl-aspartyl-glutamate) to glutamate and NAA (N-acetyl-aspartate). NAAG is an endogenous mGluR3 glutamate receptor agonist, which inhibits presynaptic glutamate release. Therefore, studies of NAALADase inhibitors in preclinical animal models relating to addiction are of interest in the search for clinically useful pharmacotherapeutic agents for the treatment of addiction, craving, and relapse. Consequently, we studied the effects of 4 NAALADase inhibitors - 2-PMPA, GPI-5693, GPI-16476, and GPI-16477 - in animal models relating to addiction. We found that all 4 NAALADase inhibitors inhibited cocaine-triggered relapse to cocaine-seeking behavior in laboratory rats who had been pharmacologically detoxified and behaviorally extinguished from their prior intravenous cocaine-taking habits. This protective effect against cocaine-triggered relapse to drug-seeking behavior was blocked by intracerebral microinjections of LY341495, a selective mGluR2/3 receptor antagonist, directly into the nucleus accumbens in the brain. This implicates the mGluR2/3 glutamate receptor of the brain in this anti-addiction action. We further found that the NAALADase inhibitor 2-PMPA significantly inhibits motivation to self-administer cocaine. We further found that 2-PMPA and NAAG significantly inhibit cocaine-enhanced brain-stimulation reward and intravenous cocaine self-administration in laboratory rats, and that 2-PMPA attenuates coaine-enhanced dopamine in the nucleus accumbens - an effect that was prevented by LY341495, implicating the involvement of mGluR2/3 rceptors in these effects. We also studied the effects of AMN082, a selective mGluR7 agonist, on extracellular dopamine, gamma-aminobutyric acid (GABA), and glutamate in the nucleus accumbens of the brain as measured by in vivo brain microdialysis. We found that systemic or intra-accumbens administration of AMN082 dose-dependently lowered extracellular GABA, increased extracellular glutamate, and had no effect on extracellular nucleus accumbens dopamine levels. We found that these effects were blocked by MSOP, a group III-selective mGluR antagonist. Intra-accumbens perfusion of tetrodotoxin (TTX) blocked the AMN082-induced increases in glutamate, but failed to block the AMN082-induced reduction in GABA, suggesting vesicular and non-vesicular GABA origins for these effects, respectively. We also found that intra-accumbens perfusion of the selective GABA-B receptor antagonist 2-hydroxysaclofen not only abolished the enhanced extracellular glutamate produced by AMN082, but actually decreased extracellular glutamate in a TTX-resistant manner. We further found that systemically-administered AMN082 dose-dependently inhibits cocaine-triggered reinstatement of drug-seeking behavior. Intracerebral micro-injections of AMN082 into the nucleus accumbens or ventral pallidum, but not into the dorsal striatum, also inhibited cocaine-triggered relapse to drug-seeking behavior, an effect that was blocked by local intracerebral co-administration of MMPIP, a selective mGluR7 receptor antagonist. Pre-treatment with AMN082 dose-dependently blocked both cocaine-enhanced nucleus accumbens glutamate and cocaine-triggered relapse to drug-seeking behavior, an effect that was blocked by MMPIP or the selective mGluR2/3 receptor antgaonist LY341497. These findings suggest that mGluR7 activation inhibits cocaine-triggered relapse to drug-seeking behavior by a glutamate-mGluR2/3 mechanism in the nucleus accumbens. Such findings suggest a potential utility for mGluR7 receptor agonists for the treatment of cocaine addiction. During the present reporting period, we once again turned our attention to the mGluR5 receptor system in the brain and to the negative allosteric mGluR5 modulator fenobam (1-(3-chlorophenyl)-3-(3-methyl-5-oxo-4H-imidazol-2-yl)urea). Using multiple animal models of addiction, We found that fenobam and fenobam sulfate show the same anti-cocaine efficacy as we had previously seen with the mGluR5 antagonists MPEP and MTEP (see above), but that the non-competitive AMPA receptor antagonist GYKI-52466 (1-(4-Aminophenyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine) does not. In addition, during the present reporting period we studied a novel mGluR5 antagonist, MFZ 10-7, and found that it significantly inhibits cocaine-taking and cocaine-seeking behaviors in laboratory rats. In all, these findings suggest that the glutamate neurotransmitter system in the brain continues to be an appropriate target for the development of potential anti-addiction, anti-craving, and anti-relapse medications.

报告期内，该研究项目取得了较大进展。我们和其他人之前已经证明，长期或重复服用可卡因会导致大脑中谷氨酸神经传递的长期改变。因此，我们之前通过研究与成瘾相关的动物模型中的 mGluR5 谷氨酸受体拮抗作用来研究谷氨酸能与成瘾的关系。我们发现，通过选择性、强效且具有全身活性的 mGluR5 受体拮抗剂 MPEP（2-甲基-6-（苯乙炔基）-吡啶）阻断 mGluR5 谷氨酸脑受体，可抑制实验室大鼠的可卡因自我给药和自我给药可卡因的动机。我们进一步发现，MPEP 阻断 mGluR5 谷氨酸受体可显着抑制由可卡因引发的寻求药物行为的复发，但不会抑制由先前与吸毒行为配对的压力或环境线索引发的寻求药物行为的复发。使用体内脑微透析方法，我们进一步发现 MPEP 对未接受药物或可卡因熄灭的大鼠前脑边缘伏核中神经递质多巴胺的细胞外水平没有影响，表明 MPEP 作用的机制不依赖于多巴胺。相比之下，MPEP（全身或局部注射到伏隔核）会升高细胞外谷氨酸。此外，在未接受药物的大鼠和可卡因熄灭的大鼠中，MPEP 剂量依赖性地抑制可卡因诱导的伏核细胞外谷氨酸的增加。这些数据表明，伏隔核谷氨酸的改变是 MPEP 对可卡因诱导的奖赏和可卡因触发的药物寻求行为复发的作用的基础，并证实大脑谷氨酸神经传递构成潜在的抗成瘾、抗渴望、抗复发药物的有吸引力的靶点。我们之前还研究了与成瘾相关的动物模型中的 NAALADase 抑制。 NAALADase（N-乙酰化-α-连接酸性二肽酶；谷氨酸羧肽酶 II）是一种脑酶，可将内源性脑神经肽 NAAG（N-乙酰-天冬氨酰-谷氨酸）水解为谷氨酸和 NAA（N-乙酰-天冬氨酸）。 NAAG 是一种内源性 mGluR3 谷氨酸受体激动剂，可抑制突触前谷氨酸释放。因此，在与成瘾相关的临床前动物模型中对 NAALADase 抑制剂的研究对于寻找临床上有用的药物治疗剂来治疗成瘾、渴望和复发很有意义。因此，我们研究了 4 种 NAALADase 抑制剂 - 2-PMPA、GPI-5693、GPI-16476 和 GPI-16477 - 在与成瘾相关的动物模型中的作用。我们发现，所有 4 种 NAALADase 抑制剂都能抑制实验室大鼠由可卡因引发的可卡因寻求行为的复发，这些大鼠已通过药物解毒并在行为上消除了先前静脉注射可卡因的习惯。这种针对可卡因引发的寻药行为复发的保护作用被脑内微量注射 LY341495（一种选择性 mGluR2/3 受体拮抗剂）直接注射到大脑伏隔核中所阻断。这表明大脑的 mGluR2/3 谷氨酸受体参与了这种抗成瘾作用。我们进一步发现 NAALADase 抑制剂 2-PMPA 显着抑制自我服用可卡因的动机。我们进一步发现，2-PMPA 和 NAAG 显着抑制实验室大鼠中可卡因增强的大脑刺激奖赏和静脉注射可卡因自我给药，并且 2-PMPA 减弱伏隔核中可卡因增强的多巴胺 - 这种作用被 LY341495 阻止，表明 mGluR2/3 受体参与了这些作用。我们还通过体内脑微透析测量了 AMN082（一种选择性 mGluR7 激动剂）对大脑伏核细胞外多巴胺、γ-氨基丁酸 (GABA) 和谷氨酸的影响。我们发现全身或伏隔核内施用 AMN082 剂量依赖性地降低细胞外 GABA，增加细胞外谷氨酸，并且对细胞外伏隔核多巴胺水平没有影响。我们发现这些效应被 MSOP（一种 III 族选择性 mGluR 拮抗剂）阻断。伏隔内灌注河豚毒素 (TTX) 可阻断 AMN082 诱导的谷氨酸增加，但未能阻断 AMN082 诱导的 GABA 减少，表明这些效应分别源自囊泡和非囊泡 GABA。我们还发现，伏隔内灌注选择性 GABA-B 受体拮抗剂 2-羟基萨克洛芬不仅消除了 AMN082 产生的增强的细胞外谷氨酸，而且实际上以 TTX 抗性方式减少了细胞外谷氨酸。我们进一步发现，全身给药 AMN082 剂量依赖性地抑制可卡因触发的寻药行为的恢复。将 AMN082 脑内微量注射到伏隔核或腹侧苍白球，但不注射到背侧纹状体，也抑制了可卡因引发的寻药行为复发，这种作用被局部脑内联合施用 MMPIP（一种选择性 mGluR7 受体拮抗剂）所阻断。 AMN082 预处理剂量依赖性地阻断可卡因增强的伏核谷氨酸和可卡因触发的寻药行为复发，这种作用被 MMPIP 或选择性 mGluR2/3 受体拮抗剂 LY341497 阻断。这些发现表明，mGluR7 激活通过伏隔核中的谷氨酸-mGluR2/3 机制抑制可卡因引发的寻药行为复发。这些发现表明 mGluR7 受体激动剂在治疗可卡因成瘾方面具有潜在用途。在本报告期内，我们再次将注意力转向大脑中的 mGluR5 受体系统和负变构 mGluR5 调节剂非诺班（1-(3-氯苯基)-3-(3-甲基-5-氧代-4H-咪唑-2-基)脲）。使用多种成瘾动物模型，我们发现非诺安和硫酸非诺安表现出与我们之前使用 mGluR5 拮抗剂 MPEP 和 MTEP（见上文）相同的抗可卡因功效，但非竞争性 AMPA 受体拮抗剂 GYKI-52466 （1-（4-氨基苯基）-4-甲基-7,8-亚甲二氧基-5H-2,3-苯二氮卓）则不然。此外，在本报告期内，我们研究了一种新型 mGluR5 拮抗剂 MFZ 10-7，发现它能显着抑制实验室大鼠吸食可卡因和寻求可卡因的行为。总而言之，这些发现表明大脑中的谷氨酸神经递质系统仍然是开发潜在的抗成瘾、抗渴望和抗复发药物的合适目标。