Basic brain mechanisms underlying drug addiction, craving, and relapse

药物成瘾、渴望和复发的基本大脑机制

• 批准号: 10701543
• 负责人: Eliot Gardner
• 金额: $ 167.03万
• 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/10701543
• 关键词: AMPA Receptors; Addictive Behavior; Adrenergic Agents; Agonist; Animal Model; Animals; Antisense Oligonucleotides; Astrocytes; Atenolol; Attenuated; Behavior; Behavioral; Biochemical; Biological Assay; Biological Models; Brain; Brain region; CNR1 gene; CNR2 gene; Cannabinoids; Cocaine; Cocaine Dependence; Cocaine use disorder; Corpus striatum structure; Cues; Cyclic AMP; DARPP; Development; Dopamine; Dopamine D1 Receptor; Dopamine D2 Receptor; Dorsal; Dose; Down-Regulation; Drug Addiction; Electrical Stimulation of the Brain; Exercise; Exposure to; FOS gene; Female; GHS-R1a; Gastric Inhibitory Polypeptide; Gene Expression; Globus Pallidus; Glutamate Transporter; Glutamates; Goals; Heroin; High Pressure Liquid Chromatography; Image; Incentives; Injections; Insulin; Intravenous; Knock-out; Laboratory Animals; Maintenance; Medial; Mediating; Messenger RNA; Microdialysis; Microglia; Microinjections; Midbrain structure; Motivation; Mus; N-Methylaspartate; Neocortex; Neurons; Nucleus Accumbens; Opioid; Optics; Oral; Oxycodone; Pathway interactions; Peripheral; Pharmaceutical Preparations; Pharmacology; Physical Exercise; Plasma; Play; Polymerase Chain Reaction; Process; Proteins; Psychological reinforcement; RNA; Rattus; Recording of previous events; Red nucleus structure; Relapse; Reporting; Research; Reverse Transcription; Rewards; Role; Running; Sampling; Self Administration; Signal Transduction; Somatotropin; Spleen; Stimulus; Stress; Sucrose; System; Techniques; Testing; Therapeutic; Time; Transgenic Organisms; Up-Regulation; Ventral Tegmental Area; Western Blotting; Work; Yohimbine; addiction; antagonist; cell type; cocaine exposure; cocaine self-administration; conditioned place preference; craving; des-n-octanoyl ghrelin; dopaminergic neuron; drug reward; drug seeking behavior; endocannabinoid signaling; extracellular; gamma-Aminobutyric Acid; ghrelin; ghrelin receptor; in vivo; inhibitor; insight; interest; mRNA Expression; male; mesolimbic system; motivated behavior; neural; novel; opioid use disorder; optogenetics; phosphoprotein 32; pre-clinical; receptor; response

During the present reporting period, we continued our prior work on cannabinoids and endocannabinoid signaling in the brain. We previously reported that cocaine self-administration upregulates cannabinoid CB2R expression in midbrain dopamine (DA) neurons. We now investigated whether cocaine or heroin also alters CB2R expression in striatal medium-spiny neurons that express dopamine D1 or D2 receptors (D1-MSNs, D2-MSNs) and microglia. We found that a single injection of cocaine failed to alter, while repeated cocaine injections or self-administration dose-dependently upregulated CB2R gene expression in neocortex, striatum, and periphery (spleen). In contrast, repeated heroin administration produced dose-dependent reduction in striatal CB2 mRNA expression. We found that CB2R upregulation occurred mainly in D1-MSNs, not in D2-MSNs or microglia, in the nucleus accumbens rather than the dorsal striatum. These findings indicate that repeated cocaine exposure may upregulate CB2R expression in both brain and spleen, with regional and cell type-specific profiles. In striatum, CB2R upregulation occurs mainly in D1-MSNs in the nucleus accumbens. Given the important role of D1-MSNs in brain reward function, these findings provide new insight into mechanisms by which brain CB2Rs modulate cocaine action. Glutamate plays an important role in drug-induced and cue-induced reinstatement of drug seeking. But the role of glutamate in drug reward itself is unclear. We therefore studied the effects of multiple glutamate transporter (GLT) inhibitors on extracellular glutamate and dopamine (DA) in the nucleus accumbens (NAc), i.v. cocaine self-administration, intracranial brain-stimulation reward (BSR), and reinstatement of cocaine seeking in male and female rats. Among the five GLT inhibitors tested, TFB-TBOA was the most potent. Microinjections of TFB-TBOA into NAc, but not ventral tegmental area (VTA) or dorsal striatum (DS), dose-dependently inhibited cocaine self-administration under fixed-ratio and progressive-ratio (PR) reinforcement, shifted the cocaine dose-response curve downward, and inhibited intracranial BSR. Selective downregulation of astrocytic GLT-1 expression in the NAc by GLT-1 antisense oligonucleotides also inhibited cocaine self-administration. The reduction in cocaine self-administration following TFB-TBOA administration was NMDA GluN2B receptor dependent, and rats self-administering cocaine showed upregulation of GluN2B expression in NAc DA- and cAMP-regulated phosphoprotein 32 (DARPP-32)-positive medium-spiny neurons (MSNs). In contrast, TFB-TBOA, when locally administered into the NAc, VTA, or ventral pallidum (VP) dose-dependently reinstated cocaine-seeking behavior. Intra-NAc TFB-TBOA-evoked drug-seeking was long-lasting and NMDA/AMPA receptor dependent. These findings, for the first time, indicate that glutamate in the NAc negatively regulates cocaine's rewarding effects, while an excess of glutamate in multiple brain regions triggers reinstatement of drug-seeking behavior. We also explored the role(s) of ghrelin in cocaine addiction. We showed that: (1) elevation of ghrelin by cocaine plays a critical role in maintenance of cocaine self-administration and cocaine-seeking motivated by cocaine-conditioned stimuli; (2) acquisition of cocaine-taking behavior is associated with the acquisition of stimulatory effects of cocaine by cocaine-conditioned stimuli on ghrelin secretion, and with an upregulation of VTA ghrelin receptor mRNA levels; (3) blockade of ghrelin signaling by pretreatment with JMV2959, a selective ghrelin receptor antagonist, dose-dependently inhibits reinstatement of cocaine-seeking triggered by either cocaine or yohimbine in behaviorally extinguished animals with a history of cocaine self-administration; (4) JMV2959 pretreatment also inhibits BSR and cocaine-potentiated BSR maintained by optogenetic stimulation of VTA dopamine neurons in DAT-Cre mice; (5) blockade of peripheral adrenergic 1 receptors by atenolol potently attenuates the elevation in circulating ghrelin induced by cocaine and inhibits cocaine self-administration and cocaine reinstatement triggered by cocaine. However, the response of the ghrelin system to opioid-motivated behaviors and the role of ghrelin in oxycodone self-administration was unstudied. We investigated the reciprocal interactions between the endogenous ghrelin system and oxycodone self-administration behaviors in rats and the role of the ghrelin system in BSR driven by optogenetic stimulation of midbrain reward circuits in mice. Oxycodone self-administration significantly elevated plasma ghrelin, des-acyl ghrelin and growth hormone and showed no effect on plasma LEAP2, a newly identified endogenous ghrelin receptor (GHS-R1a) antagonist. Oxycodone self-administration produced significant decreases in plasma gastric inhibitory polypeptide and insulin. Acquisition of oxycodone self-administration significantly upregulated GHS-R1a mRNA levels in VTA DA neurons. Pretreatment the selective GHS-R1a antagonist JMV29959 dose-dependently reduced oxycodone self-administration and decreased the breakpoint for oxycodone under progressive ratio reinforcement. The inhibitory effects of JMV2959 on oxycodone self-administration is selectively mediated by GHS-R1a as JMV2959 showed a similar effect in Wistar wildtype but not in GHS-R knockout rats. JMV2959 pretreatment significantly inhibited BSR driven by selective stimulation of VTA DA neurons, but not by stimulation of striatal GABA neurons projecting to the VTA in mice. These findings suggest that elevation of ghrelin signaling by oxycodone or oxycodone-associated stimuli is a causal process by which oxycodone motivates oxycodone drug-taking and targeting the ghrelin system may be a viable treatment approach for opioid use disorders in addition to cocaine use disorder. Furthering our cannabinoid work, we explored the therapeutic potential of PIMSR, a neutral CB1R antagonist lacking an inverse agonist profile, against cocaine's behavioral effects. We found that systemic administration of PIMSR dose-dependently inhibited cocaine self-administration under fixed-ratio 5 (FR5), but not FR1, reinforcement, shifted the cocaine self-administration dose-response curve downward, decreased incentive motivation to seek cocaine under progressive-ratio reinforcement, and reduced cue-induced reinstatement of cocaine seeking. PIMSR also inhibited oral sucrose self-administration. Importantly, PIMSR alone is neither rewarding nor aversive as assessed by place conditioning. We then used BSR to explore the possible involvement of the mesolimbic DA system in PIMSR's action. We found that PIMSR dose-dependently attenuated cocaine-enhanced electrical BSR, but by itself failed to alter electrical BSR, while dose-dependently inhibiting BSR maintained by optical stimulation of midbrain DA neurons in transgenic DAT-Cre mice, suggesting the involvement of DA-dependent mechanisms. We also found that PIMSR pretreatment attenuated THC- or ACEA (selective CB1R agonist)-induced reduction in optical BSR. The neutral CB1R antagonist PIMSR deserves further research as a promising pharmacotherapeutic for cocaine use disorder. Finally, we found that long-term physical exercise produced a robust increase in red nucleus c-fos expression, and activates a subset of medial red nucleus (RNm) glutamate neurons projecting to VTA DA neurons. Optogenetic stimulation of this pathway was rewarding, as assessed by BSR and conditioned place preference. Running wheel access decreased cocaine self-administration and cocaine-seeking. Optogenetic stimulation of the RNm-to-VTA glutamate pathway inhibited responding to cocaine. These findings indicate that physical exercise activates a specific RNm-VTA glutamatergic pathway, producing exercise reward and reducing cocaine's appeal.

在本报告所述期间，我们继续进行先前关于大麻素和内源性大麻素在大脑中的信号传导的工作。我们之前报道过，可卡因自我给药上调中脑多巴胺（DA）神经元中大麻素CB2R的表达。我们现在研究了可卡因或海洛因是否也会改变表达多巴胺D1或D2受体（D1- msns, D2- msns）和小胶质细胞的纹状体中棘神经元的CB2R表达。我们发现，单次注射可卡因不能改变CB2R基因的表达，而反复注射可卡因或自我给药则会以剂量依赖的方式上调新皮质、纹状体和外周（脾脏）的CB2R基因表达。相反，重复海洛因给药使纹状体CB2 mRNA表达呈剂量依赖性降低。我们发现CB2R上调主要发生在d1 - msn中，而不是d2 - msn或小胶质细胞，在伏隔核而不是背纹状体中。这些发现表明，反复的可卡因暴露可能上调脑和脾脏中CB2R的表达，并具有区域和细胞类型特异性。在纹状体中，CB2R上调主要发生在伏隔核d1 - msn中。考虑到D1-MSNs在脑奖励功能中的重要作用，这些发现为脑CB2Rs调节可卡因作用的机制提供了新的见解。谷氨酸在药物诱导和线索诱导的药物寻找恢复中起重要作用。但谷氨酸在药物奖励中的作用尚不清楚。因此，我们研究了多种谷氨酸转运蛋白（GLT）抑制剂对雌雄大鼠伏隔核（NAc）细胞外谷氨酸和多巴胺（DA）的影响，静脉注射可卡因自我给药，颅内脑刺激奖励（BSR）和恢复可卡因寻求。在测试的五种GLT抑制剂中，TFB-TBOA是最有效的。将TFB-TBOA显微注射到NAc，但不注射到腹侧被盖区（VTA）或背侧纹状体（DS），剂量依赖性地抑制固定比和递进比（PR）强化下的可卡因自我给药，使可卡因剂量反应曲线向下移动，抑制颅内BSR。GLT-1反义寡核苷酸选择性下调NAc星形细胞GLT-1表达也抑制可卡因自我给药。TFB-TBOA给药后可卡因自我给药的减少是NMDA GluN2B受体依赖的，自我给药的大鼠在NAc DA-和camp调节的磷酸化蛋白32 （DARPP-32）阳性中棘神经元（MSNs）中GluN2B表达上调。相反，当局部给药到NAc、VTA或腹侧白质（VP）时，TFB-TBOA剂量依赖性地恢复了可卡因寻求行为。nac内tfb - tboa诱发的药物寻找是持久的，并且依赖于NMDA/AMPA受体。这些发现首次表明，NAc中的谷氨酸对可卡因的奖赏效应起负调节作用，而大脑多个区域中过量的谷氨酸会引发寻求毒品行为的恢复。我们还探讨了胃饥饿素在可卡因成瘾中的作用。研究结果表明：(1)可卡因对胃饥饿素的升高在维持可卡因自我给药和可卡因条件刺激下的可卡因寻求中起关键作用；(2)可卡因吸食行为的习得性与可卡因条件刺激对胃饥饿素分泌的习得性有关，并与VTA胃饥饿素受体mRNA水平上调有关；(3)选择性胃饥饿素受体拮抗剂JMV2959预处理阻断胃饥饿素信号，剂量依赖性地抑制有可卡因自我给药史的行为消失动物因可卡因或育亨宾触发的可卡因寻求恢复；(4) JMV2959预处理还能抑制DAT-Cre小鼠的BSR和通过光遗传刺激VTA多巴胺神经元维持的可卡因增强BSR；(5)阿替洛尔阻断外周肾上腺素能1受体可有效降低可卡因诱导的循环胃饥饿素升高，抑制可卡因引起的可卡因自我给药和可卡因恢复。然而，胃饥饿素系统对阿片类动机行为的反应以及胃饥饿素在羟考酮自我给药中的作用尚未得到研究。我们研究了大鼠内源性胃饥饿素系统与羟考酮自我给药行为之间的相互作用，以及胃饥饿素系统在光遗传刺激小鼠中脑奖励回路驱动的BSR中的作用。羟可酮自我给药可显著提高血浆胃饥饿素、去酰基胃饥饿素和生长激素水平，而对血浆LEAP2（一种新发现的内源性胃饥饿素受体（GHS-R1a）拮抗剂）无影响。羟考酮自我给药可显著降低血浆胃抑制多肽和胰岛素。羟考酮自我给药可显著上调VTA DA神经元中GHS-R1a mRNA水平。选择性GHS-R1a拮抗剂JMV29959的预处理剂量依赖性地减少了羟考酮的自我给药，并降低了羟考酮在渐进比例强化下的断点。JMV2959对羟考酮自我给药的抑制作用是由GHS-R1a选择性介导的，因为JMV2959在Wistar野生型大鼠中表现出类似的抑制作用，而在GHS-R敲除大鼠中则没有。JMV2959预处理可显著抑制选择性刺激VTA DA神经元驱动的BSR，但对纹状体GABA神经元向VTA投射的刺激无明显抑制作用。这些发现表明，羟考酮或羟考酮相关刺激引起的胃饥饿素信号的升高是一个因果过程，通过这个过程，羟考酮激发了羟考酮药物的服用，并且靶向胃饥饿素系统可能是除可卡因使用障碍外阿片类药物使用障碍的一种可行的治疗方法。进一步我们的大麻素工作，我们探索了PIMSR的治疗潜力，PIMSR是一种中性CB1R拮抗剂，缺乏反向激动剂的特征，可以对抗可卡因的行为影响。我们发现，在固定比5 （FR5）强化下，全身给药PIMSR剂量依赖性地抑制可卡因自我给药，但不抑制FR1强化，使可卡因自我给药剂量-反应曲线向下移动，降低了在递进比强化下寻求可卡因的动机，减少了线索诱导的可卡因寻求的恢复。PIMSR也抑制口服蔗糖自我给药。重要的是，根据场所条件作用的评估，PIMSR本身既没有回报，也没有厌恶。然后，我们使用BSR来探索中边缘DA系统在PIMSR作用中的可能参与。我们发现，PIMSR剂量依赖性地减弱了可卡因增强的电BSR，但其本身不能改变电BSR，而在转基因DAT-Cre小鼠中，PIMSR通过光刺激中脑DA神经元来维持BSR，剂量依赖性地抑制了BSR，这表明参与了DA依赖机制。我们还发现，PIMSR预处理可以减弱THC-或ACEA（选择性CB1R激动剂）诱导的光学BSR的降低。中性CB1R拮抗剂PIMSR作为一种有前景的药物治疗可卡因使用障碍值得进一步研究。最后，我们发现长期体育锻炼可显著增加红核c-fos表达，并激活内侧红核（RNm）谷氨酸神经元向VTA DA神经元的投射。通过BSR和条件位置偏好来评估，光遗传刺激该途径是有益的。跑步轮减少了可卡因的自我服用和可卡因寻找。光遗传刺激rnm - vta谷氨酸通路抑制对可卡因的反应。这些发现表明，体育锻炼激活了特定的RNm-VTA谷氨酸能通路，产生运动奖励，降低可卡因的吸引力。