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，我们继续之前关于大脑中大麻素和内源性大麻素信号传导的工作。我们之前报道过，自我施用可卡因会上调中脑多巴胺（DA）神经元中大麻素 CB2R 的表达。我们现在研究可卡因或海洛因是否也会改变表达多巴胺 D1 或 D2 受体（D1-MSN、D2-MSN）和小胶质细胞的纹状体中棘神经元中 CB2R 的表达。我们发现单次注射可卡因未能改变，而重复注射可卡因或自我给药剂量依赖性上调新皮质、纹状体和外周（脾脏）中的 CB2R 基因表达。相反，重复服用海洛因会导致纹状体 CB2 mRNA 表达剂量依赖性降低。我们发现CB2R上调主要发生在D1-MSNs中，而不是在D2-MSNs或小胶质细胞中，在伏核而不是背侧纹状体中。这些发现表明，反复接触可卡因可能会上调大脑和脾脏中的 CB2R 表达，并具有区域和细胞类型特异性特征。在纹状体中，CB2R 上调主要发生在伏隔核的 D1-MSN 中。鉴于 D1-MSN 在大脑奖赏功能中的重要作用，这些发现为大脑 CB2R 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提示诱导的药物寻求恢复中发挥重要作用。但谷氨酸在药物奖励本身中的作用尚不清楚。因此，我们研究了多种谷氨酸转运蛋白（GLT）抑制剂对伏隔核（NAc）中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）以及雄性和雌性大鼠恢复可卡因寻求。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 中，但不注射到腹侧被盖区 (VTA) 或背侧纹状体 (DS) 中，在固定比例和渐进比例 (PR) 强化下剂量依赖性地抑制可卡因自我给药，改变了可卡因剂量反应曲线向下，并抑制颅内 BSR。 GLT-1反义寡核苷酸选择性下调NAc中星形胶质细胞GLT-1的表达也抑制了可卡因的自我给药。 TFB-TBOA 给药后可卡因自我给药的减少是 NMDA GluN2B 受体依赖性的，大鼠自我给药可卡因显示 NAc DA 和 cAMP 调节的磷蛋白 32 (DARPP-32) 阳性中棘神经元中 GluN2B 表达上调（MSN）。相比之下，当局部给予 NAc、VTA 或腹侧苍白球 (VP) 时，TFB-TBOA 会剂量依赖性地恢复可卡因寻求行为。 Intra-NAc TFB-TBOA 诱发的药物寻求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励作用具有负向调节作用，而多个大脑区域中过量的谷氨酸会触发寻求药物行为的恢复。我们还探讨了生长素释放肽在可卡因成瘾中的作用。我们发现：（1）可卡因升高生长素释放肽在维持可卡因自我给药和由可卡因条件刺激引起的可卡因寻求方面发挥着关键作用； (2)可卡因服用行为的获得与可卡因条件刺激对胃饥饿素分泌的可卡因刺激作用的获得有关，并且与VTA胃饥饿素受体mRNA水平的上调有关； (3) 用 JMV2959（一种选择性生长素释放肽受体拮抗剂）预处理来阻断生长素释放肽信号传导，可剂量依赖性地抑制具有可卡因自我给药史的行为消失的动物中由可卡因或育亨宾触发的可卡因寻求的恢复； (4) JMV2959预处理还抑制DAT-Cre小鼠中通过光遗传学刺激VTA多巴胺神经元维持的BSR和可卡因增强的BSR； (5)阿替洛尔对外周肾上腺素能1受体的阻断有效减弱可卡因引起的循环生长素释放肽的升高，并抑制可卡因自我给药和由可卡因引发的可卡因恢复。然而，胃饥饿素系统对阿片类药物诱发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研究。我们研究了大鼠内源性生长素释放肽系统与羟考酮自我给药行为之间的相互作用，以及生长素释放肽系统在小鼠中脑奖励回路光遗传学刺激驱动的 BSR 中的作用。羟考酮自我给药可显着升高血浆生长素释放肽、去酰基生长素释放肽和生长激素，但对血浆 LEAP2（一种新鉴定的内源性生长素释放肽受体 (GHS-R1a) 拮抗剂）没有影响。羟考酮自我给药导致血浆胃抑制多肽和胰岛素显着降低。自我给药羟考酮显着上调 VTA DA 神经元中的 GHS-R1a mRNA 水平。预处理选择性 GHS-R1a 拮抗剂 JMV29959 剂量依赖性地减少羟考酮自我给药，并降低渐进比例强化下羟考酮的断点。 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 野生型中显示出类似的作用，但在 GHS-R 敲除大鼠中则没有。 JMV2959 预处理显着抑制由选择性刺激 VTA DA 神经元驱动的 BSR，但不通过刺激小鼠中投射到 VTA 的纹状体 GABA 神经元驱动。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传导升高是羟考酮激发羟考酮吸毒的因果过程，并且针对胃饥饿素系统可能是除可卡因使用障碍之外的阿片类药物使用障碍的可行治疗方法。为了进一步推进我们的大麻素工作，我们探索了 PIMSR（一种缺乏反向激动剂特征的中性 CB1R 拮抗剂）对抗可卡因行为影响的治疗潜力。我们发现，全身给予 PIMSR 剂量依赖性地抑制固定比例 5 (FR5) 下的可卡因自我给药，但不是 FR1，强化，使可卡因自我给药剂量反应曲线向下移动，降低了渐进性下寻求可卡因的激励动机。 -比率强化，并减少线索诱导的可卡因寻求恢复。 PIMSR 还抑制口服蔗糖的自我给药。重要的是，根据场所调节的评估，单独使用 PIMSR 既不会带来奖励，也不会带来厌恶。然后我们使用 BSR 来探索中边缘 DA 系统在 PIMSR 活动中的可能参与。我们发现，PIMSR 剂量依赖性地减弱可卡因增强的电 BSR，但其本身无法改变电 BSR，而剂量依赖性地抑制转基因 DAT-Cre 小鼠中脑 DA 神经元的光刺激维持的 BSR，这表明 DA-依赖机制。我们还发现 PIMSR 预处理减弱了 THC 或 ACEA（选择性 CB1R 激动剂）引起的光学 BSR 降低。中性 CB1R 拮抗剂 PIMSR 作为可卡因使用障碍的一种有前途的药物治疗方法值得进一步研究。最后，我们发现长期体育锻炼会导致红核 c-fos 表达大幅增加，并激活投射到 VTA DA 神经元的内侧红核 (RNm) 谷氨酸神经元的子集。根据 BSR 和条件位置偏好的评估，该通路的光遗传学刺激是有益的。跑步轮的使用减少了可卡因的自我施用和可卡因的寻求。 RNm-to-VTA 谷氨酸途径的光遗传学刺激抑制了对可卡因的反应。这些发现表明，体育锻炼会激活特定的 RNm-VTA 谷氨酸通路，产生运动奖励并降低可卡因的吸引力。