Synaptic mechanims underlying reward seeking and comupulsive drug use

奖励寻求和强迫性药物使用的突触机制

• 批准号: 8559269
• 负责人: Veronica A Alvarez
• 金额: $ 96.09万
• 依托单位: NATIONAL INSTITUTE ON ALCOHOL ABUSE AND ALCOHOLISM
• 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/8559269
• 关键词: AMPA Receptors; Acute; Addictive Behavior; Address; Affect; Agonist; Agreement; Alcohol consumption; Alcohols; Amphetamines; Animals; Area; Bathing; Behavior; Behavioral; Biochemistry; Blood; Brain; Brain region; Cells; Chemosensitization; Chronic; Circadian Rhythms; Cocaine; Cocaine Users; Consumption; Corpus striatum structure; DRD2 gene; Data; Dependence; Depressed mood; Development; Disease; Dissection; Dopamine D2 Receptor; Drug usage; Electric Stimulation; Electrophysiology (science); Ethanol; Globus Pallidus; Glutamates; Hour; Individual; Inhibitory Concentration 50; Intake; Interneurons; Intoxication; Investigation; Laboratories; Laser Scanning Microscopy; Lasers; Length; Mediating; Mental Depression; Midbrain structure; Modeling; Morphology; Motivation; Mouse Strains; Mus; N-Methylaspartate; Neurobiology; Neurons; Nucleus Accumbens; Obsessive compulsive behavior; Output; Pathway interactions; Patients; Pattern; Persons; Pharmaceutical Preparations; Photons; Physiologic pulse; Play; Predisposition; Prefrontal Cortex; Preparation; Property; Psychiatry; Recruitment Activity; Research; Resolution; Rewards; Role; Scanning; Self Administration; Self-control as a personality trait; Signal Transduction; Speed; Structure; Sucrose; Sulpiride; Synapses; Techniques; Testing; Therapeutic Uses; Time; Vertebral column; Wild Type Mouse; addiction; carbon fiber; cholinergic; cocaine exposure; cocaine use; density; dopaminergic neuron; drinking; drinking behavior; drug of abuse; extracellular; fighting; gamma-Aminobutyric Acid; motor impairment; mouse model; novel; postsynaptic; preference; presynaptic; research study; response; success; tool; transmission process; AMPA Receptors; Acute; Addictive Behavior; Address; Affect; Agonist; Agreement; Alcohol consumption; Alcohols; Amphetamines; Animals; Area; Bathing; Behavior; Behavioral; Biochemistry; Blood; Brain; Brain region; Cells; Chemosensitization; Chronic; Circadian Rhythms; Cocaine; Cocaine Users; Consumption; Corpus striatum structure; DRD2 gene; Data; Dependence; Depressed mood; Development; Disease; Dissection; Dopamine D2 Receptor; Drug usage; Electric Stimulation; Electrophysiology (science); Ethanol; Globus Pallidus; Glutamates; Hour; Individual; Inhibitory Concentration 50; Intake; Interneurons; Intoxication; Investigation; Laboratories; Laser Scanning Microscopy; Lasers; Length; Mediating; Mental Depression; Midbrain structure; Modeling; Morphology; Motivation; Mouse Strains; Mus; N-Methylaspartate; Neurobiology; Neurons; Nucleus Accumbens; Obsessive compulsive behavior; Output; Pathway interactions; Patients; Pattern; Persons; Pharmaceutical Preparations; Photons; Physiologic pulse; Play; Predisposition; Prefrontal Cortex; Preparation; Property; Psychiatry; Recruitment Activity; Research; Resolution; Rewards; Role; Scanning; Self Administration; Self-control as a personality trait; Signal Transduction; Speed; Structure; Sucrose; Sulpiride; Synapses; Techniques; Testing; Therapeutic Uses; Time; Vertebral column; Wild Type Mouse; addiction; carbon fiber; cholinergic; cocaine exposure; cocaine use; density; dopaminergic neuron; drinking; drinking behavior; drug of abuse; extracellular; fighting; gamma-Aminobutyric Acid; motor impairment; mouse model; novel; postsynaptic; preference; presynaptic; research study; response; success; tool; transmission process

Project 1: Synaptic potentiation in D2 receptor expressing neurons in the accumbens confers protection against the development of compulsive cocaine use. (Bock, Shin et al.; under revision) The hypothesis behind this study is that the vulnerability to develop compulsive cocaine use arises in part from inherent differences across animals in the ability to recruit the D2-MSNs and engage the indirect accumbal-tegmental pathway. Evidence from previous studies suggests that activation of D2 receptors is involved in the locomotor response to cocaine and conditioned place preference (Durieux et al., 2009; Ferguson et al., 2011). However, it is still unclear what the role of D2-MSNs is with regard to voluntary cocaine self-administration and the development of compulsive cocaine use. Experiments also test the hypothesis that inhibition of D2-MSNs impairs self-control over cocaine intake and renders individuals more susceptible to the rewarding effects of the drug. The results showed that potentiation of excitatory inputs onto D2-MSNs occurs only in mice that can exert self-control over cocaine intake, and suggest that the potentiation might confer protection. Furthermore, the experiments suggested that inhibition of D2-MSN output renders mice vulnerable to the expression of compulsive behaviors by enhancing the motivation to obtain cocaine, without affecting drug use when it is readily available. These data are in agreement with previous studies showing that reinstatement of cocaine seeking is associated with reduced extracellular GABA in the ventral pallidum (Tang et al., 2005). In conclusion, this study establishes synaptic potentiation in D2-MSN inputs as a critical mechanism for controlling the expression of compulsive behaviors towards cocaine. We propose that this cell-specific synaptic potentiation facilitates the recruitment of indirect pathway neurons and protects against the development addictive behaviors. This study also showed that manipulations of D2-MSN activity, even when introduced after several weeks of drug taking, can successfully alter the motivation to obtain cocaine. The use of therapeutic brain stimulation to silence ventral pallidum neurons or to selectively activate D2-MSNs could enhance self-control in patients fighting dependence on drugs of abuse. Project 2: Acute cocaine effects on glutamatergic and dopaminergic transmission in the nucleus accumbens (Adrover, Shin and Alvarez, in preparation) Glutamatergic inputs to the NAc that originate in the VTA have been recently demonstrated and recent studies suggest that glutamatergic transmission from VTA DA neurons plays an important role in the rewarding properties of cocaine and amphetamine (Birgner et al., 2010; Kozorovitskiy et al., 2012), as well as enhanced sucrose and cocaine self-administration (Alsio et al., 2011). However, the properties of these synapses are poorly understood and the effect of cocaine unknown. In this study, optogenic tools are used to selectively activate terminals from VTA DA neurons into the NAc and investigate the acute effect of cocaine on DA and glutamatergic transmission. ChR2 activation in the NAc shell region was achieved by a brief laser pulse and triggered DA transients that were recorded with a carbon fiber using fast scanning cyclic voltammetry (FSCV). DA transients evoked by ChR2 activation also had similar properties to those evoked by electrical stimulation. This same ChR2 activation evoked glutamatergic excitatory postsynaptic currents (EPSCs) in MSNs of the shell that were abolished by TTX but were insensitive to D1R and D2R antagonists. The average amplitude of the AMPA receptor-mediated EPSC was 101 9 pA and the average AMPA/NMDA ratio was 1.5 0.2. Bath-application of cocaine (10 M) prolonged the DA transients and increasing the decay time constant by a factor of 10 (3.5 0.6 s). The area of the DA transient was increased 2.5 times and the peak was transiently enhanced. In contrast, cocaine inhibited AMPA-R mediated EPSCamplitude by half. A similar pattern of depression was observed in the NMDA-R mediated EPSCs.The D2R antagonist sulpiride reversed the inhibition of both AMPA-R and NMDA-R mediated EPSCs when applied after cocaine. These data indicated that D2R activation is required for cocaine-induced inhibition of EPSCs and indeed, a D2-like agonist inhibited the DA transients and also glutamatergic EPSCs in a concentration dependent manner and with a similar IC50, indicating that VTA terminals that release glutamate also express presynaptic D2Rs. D2R are expressed by indirect pathway MSNs, cholinergic interneurons and also on presynaptic DA terminals where they inhibit DA release. Mice lacking D2R only in DA neurons were also tested. Cocaine increased DA transients by 50% and had no effect on AMPA-R EPSCs in these mice. Furthermore, the DA transient response to cocaine was similar to those of wild-type mice when cocaine was added in the presence of sulpiride. These results indicate that acute cocaine, in addition to causing larger DA transients, acts on presynaptic D2R to inhibit DA and glutamate release from VTA terminals. Furthermore, these results suggest that cocaine, acting via these mechanisms, has opposite effects on DA and glutamatergic transmission from midbrain DA neurons, enhancing the first and depressing the latter. Project 3: Dissection of the drinking behavior and analysis of spine morphology in a mouse model of binge-like ethanol drinking (Wilcox et al., under review) Research into the neurobiology of heavy and binge-like ethanol drinking has been limited by the low-levels of voluntary ethanol consumption shown by most mouse strains (Crabbe et al., 2011). Recently, a model of intermittent access to ethanol has been shown to elicit binge-like drinking and pharmacologically relevant blood ethanol concentrations (BECs) in mice (Rhodes et al., 2005). Termed Drinking in the Dark, this model takes advantage of the circadian patterns of mice to achieve reliably high levels of consumption in a two hour drinking session. C57BL/6J mice reach BECs higher than 80 mg/dl, and show signs of intoxication such as motor impairment (Rhodes et al., 2007). DID is a robust paradigm that has been successfully used to investigate neuronal circuits and signals that modulate binge-like ethanol consumption (Sprow, 2012). Despite the success of this intermittent access model, the mechanisms underlying the acquisition of voluntary ethanol drinking are not completely understood. In this study, we established DID in our laboratory and showed that it produces reliable escalation of voluntary ethanol intake and blood ethanol concentration. We characterized the drinking pattern of mice with intermittent access to ethanol using lickometers to record each bout with high temporal resolution over many weeks of voluntary ethanol consumption, and analyzed the synaptic morphology of striatal neurons 2 days and 30 days after the last ethanol binge. The results represent a novel and important contribution to the alcohol field because they identify the bottle exchange, an integral part of DID, as a likely mechanism by which intermittent access facilitates the acquisition of voluntary ethanol drinking behavior by inducing mice to drink at a higher rate. Over time, mice change their ethanol drinking pattern and increase the speed of drinking at the beginning of each DID session. Faster ethanol drinking is associated with higher BEC, and an enhanced preference for ethanol was observed after 6 weeks of treatment. Interestingly, no changes were detected in either striatal or accumbal spine density, and a shortening of spine length was seen only transiently, suggesting that these behavioral changes occur independent of long-term changes in synaptic morphology in brain regions involved in the reward pathway.

项目1：D2受体中表达神经元的突触增强，赋予了防止强迫性可卡因使用的保护。 （Bock，Shin等人；在修订中） 这项研究背后的假设是，发展强迫性可卡因使用的脆弱性部分是由于动物之间的固有差异在募集D2-MSN并参与间接的副不见的副均方途径的能力中产生。先前研究的证据表明，D2受体的激活参与对可卡因的运动反应和条件的位置偏好（Durieux等，2009； Ferguson等，2011）。但是，目前尚不清楚D2-MSN的作用在自愿性可卡因自我管理和强迫性可卡因使用的发展方面是什么作用。实验还检验了以下假设：抑制D2-MSN会损害对可卡因摄入量的自我控制，并使个人更容易受到该药物的奖励作用。 结果表明，在D2-MSN上的兴奋性输入的增强仅发生在可以在可卡因摄入量上施加自我控制的小鼠中，并表明该增强性可能提供保护。此外，实验表明，抑制D2-MSN输出的抑制使小鼠通过增强获得可卡因的动机而容易表达强迫行为，而无需在易于获得药物时影响药物的使用。这些数据与先前的研究一致，表明恢复可卡因的寻求与腹侧粒细胞外GABA的降低有关（Tang等，2005）。 总之，这项研究在D2-MSN输入中建立了突触增强，作为控制可卡因强迫行为表达的关键机制。 我们建议这种细胞特异性的突触增强有助于募集间接途径神经元，并防止发展成瘾行为。这项研究还表明，即使在服用数周后引入了D2-MSN活性的操纵也可以成功改变获得可卡因的动机。使用治疗性脑刺激来沉默腹侧钯神经元或选择性激活D2-MSN可以增强对抗依赖滥用药物的患者的自我控制。 项目2：急性可卡因对伏隔核中谷氨酸能和多巴胺能传播的影响（Adrover，Shin和Alvarez，准备准备） 最近已经证明了起源于VTA的NAC的谷氨酸能力输入，并且最近的研究表明，VTA DA神经元的谷氨酸能传播在可卡因和苯丙胺的奖励性能中起着重要作用（Birgner等，2010； Kozorovitskiy等人，以及Als and Sucer（Al），以及自行的Suse（以及增强的Sus）。 Al。，2011）。但是，这些突触的特性知之甚少，可卡因的影响未知。 在这项研究中，光源工具用于选择性地激活从VTA DA神经元进入NAC的末端，并研究可卡因对DA和谷氨酸能传播的急性效应。通过短暂的激光脉冲实现了NAC壳区域中的CHR2激活，并触发了使用快速扫描环状伏安法（FSCV）记录的DA瞬变。 CHR2激活引起的DA瞬变也具有与电刺激引起的瞬态特性相似的特性。在壳的MSN中，同样的CHR2激活引起了谷氨酸能激发的突触后电流（EPSC），被TTX废除，但对D1R和D2R拮抗剂不敏感。 AMPA受体介导的EPSC的平均幅度为101 9 PA，平均AMPA/NMDA比为1.5 0.2。 可卡因（10 m）的浴涂层延长了DA瞬变，并将衰减时间常数增加10倍（3.5 0.6 s）。 DA瞬态的面积增加了2.5倍，峰值瞬时增强。相比之下，可卡因抑制AMPA-R介导的ePspamplituditude。在NMDA-R介导的EPSC中也观察到了类似的抑郁模式。D2R拮抗剂硫酸盐逆转可卡因后应用AMPA-R和NMDA-R介导的EPSC的抑制作用。这些数据表明，D2R激活是可卡因诱导的EPSC抑制作用所必需的，实际上，D2样激动剂以浓度依赖于浓度的IC50抑制DA瞬变和谷氨酸能EPSC，并以类似的IC50抑制了DA瞬态EPSC，这表明释放谷氨酸的VTA末端也表达了谷氨酸末端也表达了谷氨酸释放的PresyNaptic D22Rs。 D2R通过间接途径MSN，胆碱能中间神经元以及突触前DA末端抑制DA释放来表达。还测试了仅在DA神经元中缺乏D2R的小鼠。可卡因将DA瞬变增加了50％，对这些小鼠的AMPA-R EPSC没有影响。此外，在硫酸盐存在下加入可卡因时，对可卡因的DA瞬时反应与野生型小鼠相似。这些结果表明，急性可卡因除了引起较大的DA瞬变外，还作用于突触前的D2R，可抑制DA和谷氨酸从VTA末端释放。此外，这些结果表明，可卡因通过这些机制作用，对中脑DA神经元的DA和谷氨酸能传播具有相反的影响，从而增强了第一个并抑制后者。 项目3：在暴饮暴食的小鼠模型中对饮酒行为和脊柱形态分析的解剖（Wilcox等，正在综述） 大多数小鼠菌株表现出的低水平自愿性乙醇消耗的限制了对重和暴饮暴食的神经生物学的研究（Crabbe等，2011）。最近，已经显示出一种间歇性进入乙醇的模型引起小鼠的暴饮暴食和与药理学相关的血液乙醇浓度（BEC）（Rhodes等，2005）。该模型被称为黑暗中的饮酒，利用小鼠的昼夜节律模式在两个小时的饮酒中可靠地消费。 C57BL/6J小鼠的BEC达到高于80 mg/dl的BEC，并显示出诸如运动障碍之类的中毒迹象（Rhodes等，2007）。 DID是一个强大的范式，已成功地用于研究调节暴饮暴食样乙醇消耗的神经元电路和信号（Sprow，2012）。尽管这种间歇性访问模型取得了成功，但尚未完全了解获得自愿乙醇饮用的机制。在这项研究中，我们在实验室中建立了DIC，并表明它会产生自愿乙醇摄入和血液乙醇浓度的可靠升级。我们表征了小鼠的饮用模式，并使用舔仪间歇性地进入乙醇，以在数周的自愿性乙醇消耗中记录每个回合，并以高时间分辨率记录乙醇，并分析了最后一次乙醇狂饮后2天和30天分析了纹状体神经元的突触形态。结果代表了对酒精场的新颖而重要的贡献，因为它们确定了瓶装交换，这是DID的组成部分，这是一种可能的机制，通过这种机制，间歇性通道通过诱导小鼠以较高的速度饮酒来促进获得自愿性乙醇饮酒行为。 随着时间的流逝，老鼠会改变其乙醇饮用方式，并在每次会议开始时提高饮酒速度。 更快的乙醇饮用与较高的BEC相关，并且在治疗6周后观察到了对乙醇的偏爱。有趣的是，在纹状体或伏脊柱密度中均未检测到任何变化，并且仅暂时看到脊柱长度的缩短，这表明这些行为变化发生在奖励途径中涉及的大脑区域突触形态的长期变化。