Synaptic mechanisms underlying reward seeking and compulsive drug use

项目A：前额叶皮层驱动的纹状体多巴胺信号显示出独特的空间和药理学特性。纹状体中的多巴胺信号对各种重要过程至关重要，包括动机，运动学习和强化学习。纹状体多巴胺信号可以通过直接激活来自中脑多巴胺神经元（DAN）的输入以及皮层和丘脑到纹状体的输入来诱发。在这项研究中，我们表明，在体内光遗传学刺激前边缘（PrL）和边缘下（IL）皮层传入纹状体触发细胞外多巴胺浓度的增加，这与纹状体乙酰胆碱（ACh）水平的升高相一致。这种增加被烟碱乙酰胆碱受体（nAChR）拮抗剂阻断。使用单或双光遗传学刺激的大脑切片从男性和女性小鼠，我们比较了这些催乳素/IL诱发的多巴胺信号的性质与中脑DAN轴突投射的刺激所诱发的。PrL/IL诱发的多巴胺信号与DAN诱发的多巴胺信号在它们的幅度和电化学性质上是不可区分的。然而，PrL/IL诱发的多巴胺信号在空间上受到限制，并优先记录在背内侧纹状体。PrL/IL诱发的多巴胺信号在其药理学性质上也不同，需要激活谷氨酸和烟碱ACh受体。因此，在体内和体外的结果表明，皮质诱发的多巴胺信号依赖于招募胆碱能中间神经元，这使得多巴胺信号不太能够在列车的刺激和更敏感的胆碱能药物和温度期间汇总。总之，皮质和中脑输入纹状体引起多巴胺信号具有独特的空间和药理学特性，可能塑造他们的功能角色和行为相关性。 项目B：惩罚性乙醇自我给药的前额调节：酒精使用障碍的临床特征是持续饮酒，尽管有潜在的不良后果。腹内侧前额叶皮层（vmPFC）和背内侧前额叶皮层（dmPFC）的位置施加自上而下的控制皮质下区域，如核壳（NAcS）和基底外侧杏仁核，编码积极和消极的价格乙醇（EtOH）相关的刺激。先前的啮齿动物研究表明这些区域参与了惩罚性EtOH自我给药（EtOH-SA）的调节。我们在小鼠vmPFC和dmPFC中进行了体内电生理记录，以获得足电击惩罚EtOH-SA的神经元相关性。在接受vmPFC输入的表达NAcS D1受体的中等多刺神经元中进行离体记录，以检查该通路中与惩罚相关的可塑性。采用光遗传学光沉默来评估vmPFC、dmPFC、vmPFC向NAcS的投射或vmPFC向基底外侧杏仁核的投射对惩罚EtOH-SA的功能贡献。惩罚减少了EtOH杠杆按压，并导致按压中止（杠杆接近，然后快速缩回）。在vmPFC和dmPFC的神经元表现出阶段性发射乙醇杠杆按下和中止，但只有在vmPFC有一个人口水平的转变，从杠杆按下与惩罚中止编码。闭环vmPFC，但不是dmPFC，光沉默的postpunishment探针测试否定了减少乙醇杠杆压力，但不是在中止。惩罚与改变可塑性在vmPFC输入D1受体表达中型多刺神经元的NAcS。光沉默vmPFC预测NAcS，但不基底外侧杏仁核，部分逆转抑制乙醇杠杆按下探针测试。这些研究结果表明，vmPFC在惩罚后调节EtOH-SA的关键作用，对理解酒精使用障碍中强迫性饮酒的神经基础具有重要意义。 项目C：CD 38 rs3796863多态性在酒精和金钱奖励中的作用：来自CD 38敲除小鼠和酒精自我给药，11 C-雷氯必利结合和人类功能性MRI的证据分化簇38（CD 38）是在脑中的多巴胺能奖赏通路（包括丘脑核（NAc））中表达的跨膜蛋白。CD 38中常见单核苷酸多态性（SNP）rs3796863的GG基因型与社会奖励增加相关。我们研究了CD 38 rs3796863和Cd 38敲除（KO）是否与奖励相关的神经和行为表型相关。来自四项独立的人类研究的数据用于测试rs3796863基因型是否与以下相关：（1）静脉注射酒精自我管理（n = 64，30名女性），（2）使用11 C-雷氯必利正电子发射断层扫描测量酒精刺激的多巴胺（DA）释放（n = 22名男性），（3）腹侧纹状体（VS）对正反馈的反应，使用猜牌功能磁共振成像（fMRI）范例测量（n = 531，276名女性），和（4）VS的静息状态功能连接（rsfc）（n = 51，26名女性）。在第五项研究中，我们使用小鼠模型，以检查是否cd 38敲除影响刺激DA释放的NAc核心和背侧纹状体使用快速扫描循环伏安法。相对于T等位基因携带者，在CD 38内rs3796863的G纯合子的特征在于更大的酒精自我管理，酒精刺激的多巴胺释放，VS对正反馈的反应，以及VS和前扣带皮层之间的rsfc。在Cd 38 KO小鼠的NAc中，高频刺激DA释放减少。越来越多的证据表明，CD 38 rs3796863基因型可能会增加DA相关的奖励反应和酒精消费。

Project A: Prefrontal cortex driven dopamine signals in the striatum show unique spatial and pharmacological properties. Dopamine signals in the striatum are critical for a variety of vital processes, including motivation, motor learning and reinforcement learning. Striatal dopamine signals can be evoked by direct activation of inputs from midbrain dopamine neurons (DANs) as well as cortical and thalamic inputs to the striatum. In this study, we show that in vivo optogenetic stimulation of prelimbic (PrL) and infralimbic (IL) cortical afferents to the striatum triggers an increase in extracellular dopamine concentration, which coincides with elevation of striatal acetylcholine (ACh) levels. This increase is blocked by a nicotinic ACh receptor (nAChR) antagonist. Using single or dual optogenetic stimulation in brain slices from male and female mice, we compared the properties of these PrL/IL evoked dopamine signals with those evoked by stimulation from midbrain DAN axonal projections. PrL/IL evoked dopamine signals are indistinguishable from DAN evoked dopamine signals in their amplitudes and electrochemical properties. However, PrL/IL evoked dopamine signals are spatially restricted and preferentially recorded in the dorsomedial striatum. PrL/IL evoked dopamine signals also differ in their pharmacological properties, requiring activation of glutamate and nicotinic ACh receptors. Thus, both in vivo and in vitro results indicate that cortical evoked dopamine signals rely on recruitment of cholinergic interneurons, which renders dopamine signals less able to summate during trains of stimulation and more sensitive to both cholinergic drugs and temperature. In conclusion, cortical and midbrain inputs to the striatum evoke dopamine signals with unique spatial and pharmacological properties that likely shape their functional roles and behavioral relevance. Project B: Prefrontal Regulation of Punished Ethanol Self-administration.A clinical hallmark of alcohol use disorder is persistent drinking despite potential adverse consequences. The ventromedial prefrontal cortex (vmPFC) and dorsomedial prefrontal cortex (dmPFC) are positioned to exert top-down control over subcortical regions, such as the nucleus accumbens shell (NAcS) and basolateral amygdala, which encode positive and negative valence of ethanol (EtOH)-related stimuli. Prior rodent studies have implicated these regions in regulation of punished EtOH self-administration (EtOH-SA). We conducted in vivo electrophysiological recordings in mouse vmPFC and dmPFC to obtain neuronal correlates of footshock-punished EtOH-SA. Ex vivo recordings were performed in NAcS D1 receptor expressing medium spiny neurons receiving vmPFC input to examine punishment-related plasticity in this pathway. Optogenetic photosilencing was employed to assess the functional contribution of the vmPFC, dmPFC, vmPFC projections to NAcS, or vmPFC projections to basolateral amygdala, to punished EtOH-SA. Punishment reduced EtOH lever pressing and elicited aborted presses (lever approach followed by rapid retraction). Neurons in the vmPFC and dmPFC exhibited phasic firing to EtOH lever presses and aborts, but only in the vmPFC was there a population-level shift in coding from lever presses to aborts with punishment. Closed-loop vmPFC, but not dmPFC, photosilencing on a postpunishment probe test negated the reduction in EtOH lever presses but not in aborts. Punishment was associated with altered plasticity at vmPFC inputs to D1 receptor expressing medium spiny neurons in the NAcS. Photosilencing vmPFC projections to the NAcS, but not to the basolateral amygdala, partially reversed suppression of EtOH lever presses on probe testing. These findings demonstrate a key role for the vmPFC in regulating EtOH-SA after punishment, with implications for understanding the neural basis of compulsive drinking in alcohol use disorder. Project C: A role for the CD38 rs3796863 polymorphism in alcohol and monetary reward: evidence from CD38 knockout mice and alcohol self-administration, 11C-raclopride binding, and functional MRI in humans. Cluster of differentiation 38 (CD38) is a transmembrane protein expressed in dopaminergic reward pathways in the brain, including the nucleus accumbens (NAc). The GG genotype of a common single nucleotide polymorphism (SNP) within CD38, rs3796863, is associated with increased social reward. We examined whether CD38 rs3796863 and Cd38 knockout (KO) are associated with reward-related neural and behavioral phenotypes. Data from four independent human studies were used to test whether the rs3796863 genotype is associated with: (1) intravenous alcohol self-administration (n = 64, 30 females), (2) alcohol-stimulated dopamine (DA) release measured using 11C-raclopride positron emission tomography (n = 22 men), (3) ventral striatum (VS) response to positive feedback measured using a card guessing functional magnetic resonance imaging (fMRI) paradigm (n = 531, 276 females), and (4) resting state functional connectivity (rsfc) of the VS (n = 51, 26 females). In a fifth study, we used a mouse model to examine whether cd38 knockout influences stimulated DA release in the NAc core and dorsal striatum using fast-scanning cyclic voltammetry. Relative to T allele carriers, G homozygotes at rs3796863 within CD38 were characterized by greater alcohol self-administration, alcohol-stimulated dopamine release, VS response to positive feedback, and rsfc between the VS and anterior cingulate cortex. High-frequency stimulation DA release was reduced in Cd38 KO mice in the NAc. Converging evidence suggests that the CD38 rs3796863 genotype may increase DA-related reward response and alcohol consumption.