VTA Glutamate and Orexin Involvement in Cue Reinstatement of Drug Seeking

描述（由申请人提供）：该提案探讨了巴甫洛夫线索驱动的可卡因寻求恢复中食欲素和谷氨酸传入腹侧被盖区（VTA）的作用。在这种药物复发的动物模型中，大鼠被训练通过按下杠杆来自我施用可卡因加上条件刺激（CS），然后在这种行为上被熄灭。在后来的测试中，按下杠杆会得到可卡因相关的CS奖励，但没有可卡因。大多数动物强烈恢复熄灭的药物寻求行为，这被认为是在恢复暴露于巴甫洛夫药物线索的人类成瘾者中复发的模型。 腹侧被盖区向前脑的多巴胺投射对于药物相关线索促进药物寻求是至关重要的，然而控制线索相关的腹侧被盖区放电的输入却知之甚少。Orexin和谷氨酸都促进VTA的药物觅药和多巴胺细胞放电，内侧前额叶皮层（mPFC）对VTA的投射具有协同作用，是CS恢复药物觅药所必需的。此外，食欲素促进兴奋腹侧被盖区多巴胺神经元的谷氨酸输入mPFC。在这里，我们建议采用解剖学，免疫组织化学，药理学和行为学技术相结合，检查三个相关的问题。1)mPFC或其他VTA谷氨酸传入Fos是否被可卡因CS激活，这种激活是否与线索触发的可卡因寻求有关？2)谷氨酸、食欲素或两者在腹侧被盖区的共同激活是否是可卡因相关线索触发可卡因寻求恢复所必需的？3)同时激活mPFC谷氨酸和食欲素对VTA的输入是CS恢复所必需的吗？为了解决这些问题，我们使用Fos和道跟踪技术，微量注射食欲素和谷氨酸拮抗剂在腹侧被盖区，和同时失活的mPFC和对侧拮抗腹侧被盖区食欲素受体。 许多人想戒烟，但当他们试图戒烟时，却一再复发。一个风险因素是暴露于以前与药物相关的环境线索，因此了解大脑如何处理这些线索对于开发预防复发的疗法至关重要。在这里，我们使用多学科的神经科学技术来研究线索触发的药物寻求恢复的神经回路，进一步加深我们对成瘾的大脑基质的理解。

DESCRIPTION (provided by applicant): This proposal explores the role of orexin and glutamate afferents to the ventral tegmental area (VTA) in Pavlovian cue-driven reinstatement of cocaine seeking. In this animal model of drug relapse, rats are trained to self-administer cocaine plus a conditioned stimulus (CS) by pressing a lever, then are extinguished on this behavior. On later test days, lever presses are rewarded with the cocaine-associated CS, but no cocaine. Most animals robustly reinstate extinguished drug seeking behavior, which is thought to model relapse in recovering human addicts exposed to Pavlovian drug cues. VTA dopamine projections to forebrain are crucial for drug-associated cues to promote drug seeking, yet the inputs controlling cue-related VTA firing are poorly understood. Orexin and glutamate both promote drug seeking and dopamine cell firing in VTA, and medial prefrontal cortex (mPFC) projects glutamatergically to VTA and is necessary for CS reinstatement of drug seeking. Moreover, orexin facilitates excitation of VTA dopamine neurons by glutamate inputs from mPFC. Here, we propose employing a combination of anatomical, immunohistochemical, pharmacological, and behavioral techniques to examine three related questions. 1) Are mPFC or other VTA glutamate afferents Fos activated by cocaine CSs, and is this activation related to cue-triggered cocaine seeking? 2) Are glutamate, orexin, or co-activation of the two in VTA necessary for cocaine-associated cues to trigger reinstatement of cocaine seeking? 3) Is simultaneous activation of mPFC glutamate and orexin inputs to VTA necessary for CS reinstatement? To address these questions, we use Fos and tract tracing techniques, microinjections of orexin and glutamate antagonists in VTA, and simultaneous inactivation of mPFC and contralateral antagonism of VTA orexin receptors. Many people want to quit using drugs, yet repeatedly relapse when they try to quit. One risk factor is exposure to environmental cues previously associated with drugs, so understanding how the brain processes these cues is crucial for development of therapies to prevent relapse. Here we use multidisciplinary neuroscience techniques to examine the neural circuitry of cue-triggered reinstatement of drug seeking, furthering our understanding of the brain substrates of addiction.