The role of central GLP-1 receptors in animal models of cocaine addiction

项目摘要 可卡因成瘾仍然是一个重大的公共卫生问题，目前还没有有效的解决办法 FDA批准的药物治疗。因此，显然有必要确定新的神经。 为了开发新的药物疗法来治疗可卡因渴求和复发的潜在机制 疾病。我们最近发现，中枢高血糖素样多肽-1受体(GLP-1RS)在 在加强可卡因和恢复寻求可卡因方面的作用，这是一种复发的动物模型。 具体地说，我们确定了行为相关剂量的GLP-1R激动剂，该激动剂选择性地减少可卡因 寻求并没有产生通常与这些药物有关的不良反应在人类和 啮齿动物。虽然这些令人兴奋的发现清楚地强调了一种新的神经内分泌机制，可能是 GLP-1R作用的神经机制旨在预防可卡因渴求引起的复发 寻找可卡因的激动剂仍不清楚。这项建议的目标之一是填补我们对 中枢GLP-1回路调节可卡因寻找。在目标1中，我们将扩展此电路以包括 外侧背侧被盖区(LDTg)和杏仁核，这两个已知在恢复过程中发挥关键作用的核团 寻找可卡因。我们还将使用系统神经科学的方法来研究表达GLP-1R的细胞的表型 并确定他们的目标。这些研究的发现将提供第一个全面的神经解剖学 大鼠大脑中GLP-1的电路图谱。我们的初步研究还显示，GLP-1Rs在星形胶质细胞上表达 以及大鼠大脑中的神经元。在Aim 2中使用病毒介导的基因传递和纤维光度法，我们 将确定在星形胶质细胞和/或神经元上选择性降低的GLP-1R表达是否可以阻止 GLP-1R激动剂对可卡因寻找的抑制作用。此外，我们还将研究特定的细胞类型 可卡因戒断过程中GLP-1R激活对星形胶质细胞活性和神经元功能的影响 寻找。我们还发现，可卡因的自我管理和随后的戒断是动态的 调节内源性前高血糖素原(PPG)在后脑中的表达，PPG是编码GLP-1的基因。 这些具有挑衅性的发现表明，在禁欲过程中内源性PPG表达减少可能有助于 寻找可卡因。然而，可卡因暴露调节的分子和表观遗传机制 PPG表达未知。我们将在目标3中使用染色质免疫沉淀(CHIP)方法来鉴定 组蛋白翻译后修饰(PTM)与后脑PPG转录减少相关。 我们还将确定调节可卡因诱导的PPG mRNA表达变化的转录因子。 总之，这些研究将为可卡因暴露如何影响提供新的机械性见解。 内源性中枢GLP-1信号转导和突显可作为新靶点的分子底物 治疗可卡因成瘾的药物。

Project Summary Cocaine addiction continues to be a significant public health problem for which there are currently no effective FDA-approved pharmacological treatments. Therefore, there is a clear need to identify novel neural mechanisms underlying cocaine craving and relapse in order to develop new pharmacotherapies to treat this disease. We have recently shown that central glucagon-like peptide-1 receptors (GLP-1Rs) play an important role in cocaine reinforcement and the reinstatement of cocaine seeking, an animal model of relapse. Specifically, we identified behaviorally relevant doses of a GLP-1R agonist that selectively reduced cocaine seeking and did not produce adverse effects commonly associated with these medications in humans and rodents. While these exciting findings clearly highlight a novel neuroendocrine mechanism that could be targeted to prevent cocaine craving-induced relapse, the neural mechanisms mediating the effects of GLP-1R agonists on cocaine seeking remain unclear. One goal of this proposal is to fill the gaps in our understanding of the central GLP-1 circuits regulating cocaine seeking. In Aim 1, we will extend this circuitry to include the lateral dorsal tegmental area (LDTg) and amygdala, two nuclei known to play critical roles in the reinstatement of cocaine seeking. We will also use a systems neuroscience approach to phenotype GLP-1R-expressing cells and identify their targets. Findings from these studies will provide the first comprehensive neuroanatomical map of GLP-1 circuits in the rat brain. Our pilot studies also reveal that GLP-1Rs are expressed on astrocytes and neurons in the rat brain. Using viral-mediated gene delivery and fiber photometry approaches in Aim 2, we will determine if reduced GLP-1R expression selectively on astrocytes and/or neurons prevents the suppressive effects of a GLP-1R agonist on cocaine seeking. In addition, we will investigate cell-type specific effects of GLP-1R activation on astrocyte activity and neuronal function during the reinstatement of cocaine seeking. We have also discovered that cocaine self-administration and subsequent abstinence dynamically regulate expression of endogenous preproglucagon (PPG), the gene that encodes GLP-1, in the hindbrain. These provocative findings suggest that reduced endogenous PPG expression during abstinence may facilitate cocaine seeking. However, the molecular and epigenetic mechanisms by which cocaine exposure regulates PPG expression are unknown. We will use chromatin immunoprecipitation (ChIP) methods in Aim 3 to identify the histone posttranslational modifications (PTMs) associated with reduced PPG transcription in the hindbrain. We will also identify transcription factors that regulate cocaine-induced changes in PPG mRNA expression. Together, these studies will provide new mechanistic insights into how cocaine exposure influences endogenous central GLP-1 signaling and highlight molecular substrates that could serve as targets for novel medications to treat cocaine addiction.