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，目前还没有有效的治疗方法。 FDA批准的药物治疗。因此，显然需要鉴定新的神经细胞。 可卡因渴望和复吸的潜在机制，以开发新的药物疗法来治疗这一问题。 疾病我们最近发现，中枢胰高血糖素样肽-1受体（GLP-1 Rs）在调节胰岛素抵抗中起重要作用。 在可卡因强化和可卡因寻求的恢复中的作用，复发的动物模型。 具体来说，我们确定了选择性减少可卡因的GLP-1 R激动剂的行为相关剂量 寻求并没有产生与这些药物在人类中通常相关的不良反应， 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， 靶向预防可卡因渴求诱导的复发，介导GLP-1 R作用的神经机制 兴奋剂对可卡因寻求的影响尚不清楚。这项建议的一个目标是填补我们对以下问题的理解的空白： 调节可卡因寻求的中枢GLP-1回路在目标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，这两个核团已知在恢复中起关键作用 寻找可卡因我们还将使用系统神经科学方法对GLP-1 R表达细胞进行表型分析 并确定目标这些研究的结果将提供第一个全面的神经解剖学 大鼠大脑中GLP-1回路图。我们的初步研究还表明，GLP-1 Rs在星形胶质细胞上表达， 和神经元。使用Aim 2中的病毒介导的基因传递和纤维光度法，我们 将确定星形胶质细胞和/或神经元上选择性降低GLP-1 R表达是否阻止了 GLP-1 R激动剂对可卡因寻求的抑制作用。此外，我们将研究细胞类型特异性 可卡因复吸期间GLP-1 R活化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，可卡因自我管理和随后的禁欲动态 调节内源性前胰高血糖素原（PPG）（编码GLP-1的基因）在后脑中的表达。 这些令人激动的发现表明，在禁欲期间内源性PPG表达的减少可能有助于 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Aim 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）与后脑中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 内源性中枢GLP-1信号传导并强调可作为新型靶点的分子底物 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.