The Role of Microbiome Composition in Amphetamine Abuse

项目总结/摘要：苯丙胺类药物（AMPHs）是一种常用于治疗的精神兴奋剂 神经精神障碍（例如注意力缺陷障碍）。它们也被滥用，造成毁灭性的后果。 AMPHs的滥用可能性与其引起细胞质多巴胺动员的能力有关 (DA)，这导致细胞外DA水平的增加。这种增加是由DA的逆转介导的 转运蛋白（DAT）功能，其引起非囊泡性DA释放，此处定义为DA流出。值得注意的是， DA流出的抑制降低了AMPH增加运动活性和AMPH偏好的能力8 - 10。 肠道菌群的失衡（生态失调）被认为参与了腹泻的发病机制。 药物使用障碍11.此外，滥用精神兴奋剂会导致生命力失调12 - 15。因此能够 肠道微生物及其代谢物的变化可能不仅是药物使用的结果， 疾病，但可能在介导对滥用药物的行为反应中发挥作用11。 微生物产物，如短链脂肪酸（SCFAs），被认为在脂肪代谢中起着重要作用。 调节肠脑轴16。在SCFA中，已知丁酸盐可穿过BBB并直接作用于神经元 和神经胶质细胞17。具核梭杆菌（Fusobacterium nucleatum, F. nucleatum）是厌氧的、丝状的、革兰氏阴性细菌 分泌丁酸盐的物种，其生长受AMPH滥用的刺激13 - 15。 我们的数据表明，在无菌（知菌）果蝇中，F。核仁增强 AMPH诱导的DA流出（在离体蝇脑中记录）以及AMPH行为。这种增强作用 AMPH的作用由F. nucleatum与丁酸盐的口服给药平行。从机械的角度去理解， F.核仁促进AMPH作用，重要的是要考虑到DAT表达的变化调节 AMPH诱导的DA流出和精神运动性活动19。此外，丁酸盐是一种有效的组蛋白抑制剂 脱乙酰基酶（HDAC）20 - 22;抑制HDAC可显著增加DAT mRNA和 蛋白质21 - 23。 我们的假设是F. nucleatum通过提高DAT表达增强AMPH作用。这是介 通过分泌丁酸盐、HDAC抑制、和增强果蝇DAT（dDAT）启动子的乙酰化。我们将 通过以下具体目标来检验这一假设： S.A. #1.为了确定F.核仁调节dDAT的表达。 S.A. #2.为了测试，机械地，如何F。核仁增加AMPH诱导的DA外排。 S.A.的实验#1 - 2将在我们实验室开发的一个模型--果蝇脑中进行 以研究AMPH的体外作用。此外，使用成年果蝇，我们将能够翻译分子 S.A.的发现#1 - 2至特定的AMPH行为表型。因此，S.A.第三个重点是行为。 S.A. #3.为了定义F.核仁增强AMPH行为。

Project Summary/Abstract: Amphetamines (AMPHs) are psychostimulants commonly used for the treatment of neuropsychiatric disorders (e.g. attention deficit disorders). They are also abused, with devastating outcomes. The abuse potential of AMPHs is associated with their ability to cause mobilization of cytoplasmic dopamine (DA), which leads to an increase in extracellular DA levels. This increase is mediated by the reversal of the DA transporter (DAT) function, which causes non-vesicular DA release, here defined as DA efflux. Notably, inhibition of DA efflux reduces both the ability of AMPH to increase motor activity and AMPH preference8-10. Imbalances in the gut microbiome (dysbiosis) have been suggested to participate in the pathogenesis of substance use disorders11. In addition, psychostimulant abuse promotes dysbiosis12-15. Therefore, it is possible that changes in the gut microbiome and its metabolites may not only be a consequence of substance use disorders, but may play a role in mediating the behavioral responses to drugs of abuse11. Microbial products, such as short-chain fatty acids (SCFAs), are thought to play a fundamental role in regulating the gut-brain axis16. Among SCFAs, butyrate is known to cross the BBB and directly act on neurons and glial cells17. Fusobacterium nucleatum (F. nucleatum) is an anaerobic, filamentous, gram-negative bacterial species that secretes butyrate18, the growth of which is stimulated by AMPH abuse13-15. Our data demonstrate that in germ-free (gnotobiotic) Drosophila, colonization with F. nucleatum enhances AMPH-induced DA effluxes (recorded in isolated fly brains), as well as AMPH behaviors. This potentiation of AMPH actions by F. nucleatum is paralleled by oral administration of butyrate. To understand, mechanistically, how F. nucleatum promotes AMPH actions, it is important to consider that changes in DAT expression regulate both AMPH-induced DA efflux and psychomotor actions19. Also, butyrate is a potent inhibitor of histone deacetylases (HDACs)20-22; inhibition of HDACs robustly increases expression of both DAT mRNA and proteins21-23. Our hypothesis is that F. nucleatum enhances AMPH actions by elevating DAT expression. This is mediated by secretion of butyrate, HDAC inhibition, and enhanced Drosophila DAT (dDAT) promotor acetylation. We will test this hypothesis through the following specific aims: S.A. #1. To determine how F. nucleatum regulates dDAT expression. S.A. #2. To test, mechanistically, how F. nucleatum increases AMPH-induced DA efflux. The experiments of S.A. #1-2 will be performed in isolated Drosophila brains, a model our laboratory developed to study AMPH actions ex vivo. Furthermore, using adult Drosophila, we will be able to translate the molecular discoveries of S.A. #1-2 to specific AMPH behavioral phenotypes. Thus, S.A. #3 focuses on behavior. S.A. #3. To define how F. nucleatum enhances AMPH behaviors.