The Role of the Dopamine Transporter in Psychostimulant Abuse

摘要 苯丙胺类药物（AMPHs）是一种精神兴奋剂，常用于治疗神经精神疾病。 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。滥用可能性 AMPH的表达与其引起细胞质多巴胺（DA）动员的能力有关，这导致 导致细胞外DA水平升高。这种增加是由DA转运蛋白（DAT）的逆转介导的 引起非囊泡性DA释放的功能，此处定义为DA流出。值得注意的是，DA外排的抑制降低了 AMPH增加运动活性的能力以及AMPH偏好性3，6，9。 有研究表明，肠道菌群的失衡（生态失调）参与了消化道溃疡的发病机制。 药物使用障碍11.与这一观点一致的是，精神兴奋剂的滥用会导致生命力失调12 -15。因此，我们认为， 肠道微生物组及其代谢物的变化可能不仅是物质 使用障碍，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）被怀疑在脂肪酸代谢中起着重要作用。 肠-脑轴。在SCFA中，已知丁酸盐可穿过血脑屏障并直接作用于神经元和神经胶质细胞16。 具核梭杆菌（Fusobacterium nucleatum, F. nucleatum）是厌氧的丝状革兰氏阴性细菌物种，其 分泌丁酸盐17，其生长受到AMPH滥用的刺激13 -15。 我们的初步数据表明，在固氮果蝇中，胃肠道的定殖 与F. nucleatum增强AMPH诱导的DA流出（在离体蝇脑中记录），以及AMPH 相关的行为。这种增强作用由F.核仁素与口服给药平行 SCFA丁酸酯的含量。这些数据表明F.神经元核团和丁酸 AMPH的性质。为了理解，机械地，如何F。细胞核促进AMPH作用，这是重要的 考虑调节AMPH诱导DA外排和AMPH精神运动的DAT表达的变化 行动19.而且，丁酸盐是组蛋白脱乙酰酶（HDACs）20-22的有效抑制剂， 特别是HDAC 1，可显著增加DAT mRNA和蛋白质的表达21，22。 我们的假设是F. nucleatum通过提高DAT表达增强AMPH作用。这是介 通过丁酸盐分泌和HDAC抑制。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.核仁支持AMPH诱导的DA外排。 这些实验将在黑腹果蝇的离体脑中进行，黑腹果蝇是我们的一种动物模型。 用于研究体内AMPH作用实验室。利用这个模型，我们就能将分子 S.A.的发现#1至特定的AMPH行为表型。因此，S.A.第二个重点是行为： S.A. #2.为了确定F. nucleatum对AMPH诱导行为的影响。

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 has been associated to 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 that 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 as well as AMPH preference3, 6, 9. It has been suggested that imbalance in the gut microbiome (dysbiosis) participates in the pathogenesis of substance use disorders11. Consistent with this idea, 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 behavioral responses to drugs of abuse11. Microbial products such as short-chain fatty acids (SCFAs) are suspected to play a fundamental role in the gut-brain axis. Among SCFAs, butyrate is known to cross the BBB and directly act on neurons and glial cells16. Fusobacterium nucleatum (F. nucleatum) is an anaerobic filamentous gram-negative bacterial species that secretes butyrate17, growth of which is stimulated by AMPH abuse13-15. Our preliminary data demonstrate that in gnotobiotic Drosophila, colonization of the gastrointestinal track with F. nucleatum enhances AMPH-induced DA effluxes (recorded in isolated fly brains), as well as AMPH associated behaviors. This potentiation of AMPH actions by F. nucleatum was paralleled by oral administration of the SCFA butyrate. These data point to a powerful role of both F. nucleatum and butyrate in the psychomotor properties of AMPH. 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 AMPH psychomotor actions19. Also, butyrate is a potent inhibitor of histone deacetylases (HDACs)20-22 and inhibition of HDACs, specifically HDAC1, robustly increases expression of both DAT mRNA and proteins21, 22. Our hypothesis is that F. nucleatum enhances AMPH actions by elevating DAT expression. This is mediated by secretion of butyrate and HDAC inhibition. We will test this hypothesis through the following specific aims: S.A. #1. To determine how F. nucleatum supports AMPH-induced DA efflux. These experiments will be performed in isolated brains of Drosophila melanogaster, an animal model our laboratory developed to study AMPH actions in vivo. Using this model, we will be able to translate the molecular discoveries of S.A. #1 to specific AMPH behavioral phenotypes. Thus, S.A. #2 focuses on behavior: S.A. #2. To determine the effect of F. nucleatum on AMPH-induced behaviors.