The role of GLT1 in the modulation of alcohol-drinking behavior in P rats.

描述（由申请人提供）：酒精（EtOH）滥用和依赖仍然是重大的公共卫生问题。因此，更好地了解他们的神经生物学将促进针对预防和/或治疗这些主要健康问题的干预措施的发展。新出现的证据表明，EtOH和药物依赖的许多方面都涉及谷氨酸传递的变化。由于谷氨酸转运蛋白1 （GLT1）负责大部分细胞外谷氨酸的摄取，我们验证了GLT1功能增加会减少酒精偏好大鼠（P大鼠）EtOH消耗的假设。在P大鼠长期自由暴露于EtOH(15%和30%)5周后，连续5天给予头孢曲松（i.p），一种已知可提高GLT1表达的β -内酰胺类抗生素。我们发现，与接受生理盐水的大鼠相比，头孢曲松治疗的P大鼠在治疗期间EtOH摄入量减少。然而，头孢曲松的长期效果尚不清楚。在这里，我们将测试头孢曲松和其他已知激活GLT1的药物（GPI-1046和MS-153）在P大鼠慢性EtOH暴露的两个不同时间点对EtOH摄入衰减的长期影响。我们还将研究GLT1激活对Wistar大鼠etoh饮酒行为的影响，作为比较对照组。我们在目标1中的工作假设是，GLT1功能的增加，通过上调或激活，减弱了P和Wistar大鼠的EtOH消耗。我们将使用EtOH剥夺效应来评估P大鼠的类似复发行为。在目标2中，我们的工作假设是，当动物再次暴露于EtOH时，戒断期GLT1功能的增加将减少复发样行为。最低剂量的头孢曲松（25 mg/kg）没有显示GLT1表达的增加，也有效地减少了EtOH的摄入量。这些发现表明头孢曲松可能对GLT1有其他药理作用或可能通过其他机制起作用（功能增加可能涉及几种机制之一的改变）。因此，我们在目的3中提出确定头孢曲松或GPI-1046参与上调GLT1表达的信号通路。此外，我们旨在确定头孢曲松、GPI-1046和MS-153的分子作用机制，可能通过磷酸化关键蛋白激活GLT1功能。这项研究的结果将为GLT1在EtOH消耗调节中的作用提供充足的信息，并为寻找酒精成瘾的潜在治疗靶点铺平道路。

DESCRIPTION (provided by applicant): Alcohol (EtOH) abuse and dependence continue to be significant public health problems. Thus, a better understanding of their neurobiology will facilitate the development of interventions targeting prevention and/or treatment of these major health issues. Emerging evidence indicates that many aspects of EtOH and drug dependence involve changes in glutamate transmission. Because glutamate transporter 1 (GLT1) is responsible for the uptake of the majority of extracellular glutamate, we tested the hypothesis that increased GLT1 function would attenuate EtOH consumption in alcohol-preferring rats (P rats). After P rats had been chronically exposed to a free choice of EtOH (15 and 30%) for five weeks, they were administered ceftriaxone (i.p.), a beta-lactam antibiotic known to elevate GLT1 expression, for five consecutive days. We found that ceftriaxone-treated P rats showed a reduction in EtOH intake for the duration of treatment as compared to rats that received a saline vehicle. The long-term effects of ceftriaxone, however, are unknown. Here, we will test the long-term effects of ceftriaxone and other drugs (GPI-1046 and MS-153) known to activate GLT1 in the attenuation of EtOH intake at two different time points of chronic EtOH exposure in P rats. We will also investigate the effects of GLT1 activation in EtOH-drinking behavior in Wistar rats as comparison control groups. Our working hypothesis in aim 1 is that an increase in GLT1 function, via up- regulation or activation, attenuates EtOH consumption in both P and Wistar rats. The EtOH deprivation effect, which we will employ, has been used to assess relapse-like behavior in P rats. In aim 2, our working hypothesis is that an increase in GLT1 function during withdrawal periods will reduce relapse-like behavior when animals are re-exposed to EtOH. The lowest tested dose of ceftriaxone (25 mg/kg), which did not show an increase in GLT1 expression, was also effective in reducing EtOH intake. These findings suggest that ceftriaxone may have other pharmacological effects on GLT1 or may act by another mechanism (a functional increase may involve a change in one of several mechanisms). Thus, we propose in aim 3 to determine the signaling pathways involving ceftriaxone or GPI-1046 in up-regulation of GLT1 expression. Moreover, we aim to determine the molecular mechanisms of action of ceftriaxone, GPI-1046 and MS-153, which may involve activation of GLT1 function through phosphorylation of key proteins. The findings generated from this proposal will provide ample information about the role of GLT1 in the regulation of EtOH consumption and will pave the path toward finding a potential therapeutic target for alcohol addiction. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to investigate the role of glutamate transporter, a neurotransmitter transporter, in alcohol dependence. This chemical transporter plays an important role in alcohol-drinking behavior. From this study, we aim to provide ample information about the role of this transporter in the reduction of alcohol consumption and hope to pave the path toward potential therapeutic targets for alcohol dependence.