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

描述(由申请人提供)：酒精滥用和依赖仍然是严重的公共卫生问题。因此，更好地了解他们的神经生物学将有助于制定针对预防和/或治疗这些重大健康问题的干预措施。新出现的证据表明，乙醇和药物依赖的许多方面涉及谷氨酸传递的变化。由于谷氨酸转运体1(GLT1)负责摄取细胞外的大部分谷氨酸，我们检验了GLT1功能增强将减少酒精嗜好大鼠(P鼠)乙醇摄取的假设。在P大鼠长期暴露于自由选择的乙醇(15%和30%)5周后，给它们注射头孢曲松(I.P.)，这是一种已知可提高GLT1表达的β-内酰胺类抗生素，连续5天。我们发现，与接受生理盐水载体治疗的大鼠相比，接受头孢曲松治疗的P鼠在治疗期间显示出乙醇摄入量的减少。然而，头孢曲松的长期疗效尚不清楚。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)在慢性乙醇暴露的两个不同时间点对P鼠减少乙醇摄入的长期影响。我们还将研究GLT1激活对Wistar大鼠饮酒行为的影响作为对照。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，可以减少P和Wistar大鼠的乙醇消耗。乙醇剥夺效应，我们将采用，已被用来评估复发的大鼠的行为。在目标2中，我们的工作假设是，当动物再次接触乙醇时，戒断期间GLT1功能的增加将减少复发行为。头孢曲松的最低受试量(25 mg/kg)并未显示GLT1表达增加，但也有效地减少了乙醇的摄入量。这些发现表明，头孢曲松可能对GLT1有其他药理作用，或者可能通过另一种机制起作用(功能增加可能涉及几种机制中的一种改变)。因此，我们在目标3中建议确定涉及头孢曲松或GPI-1046上调GLT1表达的信号通路。此外，我们的目标是确定头孢曲松、GPI-1046和MS-153的分子作用机制，这可能涉及通过关键蛋白的磷酸化激活GLT1功能。这项提议产生的发现将提供大量关于GLT1在调节乙醇消耗中的作用的信息，并将为寻找潜在的酒精成瘾治疗靶点铺平道路。 公共卫生相关性：这项提案的目标是调查谷氨酸转运体--一种神经递质转运体--在酒精依赖中的作用。这种化学转运体在饮酒行为中起着重要作用。通过这项研究，我们旨在提供有关该转运蛋白在减少酒精消耗中的作用的充分信息，并希望为实现酒精依赖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.