CREB, Alcohol Reward and Consumption in ENT1 Null Mice

描述（由申请人提供）：乙醇抑制培养细胞中的1型平衡核苷转运蛋白（ENT1）。对ENT1缺失小鼠的初步研究表明，由于ENT1缺失小鼠对乙醇的急性反应较弱，因此ENT1也是乙醇在体内的靶点。ENT1缺失小鼠也比野生型小鼠消耗更多的乙醇。初步研究表明，谷氨酸驱动的CREB激活在ENT1缺失小鼠纹状体中增加。这似乎是由于纹状体突触前腺苷A1受体的激活减少，这是由于电生理研究测量到的腺苷张力降低。由于纹状体CREB激活与药物奖励减少有关，ENT1缺失小鼠过量饮酒可能与对乙醇奖励的耐受性有因果关系。与这一假设相一致，条件位置偏好研究表明，ENT1缺失小鼠对乙醇配对侧（2.0 g/kg）的偏好明显低于野生型小鼠。该提案将在初步研究的基础上进行扩展，并检查CREB信号在调节ENT1缺失小鼠对酒精的行为反应中的作用。首先，初始敏感性，急性和慢性耐受性，操作性自我给药和场所条件反射试验将用于检查乙醇耐受性，以及乙醇的奖励和强化效应。其次，使用CREB - lacz报告小鼠，并通过检测ENT1缺失小鼠纹状体中两个CREB驱动基因（脑啡肽和肌啡肽）的表达，在特定细胞中鉴定CREB活性的增加。第三，将使用pCREB免疫反应性来测量纹状体脑切片中的CREB活性，以确定导致ENT1缺失小鼠基础CREB活性增加的信号通路。最后，我们将确定在ENT1缺失小鼠中，纹状体pCREB增加的信号通路的改变是否有助于对乙醇奖励效应的耐受性和乙醇消耗的增加。该项目的目标是了解ENT1缺失小鼠酒精饮酒行为增强的信号通路，并确定酒精中毒的新治疗靶点。

DESCRIPTION (provided by applicant): Ethanol inhibits the type 1 equilibrative nucleoside transporter (ENT1) in cultured cells. Preliminary studies with ENT1 null mice indicate that ENT1 is also a target for ethanol in vivo since ENT1 null mice are less responsive to acute effects of ethanol. ENT1 null mice also consume more ethanol than wild type littermates. Preliminary studies demonstrate that glutamate-driven CREB activation was increased in the striatum of ENT1 null mice. This appears to result from diminished activation of striatal presynaptic adenosine A1 receptors due to reduced adenosine tone as measured by electrophysiological studies. Since striatal CREB activation is associated with reduced drug reward, excessive ethanol drinking in ENT1 null mice may be causally related to tolerance to ethanol reward. Consistent with this hypothesis, a conditioned place preference study demonstrated that ENT1 null mice prefer the ethanol-paired side (2.0 g/kg) significantly less than wild type mice. This proposal will expand upon preliminary studies and examine the role of CREB signaling in regulating behavioral responses to alcohol in ENT1 null mice. First, initial sensitivity, acute and chronic tolerance, operant self-administration, and place conditioning assays will be used to examine ethanol tolerance, and rewarding and reinforcing effects of ethanol. Second, increases in CREB activity will be identified in specific cells using CRE-lacZ reporter mice and by examining expression of two CRE-driven genes, enkephalin and dynorphin, in the striatum of ENT1 null mice. Third, pCREB immunoreactivity will be used to measure CREB activity in striatal brain slices to identify signaling pathways that contribute to increased basal CREB activity in ENT1 null mice. Finally, we will determine whether alterations in signaling pathways that account for increased striatal pCREB contribute to tolerance to rewarding effects of ethanol and increased ethanol consumption in ENT1 null mice. The goal of this project is to understand signaling pathways underlying enhanced alcohol drinking behavior in ENT1 null mice and to identify novel therapeutic targets for alcoholism.