Ethanol-Neurotransmitter Interactions in Brain Neurons

描述（由申请人提供）：该项目的总体具体目标是了解乙醇对大脑通路的作用，介导奖励。腹侧被盖区的多巴胺能神经元（DA-VTA神经元）对于乙醇的强化性质的介导是重要的，并且这些神经元的放电率被乙醇增加。我们已经表明，5-羟色胺增强DA-VTA神经元的乙醇兴奋。我们随后的研究已经调查了DA-VTA神经元的膜中的离子电流，以阐明这种增强的离子机制。在前一个项目期间，我们集中在两个膜电流，可能是5-羟色胺增强，钙依赖性钾电流SK，和混合阳离子电流LH。SK可以通过apamin等药物或细胞内钙的消耗来降低。我们发现，5-羟色胺降低Ih，并产生类似于由apamin产生的尖峰后超极化的变化。在我们的初步研究中，我们发现，同时减少这两个电流产生深刻的增强乙醇的兴奋。我们建立了一个模型来解释这一现象。在拟议的研究中，五个具体的目标将寻求探索乙醇兴奋和5-羟色胺的兴奋增强之间的关系。具体目标#1将建立SK和Ih阻断期间极低浓度乙醇的浓度-响应曲线。具体目标#2将确定乙醇兴奋的5-羟色胺增强是否由SK和Ih的同时减少介导。具体目标#3和#4将确定SK和Ih的阻断如何改变DA-VTA神经元的特定膜性质，以及SK和Ih阻断如何改变乙醇对特定膜性质的影响。具体目标#5将使用细胞内游离钙的成像来确定长期给予5-羟色胺是否消耗细胞内钙储存。这些研究直接建立在我们的有趣的初步观察乙醇增效通过封锁SK和Ih，并将提供重要的信息，如何敏感性乙醇兴奋可能是调制的神经递质对DA-VTA神经元的离子电流的影响。最终，该项目产生的信息可能有助于开发改善酒精中毒的药物疗法。

DESCRIPTION (provided by applicant): The overall specific aims of this project are to understand the action of ethanol on brain pathways that mediate reward. The dopaminergic neurons of the ventral tegmental area (DA-VTA neurons) are important for the mediation of the reinforcing properties of ethanol, and the firing rate of these neurons is increased by ethanol. We have shown that serotonin potentiates ethanol excitation of DA-VTA neurons. Our subsequent studies have investigated ionic currents in the membrane of DA-VTA neurons to elucidate the ionic mechanism of this potentiation. In the previous project period, we focused on two membrane currents that may underlie the serotonin potentiation, the calcium-dependent potassium current SK, and the mixed cationic current lh. SK can be reduced by drugs like apamin or by depletion of intracellular calcium. We found that serotonin reduces Ih, and produces changes in the spike afterhyperpolarization similar to those produced by apamin. In our preliminary studies, we found that concurrent reduction of both of these currents produces profound potentiation of ethanol excitation. We have developed a model to explain this observation. In the proposed studies, five specific aims will seek to explore the relationship between ethanol excitation and potentiation of that excitation by serotonin. Specific Aim #1 will establish the concentration-response curve for very low concentrations of ethanol during blockade of SK and Ih. Specific Aim #2 will ascertain whether serotonin potentiation of ethanol excitation is mediated by concurrent reduction of SK and Ih. Specific Aims #3 and #4 will determine how blockade of SK and Ih alter specific membrane properties of DA-VTA neurons, and how ethanol effects on specific membrane properties are altered by SK and Ih blockade. Specific Aim #5 will use imaging of intracellular free calcium to determine whether prolonged administration of serotonin depletes intracellular stores of calcium. These studies directly build on our interesting initial observations of ethanol potentiation by blockade of SK and Ih, and will provide important information on how sensitivity to ethanol excitation may be modulated by neurotransmitter effects on ionic currents in DA-VTA neurons. Ultimately, information generated by this project may help in the development of pharmacotherapies for the amelioration of alcoholism.