Regulation of VTA dopamine neurons by AMP kinase

描述（由申请人提供）：从腹侧被盖区（VTA）神经元释放多巴胺有助于学习目标导向行为，并介导大多数药物滥用的愉悦方面。了解VTA神经元的兴奋性如何受到突触输入和膜特性的调节，对于理解多巴胺释放是如何被控制的至关重要。5′-腺苷单磷酸（AMP）活化蛋白激酶（AMPK）是调节细胞代谢的主酶。在外周组织中，AMPK激活增加能量产生同时减少能量消耗的生化途径。虽然在大脑中广泛表达，但其在中枢神经元中的功能尚不清楚。我们实验室的初步数据表明，AMPK的激活剂增强了atp敏感的K+ (K- atp)通道引起的超极化电流，减少了多巴胺D2自受体的脱敏，并抑制了VTA神经元兴奋性突触传递的影响。我们提出的研究的首要假设是AMPK激活增强了对VTA神经元的抑制作用。膜片移液管将用于记录大鼠中脑切片单个VTA神经元的全细胞电流和电位。Western免疫印迹将用于量化在存在和不存在AMPK激活剂和/或抑制剂的情况下培养的中脑切片中磷酸化和未磷酸化AMPK的水平。目的1将描述AMPK激活剂对K- ATP开启剂二氮氧化物引起的电流的影响。Aim #2将研究第二信使系统，并确定介导AMPK激活剂降低多巴胺D2自身受体脱敏能力的递质受体。Aim #3将研究AMPK抑制VTA中谷氨酸介导的突触传递的机制和作用位点。目标4将描述AMPK激活抑制VTA多巴胺神经元突发放电的机制。这些研究结果可能为治疗多巴胺依赖性疾病提供新的药理策略。

DESCRIPTION (provided by applicant): Dopamine release from ventral tegmental area (VTA) neurons assists in learning goal-oriented behaviors and mediates the pleasurable aspects of most drugs of abuse. Understanding how the excitability of VTA neurons is regulated by synaptic inputs and membrane properties is crucial if one is to understand how dopamine release is controlled. 5'-Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a master enzyme that regulates cellular metabolism. In peripheral tissues, AMPK activates biochemical pathways that increase energy production while reducing energy expenditure. Although widely expressed in brain, its function in central neurons is largely unknown. Preliminary data from our lab suggest that activators of AMPK potentiate the hyperpolarizing current evoked by ATP-sensitive K+ (K-ATP) channels, reduce the desensitization of dopamine D2 autoreceptors, and inhibit the influence of excitatory synaptic transmission in VTA neurons. The over-arching hypothesis of our proposed studies is that AMPK activation augments inhibitory influences on VTA neurons. Patch pipettes will be used to record whole-cell currents and potentials in single VTA neurons in slices of rat midbrain. Western immunoblot will be used to quantify levels of phosphorylated and unphosphorylated AMPK in midbrain slices that have been incubated in the presence and absence of AMPK activators and/or inhibitors. Aim #1 will characterize the effect of AMPK activators on currents evoked by the K- ATP opener diazoxide. Aim #2 will investigate second messenger systems and identify transmitter receptors that mediate the ability of AMPK activators to reduce dopamine D2 autoreceptor desensitization. Aim #3 will investigate mechanisms and sites of action by which AMPK inhibits glutamate-mediated synaptic transmission in the VTA. Aim #4 will characterize mechanisms by which AMPK activation inhibits burst firing in VTA dopamine neurons. Results of these studies may suggest new pharmacological strategies for treating dopamine-dependent disorders.