Electrochemical Analysis of Dendritic Dopamine Release

描述（由申请人提供）：多巴胺（DA）是大脑运动和情感通路中的关键递质。多巴胺能神经传递的功能障碍是对社会有重要影响的各种脑部疾病的基础，包括帕金森病和亨廷顿病、精神分裂症和成瘾。中脑中的DA细胞群为CNS提供DA的主要来源。黑质腹侧被盖区（VTA）的黑质神经元向背侧纹状体（黑质纹状体DA系统）投射，而邻近的腹侧被盖区（VTA）的黑质神经元向中脑边缘核（中脑边缘DA系统）投射。DA神经元的一个潜在的独特特征是它们从中脑的树突以及从远处的轴突终末释放DA。DA在树突和终末的释放对DA介导的行为至关重要，但对中脑DA释放的调控因素知之甚少。使用碳纤维微电极和快速扫描循环伏安法检测诱发DA释放在实时脑切片中，我们已经发现显着差异的钙依赖性和钙通道所需的树突状与终端释放。此外，我们已经发现了不同的模式的调节作用在SNc，腹侧被盖区和纹状体的离子型受体的谷氨酸和GABA。值得注意的是，我们还发现了一种新的黑质纹状体DA释放的内源性调节剂：活性氧（ROS），H2 O2。在这一延续中，我们将研究树突状DA释放的不同Ca 2+依赖性，重点是从突触输入DA细胞和释放的Ca 2+从细胞内存储（目的I）的贡献。我们还将阐明ROS作为树突和末端DA溢出的调节剂的作用（目的II-IV）。目的II将检查H2 O2和其他ROS在黑质纹状体与中脑边缘DA系统中的参与。目的研究活性氧的来源，包括DA释放位点附近的细胞和末梢。目的IV将测试H202是否通过引起DA细胞的超极化来抑制树突状DA溢出;将通过全细胞记录来指示对膜性质的影响。

DESCRIPTION (provided by applicant): Dopamine (DA) is a key transmitter in motor and emotive pathways of the brain. Dysfunction of dopaminergic neurotransmission underlies a variety of brain disorders that have a critical impact on society, including Parkinson's and Huntington's diseases, schizophrenia, and addiction. DA cell groups in the midbrain provide the primary source of DA to the CNS. Cells of the substantia nigra pars compacta (SNc) project rostrally to innervate the dorsal striatum (nigrostriatal DA system) whereas those of the adjacent ventral tegmental area (VTA) project to the nucleus accumbens and other limbic structures (mesolimbic DA system). A potentially unique characteristic of DA neurons is that they release DA from their dendrites in midbrain, as well as from distant axon terminals. Dendritic, as well as terminal release of DA is critical for DA-mediated behaviors, yet little is known about factors that regulate DA release In midbrain. Using carbon-fiber microelectrodes and fast-scan cyclic voltammetry to detect evoked DA release in real-time in brain slices, we have found significant differences in the Ca2+-dependence and Ca2+-channels required for dendritic vs. terminal release. Further, we have found distinct patterns of regulation by glutamate and GABA acting at ionotropic receptors in SNc, VTA and striatum. Significantly, we also discovered a novel, endogenous regulator of the nigrostriatal DA release: the reactive oxygen species (ROS), H202. In this continuation, we will investigate the distinct Ca2+ dependence of dendritic DA release, with emphasis on contributions from synaptic input to DA cells and release of Ca2+ from intracellular stores (Aim I). We will also elucidate the role of ROS as modulators of dendritic and terminal DA overflow (Aim ll-IV). Aim II will examine the involvement of H202 and other ROS in nigrostriatal vs. mesolimbic DA systems. Aim Ill will investigate sources of ROS, including terminals and cells adjacent to DA release sites. Aim IV will test whether H202 inhibits dendritic DA overflow by causing hyperpolarization of DA cells; effects on membrane properties will be indicated by whole cell recording.