Electrochemical Analysis of Dendritic Dopamine Release

描述(申请人提供)：多巴胺(DA)是大脑运动和情绪通路的关键递质。多巴胺能神经传递功能障碍是对社会产生严重影响的各种大脑疾病的基础，包括帕金森氏症和亨廷顿病、精神分裂症和成瘾。中脑DA细胞群是中枢多巴胺的主要来源。黑质致密部(SNC)的细胞投射到背侧纹状体(黑质纹状体DA系统)，而邻近腹侧被盖区(VTA)的细胞投射到伏隔核和其他边缘结构(中脑边缘DA系统)。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远处的轴突终末释放DA。DA的树突状和终末释放对DA介导的行为至关重要，但对调节中脑DA释放的因素知之甚少。使用碳纤维微电极和快速扫描循环伏安法实时检测脑片中诱发的DA释放，我们发现树突和终末释放所需的钙依赖和钙通道存在显著差异。此外，我们还发现谷氨酸和GABA对SNc、VTA和纹状体的亲离子受体有明显的调节作用。值得注意的是，我们还发现了黑质纹状体DA释放的一种新的内源性调节因子：活性氧物种(ROS)，H202。在本文中，我们将研究树突状DA释放的不同的钙依赖性，重点是突触对DA细胞的输入和细胞内库释放的钙(目标I)。我们还将阐明ROS作为树突和末端DA溢出的调节器(AIM 11-IV)的作用。AIM II将研究H202和其他ROS在黑质纹状体与中边缘DA系统中的参与。Aim Ill将调查ROS的来源，包括DA释放部位附近的终端和细胞。目的IV将测试H202是否通过引起DA细胞超极化来抑制树突状DA溢出；对膜特性的影响将通过全细胞记录来指示。

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.