Synaptic Transmission: Modulation, Plasticity And Effect

突触传递：调节、可塑性和效应

• 批准号: 6818692
• 负责人: David M Lovinger
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON ALCOHOL ABUSE AND ALCOHOLISM
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6818692
• 关键词: AMPA receptors; Rodentias; alcoholism /alcohol abuse; anandamide; biological signal transduction; brain mapping; cannabinoid receptor; drug abuse; electrophysiology; glutamate receptor; hippocampus; laboratory mouse; neural plasticity; neurochemistry; neuropharmacology; neurophysiology; receptor expression; stress; synapses

The focus of research in the Laboratory of Integrative Neuroscience (LIN) is the determination of mechanisms underlying neuromodulation and plasticity and the effects of alcohol and other drugs of abuse on these neuronal functions. Ongoing studies are examining alcohol effects on NMDA and non-NMDA glutamate receptor function. We have used gene-targeted NR2A-/- mice to examine ethanol inhibition of NMDA receptors that contain or lack the NR2A subunit. Ethanol inhibition of NMDARs is enhanced in neurons from NR2A-/- mice, and this effect is more pronounced in cerebellar granule cells than in cortical neurons. We are also undertaking studies to examine alcohol effects on synaptic versus non-synaptic NMDA receptors in autaptic neuronal cultures. We will also examine alcohol effects on NMDAR trafficking between synaptic and non-synaptic pools in this preparation. Recent findings also indicate that ethanol interacts with cyclothiazide actions on AMPA-type glutamate receptors. We have continued studies of synaptic plasticity in dorsal striatum, and are also investigating similar plastic changes in hippocampus and amygdala. We have shown that endocannabinoids, acting as retrograde signals that activate presynaptic CB1 cannabinoid receptors, play a key role in initiation of striatal long-term synaptic depression (LTD). We have accumulated evidence that the endocannabinoids are released from postsynaptic neurons via "backward-transport" involving an anandamide membrane transporter system. We have also examined postnatal development of another endocannabinoid-dependent form of synaptic plasticity, depolarization-induced suppression of inhibition (DSI) in hippocampal CA1 neurons. DSI begins to be expressed at ~P14-P16, and we have evidence that the appearance of DSI is probably due to development of endocannabinoid production mechanisms in CA1 pyramidal neurons. Interestingly, release of endocannabinoids involved in DSI does not appear to involve the transport system implicated in LTD induction. We have also begun to explore the molecular mechanisms involved in endocannabinoid production leading to DSI and LTD in amygdala and striatal neurons using newly-implemented techniques for isolating neurons with attached GABAergic synaptic boutons. Studies using combined HPLC and mass spectrometry have indicated that D2 dopamine receptors, in conjunction with depolarization and glutamate receptor activation, enhance production of the endocannabinoid anandamide in striatum. We have also used these techniques to characterize developmental increases in striatal anandamide levels that appear to be tied to the onset of visual sensory input. Current experiments are exploring the link between enhanced endocannabinoid levels and developmental changes in synaptic plasticity at corticostriatal synapses. Biochemical studies are aimed at understanding the intracellular signals that link receptor activation to induction of plasticity, and determining the mechanisms involved in long-lasting depression and DSI. We have observed that CB1 receptor activation of the ERK-type MAP kinase is mediated predominantly through inhibition of adenylyl cyclase. We hope to determine if this pathway is active in presynaptic terminals. We are also examining effects of CB1 activation on phosphorylation and function of presynaptic vesicle-associated proteins to begin to understand how this receptor may produce lasting alterations in neurotransmitter secretion. The receptors we are examining are targets for drugs of abuse and play prominent roles in neuronal pathways implicated in addiction. In the long-term we are interested in gaining a better understanding of the role of these receptors in drug-seeking and synaptic plasticity during the development of drug tolerance and dependence, as well as addiction. Dr. Andrew Holmes has accepted the position of Acting Chief of the Section on Behavioral Science and Genetics (SBSG). He will initiate studies using gene-targeted mice to examine the molecular basis of alcohol and drug abuse, as well as stress-alcohol interactions. The Section on Structural Biology (SB) that will be set up within the next two years to allow studies of membrane protein structure and alcohol interactions with membrane proteins.

综合神经科学实验室（LIN）的研究重点是确定神经调节和可塑性的机制以及酒精和其他滥用药物对这些神经元功能的影响。正在进行的研究正在检查酒精对NMDA和非NMDA谷氨酸受体功能的影响。我们已经使用基因靶向NR 2A-/-小鼠来检查含有或缺乏NR 2A亚基的NMDA受体的乙醇抑制。NR 2A-/-小鼠神经元中NMDAR的乙醇抑制增强，并且这种作用在小脑颗粒细胞中比在皮质神经元中更明显。我们也正在进行研究，以检查酒精对突触与非突触NMDA受体在autaptic神经元文化的影响。我们还将研究酒精对突触和非突触池之间NMDAR运输的影响。最近的研究结果还表明，乙醇与环噻嗪对AMPA型谷氨酸受体的作用相互作用。 我们继续研究背侧纹状体的突触可塑性，也在研究海马和杏仁核的类似可塑性变化。我们已经证明，内源性大麻素，作为逆行信号激活突触前CB 1大麻素受体，在启动纹状体长时程突触抑制（LTD）中发挥关键作用。我们已经积累的证据表明，内源性大麻素释放突触后神经元通过“向后运输”涉及大麻素膜转运系统。我们还研究了另一种内源性大麻素依赖形式的突触可塑性，去极化诱导抑制（DSI）在海马CA 1神经元的出生后发展。DSI在~P14-P16开始表达，并且我们有证据表明DSI的出现可能是由于CA 1锥体神经元中内源性大麻素产生机制的发展。有趣的是，参与DSI的内源性大麻素的释放似乎并不涉及LTD诱导所涉及的运输系统。 我们还开始探索参与内源性大麻素产生的分子机制，导致杏仁核和纹状体神经元中的DSI和LTD，使用新实施的技术分离具有附加GABA能突触终扣的神经元。使用组合HPLC和质谱法的研究表明，D2多巴胺受体与去极化和谷氨酸受体活化一起增强纹状体中内源性大麻素anandamide的产生。我们还使用这些技术来表征纹状体anandamide水平的发育增加，这似乎与视觉感官输入的发生有关。目前的实验正在探索增强内源性大麻素水平和皮质纹状体突触可塑性发育变化之间的联系。 生物化学研究旨在了解将受体激活与可塑性诱导联系起来的细胞内信号，并确定涉及持久抑郁和DSI的机制。我们已经观察到，CB 1受体激活的ERK型MAP激酶介导的腺苷酸环化酶的抑制主要是通过。我们希望确定这条通路在突触前末梢是否活跃。我们也在研究CB 1激活对突触前囊泡相关蛋白磷酸化和功能的影响，以开始了解这种受体如何在神经递质分泌中产生持久的改变。 我们正在研究的受体是药物滥用的靶点，在成瘾的神经通路中起着重要作用。从长远来看，我们有兴趣更好地了解这些受体在药物耐受性和依赖性以及成瘾发展过程中的药物寻求和突触可塑性中的作用。 博士安德鲁·霍姆斯接受了行为科学和遗传学科（SBSG）代理科长的职位。他将启动使用基因靶向小鼠的研究，以研究酒精和药物滥用的分子基础，以及压力-酒精相互作用。结构生物学部分（SB）将在未来两年内成立，以研究膜蛋白结构和酒精与膜蛋白的相互作用。