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.

整合神经科学实验室（LIN）研究的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研究酒精对NMDA和非NMDA谷氨酸受体功能的影响。我们已经使用了靶向基因的NR2A - / - 小鼠来检查包含或缺乏NR2A亚基的NMDA受体的乙醇抑制。 NR2A - / - 小鼠的神经元中NMDAR的乙醇抑制作用增强了，而在小脑颗粒细胞中，这种作用比在皮质神经元中更明显。我们还正在进行研究，以检查对自动神经元培养物中突触和非突触NMDA受体的酒精影响。在此准备中，我们还将检查对突触和非突触池之间NMDAR贩运的饮酒影响。最近的发现还表明，乙醇与对AMPA型谷氨酸受体的动作相互作用。 我们继续研究背纹状体中的突触可塑性，并正在研究海马和杏仁核中类似的塑性变化。我们已经表明，内源性大麻素充当激活前CB1大麻素受体的逆行信号，在开始纹状体长期突触抑郁症（LTD）中起着关键作用。我们积累了证据表明，内源性大麻素是通过涉及anandamide膜转运蛋白系统的“向后转移”从突触后神经元释放的。我们还检查了出生后的突触可塑性的另一种内源性大麻素依赖性形式，去极化诱导的海马CA1神经元中抑制（DSI）的抑制作用。 DSI开始以〜p14-p16的形式表达，我们有证据表明，DSI的出现可能是由于CA1锥体神经元中内源性大麻素生产机制的发展所致。有趣的是，DSI参与的内源性大麻素的释放似乎并不涉及与LTD诱导有关的运输系统。 我们还开始探索杏仁核和纹状体神经元的内源性大麻素生产中涉及的分子机制，并使用新近实现的技术将神经元与附着的Gabaeragric Synaptic Boutons分离。使用HPLC和质谱联合的研究表明，D2多巴胺受体与去极化和谷氨酸受体激活结合使用，增强了纹状体中内源性大麻素吻合的产生。我们还使用了这些技术来表征纹状体仙境化水平的发育增加，这似乎与视觉感觉输入的发作有关。当前的实验正在探索增强的内源性大麻素水平与皮质纹状体突触中突触可塑性的发育变化之间的联系。 生化研究的目的是了解将受体激活与可塑性诱导联系起来的细胞内信号，并确定持续抑郁症和DSI涉及的机制。我们已经观察到ERK型MAP激酶的CB1受体激活主要是通过抑制腺苷酸环化酶来介导的。我们希望确定该途径是否在突触前终端中活跃。我们还正在研究CB1激活对突触前囊泡相关蛋白的磷酸化和功能的影响，以开始了解该受体如何产生神经递质分泌的持续变化。 我们正在检查的受体是滥用药物的靶标，并在与成瘾有关的神经元途径中起着突出作用。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过程中在寻求药物和突触可塑性中的作用。 安德鲁·霍尔姆斯（Andrew Holmes）博士接受了行为科学与遗传学部分（SBSG）的代理主管的立场。他将使用靶向基因的小鼠进行研究，以检查酒精和药物滥用的分子基础，以及胁迫 - 酒精相互作用。结构生物学（SB）的部分将在未来两年内建立，以允许研究膜蛋白结构和酒精与膜蛋白的相互作用。