CELLULAR & BIOCHEMICAL MECHANISMS UNDERLYING MOSSY FIBER LONG TERM POTENTIATION

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• 批准号: 6495434
• 负责人: ROBERT C MALENKA
• 金额: $ 22.55万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6495434
• 关键词: cyclic AMP; endocytosis; exocytosis; fluorescent dye /probe; guinea pigs; laboratory mouse; long term potentiation; mossy fiber; nerve /myelin protein; neural plasticity; neurotransmitter transport; neurotrophic factors; phosphoproteins; protein kinase A; tissue /cell culture

Long-lasting, activity-dependent changes in the strength of synaptic transmission play a critical role in the development of neural circuits and in the storage of information. Such changes also appear to play an important role in the recovery of the brain from a variety of pathological insults. The most compelling and extensively studied model for such changes has been that form of long-term potentiation (LTP) observed in hippocampal CAl pyramidal cells. It is clear, however, that there are many forms of synaptic plasticity and that their underlying mechanisms differ. The primary goal of this project is to elucidate the molecular mechanisms underlying the novel form of LTP observed at the synapses between mossy fibers and hippocampal CA3 pyramidal cells (MF LTP). Unlike the LTP in CAl cells, MF LTP does not require activation of NMDA receptors but appears to be induced by presynaptic activation of the cAMP-dependent protein kinase (PKA) resulting in a long-lasting increase in neurotransmitter release. A number of different physiological and biochemical approaches will be used to examine MF LTP. Because MF LTP can be generated in single cell cultures of dentate granule cells, it will be possible to directly monitor changes in synaptic vesicle exocytosis and endocytosis using the fluorescent dye FMl-43. Biochemical assays will be used to monitor the time course of changes in cAMP levels and PKA activity during MF LIP as well as to determine whether specific presynaptic phosphoproteins, in particular rabphilin 3A, may be involved in this form of plasticity. A complementary set of experiments will examine MF LTP in a line of mutant mice which is lacking the specific presynaptic protein, rab3A. Because neurotrophins appear to play an important role in experience-dependent cortical plasticity and also cause long-lasting increases in neurotransmitter release, their synaptic actions will be examined and compared to MF LTP. An examination and comparison of MF LIP and the synaptic actions of neurotrophins will markedly enhance our understanding of the basic mechanisms of synaptic plasticity in the mammalian brain. This in turn will facilitate the development of interventions that will either prevent or promote recovery from the pathological insults accompanying a number of neurologic disorders such as stroke and epilepsy.

突触强度的持久、依赖于活动的变化 传输在神经回路的发育中起着至关重要的作用 以及信息的存储。这些变化似乎也起到了 对大脑从各种病理状态中恢复具有重要作用 侮辱。最引人注目和最广泛研究的模型 变化是观察到的长时程增强（LTP）形式 海马 CA1 锥体细胞。但很明显，有很多 突触可塑性的形式及其潜在机制有所不同。 该项目的主要目标是阐明分子机制 在苔藓之间的突触中观察到的新型 LTP 形式的基础 纤维和海马 CA3 锥体细胞 (MF LTP)。与 CA 中的 LTP 不同 细胞中，MF LTP 不需要激活 NMDA 受体，但似乎 由 cAMP 依赖性蛋白激酶的突触前激活诱导 （PKA）导致神经递质释放的持久增加。一个 将使用许多不同的生理和生化方法 检查 MF LTP。因为 MF LTP 可以在单细胞培养物中产生 齿状颗粒细胞的变化，将有可能直接监测变化 使用荧光染料进行突触小泡胞吐作用和内吞作用 FML-43。生化检测将用于监测时间进程 MF LIP 期间 cAMP 水平和 PKA 活性的变化以及 确定是否存在特定的突触前磷蛋白，特别是 rabphilin 3A，可能参与这种形式的可塑性。一个互补的 一组实验将检查一系列突变小鼠中的 MF LTP 缺乏特定的突触前蛋白 rab3A。因为神经营养素 似乎在经验依赖的皮层中发挥着重要作用 可塑性，也会导致神经递质的长期增加 释放后，将检查它们的突触作用并与 MF LTP 进行比较。 MF LIP 和突触作用的检查和比较 神经营养素将显着增强我们对基本神经营养物质的理解 哺乳动物大脑中突触可塑性的机制。这反过来 将促进干预措施的制定，以防止 或促进从伴随着一些疾病的病理损伤中恢复 神经系统疾病，如中风和癫痫。