CELLULAR & BIOCHEMICAL MECHANISMS UNDERLYING MOSSY FIBER LONG TERM POTENTIATION

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• 批准号: 6359663
• 负责人: ROBERT C MALENKA
• 金额: $ 14.82万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2001-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6359663
• 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.

突触强度的长期、活动依赖性变化 传输在神经回路的发展中起着关键作用 以及信息的存储。这种变化似乎也起到了一种 在大脑从各种病理性损伤中恢复的重要作用 侮辱。最引人注目和广泛研究的模型， 这种变化是在脑组织中观察到的长时程增强（LTP）形式。 海马CA 1区锥体细胞。然而，很明显， 突触可塑性的形式和它们的潜在机制不同。 本项目的主要目标是阐明 潜在的LTP的新形式观察到的突触之间的苔藓 海马CA 3区锥体细胞（MF LTP）。与CAl中的LTP不同， 细胞，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长期增加。一 将使用许多不同的生理学和生物化学方法 检查MF LTP由于MF LTP可以在单细胞培养中产生， 将有可能直接监测 使用荧光染料在突触小泡的胞吐和胞吞中 FM1 -43将使用生化测定来监测 MF LIP期间cAMP水平和PKA活性的变化以及 确定特定的突触前磷蛋白， rabphilin 3A可能参与这种形式的可塑性。互补 一组实验将在一个突变小鼠系中检查MF LTP， 缺乏特异的突触前蛋白rab 3A。因为神经营养因子 似乎在经验依赖性皮层中起着重要作用， 可塑性，也会导致神经递质的长期增加， 释放，他们的突触行动将被检查和比较MF LTP。 MF-LIP与神经元突触作用的比较研究 神经营养素将显著增强我们对神经营养素的基本 哺乳动物大脑中突触可塑性的机制。这反过来 将促进干预措施的发展， 或促进从伴随着许多疾病的病理损伤中恢复， 神经系统疾病，如中风和癫痫。