PRE AND POSTSYNAPTIC CELLULAR MECHANISMS OF LTP

了解学习和记忆的机制是一个基本的 突触的神经生物学和细胞修饰中的问题 传输被认为是学习的基础。 脊椎动物中枢神经系统中的快速突触传递 很大程度上是由氨基酸的释放介导的。该传输 受到许多修饰影响，包括长时程增强 （LTP）。LTP被定义为突触效能的增加持续 小时或更长时间，由短暂的高频刺激引发 （破伤风）到突触。这种现象在多巴胺能神经系统中普遍存在。 脊椎动物大脑中的突触，包括七鳃鳗的菱脑。 LTP的这种形式与哺乳动物的LTP有许多共同之处， 海马，包括谷氨酸受体和突触后的作用 钙通量为了研究LTP的细胞方面， 制备提供了明显的优点。七鳃鳗的体型很大， 突触终末使它们可用于指导细胞内 电生理和光学测量，同时前所未有的 组织的光学透明度提供了极好的可见性 显微荧光技术。突触前神经元的可及性 终端将，特别是，用于调查这一作用， 结构，它的受体和假定的逆行信使， LTP的诱导和维持。 本研究旨在利用七鳃鳗中枢神经系统研究LTP的细胞方面 详细该制剂具有明显的优势， 调查突触前轴突和终末很大， 直接用贴片移液管或微电极记录。邮报- 突触神经元非常大（高达400微摩尔）， 稳定记录数小时。此外，细胞在其中的组织 位于光学清晰，提供了极好的机会， 成像和完整制剂内笼状化合物的光释放。 实验将使用微电极或全细胞贴片进行 来自突触的突触前和突触后两侧的记录。二 参与诱导和维持LTP的信使途径将被 通过Ca 2 +-的电生理记录和成像研究 轴突和突触后索马中的敏感染料。细胞内途径 将通过精确释放光可释放的 笼状化合物（如笼状核苷酸和Ca 2+）在精确定义 细胞间室这将通过结合微 将药剂注射到特定的细胞结构中， 使用共聚焦显微镜对已知细胞区室进行UV辐射 扫描仪酶抑制剂的微量注射也将用于 中断被认为参与LTP的途径（例如CaM激酶II， 蛋白激酶C，鸟苷酸环化酶）。

Understanding the mechanisms of learning and memory is a fundamental problem in neurobiology and cellular modifications of synaptic transmission have been implicated as an underlying substrate of learning. Fast synaptic transmission in the vertebrate central nervous system (CNS) is mediated largely by the release of amino acids. This transmission is subject to many modifying influences, including long term potentiation (LTP). LTP is defined as an increase in synaptic efficacy lasting for hours or longer, initiated by a brief period of high frequency stimulation (tetanus) to the synapse. This phenomenon is widespread at glutaminergic synapses in the vertebrate brain including the lamprey rhombencephalon. This from of LTP shares much in common with that seen in the mammalian hippocampus, including the role of glutamate receptor and a post-synaptic calcium flux. For the study of the cellular aspects of LTP the lamprey preparation offers distinct advantages. The large size of lamprey pre- synaptic terminals makes them available to direct intracellular electrophysiological and optical measurement, whilst the unprecedented optical clarity of the tissue affords excellent visibility for in vitro microfluorimetric techniques. The accessibility of the presynaptic terminal will, in particular, be used to investigate the role of this structure, its receptors and putative retrograde messengers in the induction and maintenance of LTP. It is intended to utilize the lamprey CNS to study cellular aspects of LTP in detail. This preparation has distinct advantages for this investigation. Presynaptic axons and terminals are large and may be directly recorded with patch pipettes or microelectrodes. The post- synaptic neurones are very large (up to 400 micromoles) and may be recorded stably for many hours. Additionally the tissue in which the cells are located is optically clear, providing excellent opportunities for imaging and photo-release of caged compounds within an intact preparation. Experiments will be performed using microelectrode or whole-cell patch recordings from both pre- and post-synaptic sides of the synapse. Second messenger pathways involved in induction and maintenance of LTP will be investigated by electrophysiological recording and imaging of Ca2+- sensitive dyes in axons and post-synaptic soma. Intracellular pathways will be experimentally manipulated by precise release of photoreleasable caged compounds (eg caged nucleotides and Ca2+) in precisely defined cellular compartments. This will be achieved by a combination of micro injection of agents into particular cellular structures and targeting of uv radiation to known cellular compartments using a confocal microscope scanner. Micro injection of enzyme inhibitors will also be used to interrupt pathways believed to be involved in LTP (eg CaM kinase II, protein kinase C, guanylate cyclase).