Regulation of Synaptic Plasticity in Hippocampus In Vivo

描述（由申请人提供）：作为学习和记忆基础的神经生物学事件可能包括已知有助于记忆的脑结构中突触强度的活动依赖性修饰。假设有助于记忆的使用依赖性突触修饰的例子是长时程增强（LTP）和长时程抑制（LTD）的突触传递在兴奋性突触在Zampus。海马LTP类似于海马LTP，在体内CA 1区持续数天。LTD的持久性表明，潜在的分子机制涉及改变基因表达，虽然一些表达的变化必须不同于参与LTP。拟议的工作解决了这个问题，通过检查的作用，丝氨酸/苏氨酸蛋白磷酸酶PP 1和PP 2A和细胞外信号调节激酶（ERK）级联LTD和LTP在CA 1区在体内。 在本实验室和其他实验室工作的基础上，我们拟进行以下研究：（1）确定PP 1或PP 2A是否与LTD过程中转录因子CREB的激活降低有关，并在LTD的持续性中发挥作用;（2）为了确定LTD是否需要从头转录和翻译，并且与ERK/Elk-l的增加相关，介导的基因表达而不是CREB介导的表达;和（3）描述ERK在LTD与LTP中CREB和Elk-1功能调节中的作用，并测试LTP期间CREB上磷酸酶作用的降低是否有助于LTP的持续。我们将结合体内电生理技术、酶活性测定、蛋白质印迹和免疫组织化学分析以及原位杂交来解决这些问题。总的来说，这些研究将阐明转录信号的负调控和正调控机制，以响应在成人体内海马可塑性诱导的突触激活，并将产生不同的信号事件之间的相互作用如何在双向突触可塑性的调节联合收割机的模型。这些研究的发现将为未来的工作提供基础，这些工作旨在将双向突触可塑性中涉及的信号事件与行为动物执行的不同类型记忆操作中涉及的信号事件联系起来。

DESCRIPTION (provided by applicant): The neurobiological events that underlie learning and memory likely include activity-dependent modification of synaptic strength in brain structures known to subserve memory. Examples of use-dependent synaptic modification hypothesized to contribute to memory are long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission at excitatory synapses in the hippozampus. Hippocampal LTD, similar to hippocampal LTP, is persistent, lasting for days in area CA1 in vivo. The persistence of LTD suggests that the underlying molecular mechanisms involve altered gene expression, although some of the changes in expression must differ from those involved in LTP. The proposed work addresses this issue by examining the role of the serine/threonine protein phosphatases PP1 and PP2A and that of the extracellular signal-regulated kinase (ERK) cascade in LTD and LTP in area CA1 in vivo. Motivated by previous work from our laboratory and work by others, we propose to pursue the following Specific Aims: (1) To determine whether PP1 or PP2A is responsible for decreased activation of the transcription factor CREB during LTD and plays a role in the persistence of LTD; (2) To determine whether LTD requires de novo transcription and translation and is associated with an increase in ERK/Elk-l-mediated gene expression but not in CREB-mediated expression; and (3) To delineate the role of ERK in the regulation of CREB and Elk-1 function in LTD vs. LTP, and test whether reduced phosphatase action on CREB during LTP contributes to the persistence of LTP. We will address these questions with a combination of in vivo electrophysiological techniques, enzyme activity assays, Western blot and immunohistochemical analyses, and in situ hybridization. Collectively, the studies will elucidate mechanisms of negative and positive regulation of transcriptional signals in response to plasticity-inducing synaptic activation in the adult in vivo hippocampus, and will yield models of how interactions among different signaling events combine in the regulation of bidirectional synaptic plasticity. The findings from these studies will provide the foundation for future work directed at relating signaling events involved in bidirectional synaptic plasticity to signaling events involved in different types of memory operations performed by behaving animals.