The Septohippocampal System: Regulation by Neurotrophins

描述(由申请人提供)：细胞和亚细胞机制的可塑性变化是神经行为表现和神经系统功能的关键决定因素。本研究拟探讨神经生长因子对隔-海马(S-H)系统的调节作用。中心假说是，小鼠海马内神经生长因子功能的增强在短期内增强了隔区胆碱能神经元的活性，从长期来看，导致内侧隔/斜角带核(MS/NDB)和海马区的突触重组，从而导致沿着S-H系统的神经传递。为了验证这一假设，我们将使用转基因小鼠作为实验模型，转基因小鼠拥有海马区内定向获得的NGF功能。这些实验结合了膜片钳记录、免疫组织化学和PCR扩增免疫反应检测(PADI)，分为三个特定的目标。具体目标1将检验这样一种假设，即GABA能MS/NDB神经元受到MS/nDNB胆碱能活动维持的毒扁豆碱张力的调节。《特定目的2》将验证一种假设，即海马区定向激活和增加神经生长因子的表达会导致MS/nDNB神经元的特性发生变化，这种变化与增强的毒碱基调一致，从而导致S-H通路的活动。特定目标3将使用隔区-海马区共培养系统来测试NGF的靶向激活是时间和活动依赖的假设。在检验这些假设时，固有的概念是特定的细胞和分子变化可以与NGF激活相关。因此，除了电生理实验外，候选蛋白质还将通过激光捕获显微切割分离的单个神经元中基于聚合酶链式反应的蛋白质检测技术进行分析。总体而言，这个项目将有助于我们理解神经生长因子诱导神经系统可塑性的细胞和分子基础，并探索靶向基因转移作为一种潜在的治疗策略的价值，以改善各种神经退行性疾病中认知功能障碍的衰弱后果。

DESCRIPTION (provided by applicant): Plastic changes in cellular and subcellular mechanisms are critical determinants of neurobehavioral manifestations; of nervous system function. We propose to investigate the regulation of the septohipppocampal (S-H) system by nerve growth factor (NGF). The central hypothesis is that an intrahippocampal gain of NGF function in mice enhances activity of septal cholinergic neurons in the short term and, in the long term, leads to synantic reorganization in both the medical septum/nucleus of Diagonal Band (MS/nDB) and hippocampus and, thereby neurotransmission along the S-H system. To test this hypothesis, we will use as experimental model transgenic mice harboring a targeted intrahippocampal gain of NGF function. The experiments, incorporating patch clamp recording, immunohistochemistry and PCR-Amplified Detection of Immunoreactivity (PADI), are organized into three specific aims. Specific Aim 1 will test the hypothesis that GABAergic MS/nDB neurons are under regulation of a muscarinic tone that is maintained by cholinergic activity in the MS/nDNB. Specific Aim 2 will test the hypothesis that a targeted activation and increase in the expression of NGF in the hippocampus leads to changes in the properties of MS/nDNB neurons that are consistent with an augmented muscarinic tone and thus activity alongthe S-H pathway. Specific Aim 3 will employ a septohippocampal coculture system to test the hypothesis that the targeted activation of NGF is time- and activity-dependent. Inherent in testing these hypothesis is the notion that specific cellular and molecular changes can be correlated with NGF activation. Thus, in addition to the electrophysiological experiments, candidate proteins will be analyzed by a PCR-based protein detection technique in single neurons isolated by laser capture microdissection. Overall, this project will contribute to our understanding of the cellular and molecular bases underlying NGF-induced plasticity in the nervous system and explore the value of targeted gene transfer as a potential therapeutic strategy to ameliorate the debilitating consequences of cognitive dysfunction as seen in a variety of neurodegenerative conditions.