Roles and mechanisms of neurotensin in learning and memory

描述（申请人提供）：神经紧张素（NT）是一种广泛分布于包括内嗅皮质（EC）在内的中枢神经系统的三肽，对学习和记忆至关重要，在阿尔茨海默病（AD）中发生最早的病理改变。虽然在EC中检测到高密度的NT受体，但NT在学习记忆和AD中的作用尚未确定。阿尔茨海默病的特征是认知能力的进行性恶化，约有530万美国人患有此病。目前可用于治疗AD的药物包括胆碱酯酶抑制剂和部分NMDA受体拮抗剂美金刚仅在有限的时间内对一部分患者有效。因此，识别和表征认知缺陷可以改善的其他机制仍然是阿尔茨海默病治疗的重要途径。本研究拟进一步研究NT在促进空间记忆中的作用及其机制，并在AD小鼠模型中验证NT受体激动剂治疗AD的可能性。我们有大量的初步数据表明，NT在EC中诱导神经元兴奋性的长期兴奋（LTE）。在巴恩斯迷宫实验中，我们还发现脑皮层微注射NT有助于空间学习和记忆。本项目的目的是通过验证NT通过NTS1/PLC/ pkc依赖性抑制TREK-2通道诱导神经元兴奋性LTE并促进空间学习和记忆的假设，确定所涉及的细胞和分子机制。目的1将确定脑皮层内nt诱导的神经元兴奋性LTE的机制。我们将确定PKC异构体、PKC在TREK-2通道中的磷酸化位点和PKC依赖的TREK-2通道磷酸化在体内nt介导的EC LTE中的作用。目的2将通过药理学方法和敲除小鼠验证NT通过激活PLC和PKC通路从而抑制EC中TREK-2通道增强空间学习和记忆的假设，从而确定NT促进空间学习和记忆的机制。目的3将确定NT和PD149163（一种可穿透血脑屏障的NTS1小分子激动剂）对AD小鼠APP/PS1模型空间学习和记忆的影响。我们期望确定NT促进空间学习和记忆的细胞和分子机制，并确定在AD小鼠模型中使用NTS1激动剂治疗AD的新方法。

DESCRIPTION (provided by applicant): Neurotensin (NT) is a tridecapeptide widely distributed in the CNS including the entorhinal cortex (EC) which is crucial for learning and memory and undergoes the earliest pathological alterations in Alzheimer's Disease (AD). Whereas high density of NT receptors has been detected in the EC, the roles of NT in learning and memory and in AD have not been determined. AD is characterized by progressive deterioration of cognitive performance and afflicts ~5.3 million Americans. The current drugs available for the treatment of AD including the cholinesterase inhibitors and the partial NMDA receptor antagonist memantine only benefit a subset of patients for a limited period. Therefore, identifying and characterizing additional mechanisms through which cognitive deficiency can be improved still represent an important approach for AD therapy. We propose to study the roles and the underlying mechanisms of NT in facilitation of spatial memory in the EC and then test the possibility of using NT receptor agonists for AD therapy in AD mouse model. We have substantial preliminary data demonstrating that NT induced Long-Term Excitation (LTE) of neuronal excitability in the EC. We also demonstrated that microinjection of NT into the EC facilitated spatial learning and memory in Barnes Maze Test. The objective of this project is to determine the involved cellular and molecular mechanisms by testing the hypothesis that NT induces LTE of neuronal excitability and facilitates spatial learning and memory via NTS1/PLC/PKC-dependent inhibition of TREK-2 channels. Aim 1 will identify mechanisms underlying NT-induced LTE of neuronal excitability in the EC. We will identify the roles of PKC isoforms, PKC phosphorylation sites in TREK-2 channels and PKC- dependent phosphorylation of TREK-2 channels in vivo in NT-mediated LTE in the EC. Aim 2 will determine the mechanisms whereby NT facilitates spatial learning and memory by testing the hypothesis that NT augments spatial learning and memory via activation of PLC and PKC pathway resulting in inhibition of TREK-2 channels in the EC by using both pharmacological approach and knockout mice. Aim 3 will identify effects of NT and PD149163, a small molecule NTS1 agonist that can penetrate the blood-brain barrier on spatial learning and memory in APP/PS1 mice, an AD mouse model. We expect to determine the cellular and molecular mechanisms whereby NT facilitates spatial learning and memory and identify a novel approach of using NTS1 agonists for AD therapy in AD mouse model.