Role of calcium-dependent mechanisms in nicotine's tolerance and effects

描述（由申请人提供）：本提案的主要目的是阐明尼古丁的影响和依赖的钙依赖机制。神经元烟碱受体的Ca2+通透性提示钙介导的信号级联反应的重要作用。Ca2+依赖性激酶，特别是Ca2+钙调素依赖性蛋白激酶II (CaMKII)，已知在神经元可塑性中起重要作用，因此是促进神经元适应导致尼古丁依赖的有吸引力的候选者。本提案的重点是验证CaMKII通过腹侧被盖区（VTA）的a4b2* nAChRs亚型激活在尼古丁奖励效应中起重要作用的假设。在这个项目中，我们将首先评估CaMKII激活在VTA对尼古丁的急性反应中的潜在作用。为了验证a4b2* nAChR亚型介导尼古丁对VTA中CaMKII活性影响的假设，后续研究将涉及使用各种尼古丁拮抗剂和不同的nAChR转基因小鼠。利用l型钙通道（LCC）和NMDA受体的特异性抑制剂，我们将确定谷氨酸和LCC传递是否有助于尼古丁诱导的CaMKII活性。最后，使用CaMKII抑制剂和CaMKII KO小鼠，我们将确定CREB是否是尼古丁在VTA中诱导CaMKII激活的靶点之一。接下来，我们将讨论尼古丁依赖可能涉及CaMKII信号系统使用小鼠条件位置偏好（CPP）的适应的假设，这是一种尼古丁奖励的动物模型。将采用多种方法。我们将首先通过测量在调节尼古丁位置偏好的不同阶段中VTA和海马体中CaMKII活性和水平的变化来扩展我们的初步发现。此外，我们将研究CaMKII在VTA和海马中的激活是否介导尼古丁诱导的CPP表达，方法是在CPP训练小鼠的VTA和海马内给予CaMKII抑制剂。此外，补充行为研究将利用CaMKII敲除小鼠在尼古丁诱导的CPP。在CaMKII通路的急性研究（Aim 1）中产生的结果将在CPP模型中进一步研究。拟议的研究将有助于阐明尼古丁依赖的分子基础，以及在短期和长期暴露于这种药物滥用后发生的Ca2+依赖的神经适应过程。

DESCRIPTION (provided by applicant): The broad objective of this proposal is to elucidate the calcium-dependent mechanisms of nicotine's effects and dependence. The Ca2+permeability of neuronal nicotinic receptors suggests an important role for calcium-mediated signaling cascades. Ca2+dependent kinases, in particular Ca2+calmodulin-dependent protein kinase II (CaMKII), are known to play an important role in neuronal plasticity and are therefore attractive candidates for contributing to neuronal adaptation leading to nicotine dependence. The focus of this proposal is to test the hypothesis that CaMKII activation through a4b2* nAChRs subtypes in the ventral tegmental Area (VTA) plays an important role in the rewarding effects of nicotine. In this project we will first assess the potential role of CaMKII activation in the acute response to nicotine in the VTA. Subsequent studies involving the use of various nicotinic antagonists and different nAChRs transgenic mice will be carried out in order to test the hypothesis that a4b2* nAChR subtypes mediate nicotine's effects on CaMKII activity in the VTA. Using specific inhibitors of L-type calcium channels (LCC) and NMDA receptors, we will then determine whether glutamate and LCC transmissions contribute to nicotine-induced CaMKII activity. Finally, using CaMKII inhibitors and CaMKII KO mice, we will determine if CREB is one the targets of CaMKII activation induced by nicotine in the VTA. We will next address the hypothesis that nicotine dependence may involve an adaptation of the CaMKII signaling system using conditioned place preference (CPP) in mice, an animal model of nicotine reward. Multiple approaches will be employed. We will first extend our preliminary findings by measuring changes of CaMKII activity and levels in the VTA and hippocampus during the various stages of conditioning nicotine place preference. Additionally, we will examine if CaMKII activation in the VTA and hippocampus mediate the expression of nicotine-induced CPP by performing an intra-VTA and intra-hippocampus administration of CaMKII inhibitors in CPP trained mice. Furthermore, complementary behavioral studies will utilize CaMKII Knock-out mice in nicotine-induced CPP. Results generated from acute studies (Aim 1) on CaMKII pathway will be further investigated in the CPP model. The proposed studies will help elucidate the molecular basis of nicotine dependence as well as the Ca2+ dependent neuroadaptation processes that occurs after short-and long-term exposure to this drug of abuse.