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

描述（由申请方提供）：本提案的主要目的是阐明尼古丁作用和依赖性的钙依赖性机制。神经元烟碱受体的Ca2+渗透性表明钙介导的信号级联的重要作用。已知Ca2+依赖性激酶，特别是Ca2+钙调蛋白依赖性蛋白激酶II（CaMKII）在神经元可塑性中起重要作用，因此是有助于导致尼古丁依赖的神经元适应的有吸引力的候选者。该建议的重点是验证以下假设：通过腹侧被盖区（VTA）中的a4b2* nAChRs亚型激活CaMKII在尼古丁的奖励效应中起重要作用。在本项目中，我们将首先评估CaMKII激活在腹侧被盖区对尼古丁的急性反应中的潜在作用。将进行涉及使用各种烟碱拮抗剂和不同nAChR转基因小鼠的后续研究，以检验a4b2* nAChR亚型介导尼古丁对VTA中CaMKII活性的影响的假设。使用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传输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VTA中尼古丁诱导的CaMKII活化的靶点之一。接下来，我们将讨论尼古丁依赖可能涉及CaMKII信号传导系统的适应性的假设，在小鼠中使用条件性位置偏好（CPP），尼古丁奖励的动物模型。将采用多种方法。我们将首先扩展我们的初步研究结果，通过测量CaMKII活性和水平的变化，在VTA和海马在调节尼古丁位置偏好的各个阶段。此外，我们将通过在CPP训练的小鼠中进行VTA内和海马内施用CaMKII抑制剂来检查VTA和海马中的CaMKII活化是否介导尼古丁诱导的CPP的表达。此外，补充行为研究将在尼古丁诱导的CPP中利用CaMKII敲除小鼠。将在CPP模型中进一步研究CaMKII通路急性研究（目的1）产生的结果。拟议的研究将有助于阐明尼古丁依赖的分子基础，以及短期和长期暴露于这种滥用药物后发生的Ca2+依赖性神经适应过程。

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.