HALLUCINOGEN EFFECTS IN 5HT2A RECEPTOR MUTANT MICE

5-羟色胺/2 A受体被认为是迷幻剂对人类产生拟精神作用的主要媒介。在PPG的这一部分，我们将利用转基因小鼠研究5-羟色胺/2A受体在致幻剂行为行为中的作用。5-羟色胺/2 A受体基因零突变的小鼠对5-羟色胺能迷幻剂的许多行为和生理效应没有反应。为了更好地确定5-羟色胺/2A受体在致幻剂的特定行为行为中的作用，我们将使用更广泛的致幻和非致幻激动剂在野生型和5-羟色胺/2A基因敲除小鼠上进行额外的实验(头部抽动反应、强制探索新环境和药物识别)。为了研究致幻剂与人类5-HT/2A受体相互作用的特定方面，我们将创造表达人类野生型或四种不同突变版本的人类5-HT/2A受体的“敲入”小鼠品系，以取代内源性受体。在该PPG的其他组件中设计和评估这些突变，测试致幻剂与人5-HT/2A受体相互作用的特定方面：(1)激动剂定位对内在活性的影响；(2)受体构象和G蛋白偶联的影响；(3)破坏非活性形式受体的稳定的影响；以及最终，(4)减少受体脱敏和内化对对迷幻剂影响的耐受性的影响-使用新的结构。我们将创造这些敲入小鼠，并检查它们对致幻和非致幻激动剂的行为反应。这些敲入小鼠还将用于PPG其他成分的体外实验，以表征突变对激动剂介导的信号转导和基因表达的体内影响。这些人源化的5-HT/2A敲入小鼠的创建和表征将使这种PPG的三个组成部分通过计划中的合作实现更好地了解迷幻剂与人类5-HT/2A受体相互作用的分子、细胞和行为方面，这些相互作用是其影响的基础。

The 5-HT/2A receptor is thought to be the main mediator of the psychotomimetic effects of hallucinogens in humans. In this component of the PPG, we will study the role of 5-HT/2A receptor in the behavioral actions of hallucinogens using genetically altered mice. Mice with a null mutation of the 5-HT/2A receptor gene are unresponsive to many of the behavioral and physiologic effects of serotonergic hallucinogens. To better define the roles of the 5-HT/2A receptor in specific behavioral actions of hallucinogens, we will perform additional experiments (head twitch response, forced exploration of a novel environment an drug discrimination) on the wild-type and 5-HT/2A knockout mice using a broader range of hallucinogenic and non-hallucinogenic agonists. In order to study specific aspects of the interactions of hallucinogens with the human 5-HT/2A receptor, we will create strains of "knock-in" mice expressing the human wild-type or four different mutated versions of the human 5-HT/2A receptor in place of the endogenous receptor. Designed and evaluated in the other components of this PPG, these mutations test specific aspects of the interactions of hallucinogens with the human 5- HT/2A receptor: (1) the effect of agonist positioning on intrinsic positioning on intrinsic activity; (2) the effect of receptor conformation and G-protein coupling; (3) the effect of destabilizing the inactive form of the receptor; and eventually, (4) the effect of reducing receptor desensitization and internalization on the development of tolerance to the effects of hallucinogens-using a new construct. We will create these knock-in mice and examine their behavioral response to hallucinogenic and non-hallucinogenic agonists. These knock-in mice will also be used in ex-vivo experiments in the other components of this PPG to characterize the in vivo effects of the mutations on agonist-mediated signal transduction and gene expression. The creation and characterization of these humanized 5-HT/2A knock-in mice will allow the three components of this PPG to achieve through the planned collaborations a better understanding of the molecular, cellular, and behavioral aspects of hallucinogen interactions with the human 5-HT/2A receptor that underlie their effects.