CELLULAR RESPONSES TO HALLUCINOGENS

滥用的致幻药物是5-羟色胺5-HT2A受体的部分激动剂。调节其致幻潜力的分子机制尚不清楚。利用我们之前在IRPG中的跨学科工作发展起来的关于迷幻剂与H-HT/2A受体相互作用的理解，我们建议研究作用于5-HT2A受体的致幻和非致幻5-羟色胺能激动剂所诱导的特殊构象效应。与受体结合的激动剂在特定的相对构象分布中稳定蛋白质。每种构象状态都倾向于与特定的G蛋白相互作用，诱导第二信使反应和内源基因的激活，并与调节蛋白相互作用，导致磷酸化、内化和脱敏。这些下游效应将被分析为对由特定激动剂稳定的构象阶段的反映。将研究致幻潜力不同的全部和部分5-羟色胺/2A激动剂，并调查观察到的反应不同的基础。H-HT2A受体的突变改变了相对激动剂的位置和疗效、相对G蛋白激活和非活动阶段的稳定性，并将确定它们对不同迷幻剂和非迷幻剂在细胞系中引发的反应的影响。为了分析细胞系和活体神经元中的细胞反应，我们将分析细胞信号的内在报告(IRC)，它表现出对信号转导激活的快速反应。IRC对致幻剂和非致幻剂的反应将在表达人类野生型和突变型受体的敲入小鼠的皮质神经元中进行测量，以取代内源性受体。这些研究将为细胞对5-羟色胺/2A受体产生的致幻化学物质的反应提供分子基础，并可能促进新的治疗方式的开发。

Hallucinogenic drugs of abuse are partial agonists at the serotonin 5- HT2A receptor. The molecular mechanisms mediating their hallucinogenic potential are not known. Utilizing the understanding about hallucinogen interactions with the H-HT/2A receptor that we have developed from our previous inter-disciplinary work in an IRPG, we propose to study the specific conformational effects induced by hallucinogenic and non-hallucinogenic serotonergic agonists acting at the 5-HT2A receptor. Agonist binding to a receptor stabilizes the protein in a particular relative distribution of conformations. Each conformational state has a propensity to interact with specific G-proteins, inducing second messenger responses and activation of endogenous genes, and with regulatory proteins, leading to phosphorylation, internalization, and desensitization. These downstream effects will be assayed as reflections on the conformational stages stabilized by a particular agonist. Full and partial 5-HT/2A agonists that differ in their hallucinogenic potential will be studied and the basis for differences in the responses observed will be investigated. Mutations of the H-HT2A receptor that modify relative agonist positioning and efficacy, relative G-protein activation, and stability of the inactive stage have been identified and their effects on the responses elicited in cell lines by different hallucinogens and non- hallucinogens will be determined. In order to assay cellular responses both in cell lines and in neurons in vivo, we will assay intrinsic reporters of cellular signaling (IRC) that manifest rapid alterations in response to signal transduction activation. IRC responses to hallucinogens and non- hallucinogens will be measured in cortical neurons in knock-in mice expressing the human wild-type and mutant receptors in place of the endogenous receptor. These studies will provide insight into the molecular basis for the cellular responses to hallucinogenic chemicals elicited at the 5-HT/2A receptor and may facilitate the development of new therapeutic modalities.