Mechanisms Underlying TAAR1-induced Wakefulness and REM Sleep Suppression

项目总结 微量胺相关受体1(TAAR1)是一种G蛋白偶联受体，参与调节 多巴胺能、5-羟色胺能和谷氨酸能活动。TAAR1激动剂有抗焦虑、抗抑郁和 啮齿动物和非人类灵长类动物的抗精神病药样特性；TAAR1激动剂正在进行临床试验 精神分裂症和帕金森氏症精神病。我们先前已经证明，TAAR1激动剂是唤醒- 在小鼠、大鼠和最近的非人类灵长类动物中，促进是睡眠/觉醒表型的特征 Taar1基因敲除(KO)和过度表达(OE)小鼠，并评价TAAR1激动剂对 野生型(WT)、KO和OE小鼠的睡眠/觉醒。我们还表明，两种不同的TAAR1激动剂抑制 快速眼动睡眠和减少发作性睡病小鼠的猝倒，正是 发作性睡病治疗。在建立了TAAR1激动剂作为治疗发作性睡病的潜在新疗法之后，我们 现在将研究潜在的体内神经生物学。在Taar1-LacZ小鼠中，我们将确定TAAR1 在单胺、谷氨酸或其他类型的细胞中表达，并使用RNAScope技术 测定WT和KO小鼠和大鼠内源性Taar1mRNA的表达。由于TAAR1为负 在体外调节多巴胺(DA)能神经元的活动，我们将检验TAAR1部分激动性的假设 通过调节DA唤醒系统来促进清醒。为了解决这一假设，我们将评估 用体内钙离子研究DAT-res-Cre小鼠腹侧被盖区和中缝背核神经元的活动 显微内窥镜检查，并确定用DAD1和D2受体拮抗剂预处理是否减弱 TAAR1介导的觉醒促进作用。由于5-羟色胺能神经元是觉醒活动和REM非活动的，并且TAAR1 在体外负向调节5-羟色胺能神经元的活性，我们还将检验TAAR1部分 激动感通过调节5-羟色胺能唤醒系统促进觉醒。我们将确定是否 利用体内钙离子显微内窥镜观察TAAR1部分激动剂调节DRN 5-羟色胺能神经元的活性 并评估阻断5-羟色胺能信号是否减弱觉醒促进作用 TAAR1部分激动剂。我们已经发现，TAAR1缺失会提高高频伽马脑电活动， 提示TAAR1对皮质功能有调节作用。确定TAAR1介导的血管紧张素转换酶是否升高 伽马活动在物种间是保守的，并且是TAAR1特有的，我们将研究基础睡眠/觉醒 对Taar1 KO和OE大鼠以及Taar2-9 KO小鼠进行生理学和定量脑电分析。一起， 这些目标将开始建立作为TAAR1疗效基础的神经回路和机制 激动剂。

PROJECT SUMMARY Trace amine-associated receptor 1 (TAAR1) is a G protein-coupled receptor involved in the regulation of dopaminergic, serotonergic and glutamatergic activity. TAAR1 agonists have anxiolytic, antidepressant-, and antipsychotic-like properties in both rodent and non-human primates; TAAR1 agonists are in clinical trials for schizophrenia and Parkinson’s disease psychosis. We have previously shown that TAAR1 agonists are wake- promoting in mice, rats and, most recently, non-human primates, characterized the sleep/wake phenotype of Taar1 knockout (KO) and overexpressing (OE) mice, and evaluated the effects of TAAR1 agonists on sleep/wake in wildtype (WT), KO and OE mice. We also showed that two different TAAR1 agonists suppressed REM sleep and reduced cataplexy in mouse models of narcolepsy, precisely the properties desirable in a narcolepsy therapeutic. Having established TAAR1 agonists as potential novel treatments for narcolepsy, we will now investigate the underlying in vivo neurobiology. In Taar1-LacZ mice, we will determine whether TAAR1 is expressed in monoaminergic, glutamatergic or other cell types and use the RNAscope technology to determine endogenous Taar1 mRNA expression in WT and KO mice and rats. Since TAAR1 negatively regulates dopaminergic (DA) neuronal activity in vitro, we will test the hypothesis that TAAR1 partial agonism promotes wakefulness by modulating DA arousal systems. To address this hypothesis, we will assess neuronal activity in the ventral tegmental area and dorsal raphe nuclei of DAT-ires-Cre mice using in vivo Ca2+ microendoscopy, and determine whether pretreatment with DA D1- and D2-receptor antagonists attenuates TAAR1-mediated wake-promotion. Since serotonergic neurons are wake-active and REM-inactive and TAAR1 negatively regulates serotonergic neuronal activity in vitro, we will also test the hypothesis that TAAR1 partial agonism promotes wakefulness by modulating serotonergic arousal systems. We will determine whether TAAR1 partial agonists modulate the activity of DRN serotonergic neurons using in vivo Ca2+ microendoscopy in Fev-Cre mice and assess whether blockade of serotonergic signaling attenuates the wake-promoting effects of TAAR1 partial agonists. We have found that TAAR1 deletion elevates high-frequency gamma EEG activity, suggesting that TAAR1 modulates cortical function. To determine whether TAAR1-mediated elevation of gamma activity is conserved across species and specific to TAAR1, we will investigate basal sleep/wake physiology and conduct quantitative EEG analyses in Taar1 KO and OE rats and Taar2-9 KO mice. Together, these Aims will begin to establish the neural circuitry and mechanisms that underlie the efficacy of TAAR1 agonists.