Mechanistic studies of 2-AG inactivation inhibitors as antidepressants

描述(由申请者提供)：抑郁症是一种使人虚弱并危及生命的疾病，影响着全球数百万人。临床上可用的抗抑郁药具有相同的核心机制，即增强单胺类药物在大脑中的传递。这种疾病的高患病率和目前治疗效果有限的情况表明，为抑郁症的治疗寻找新的治疗靶点的重要性和紧迫性。过去十年的临床和实验室观察表明，内源性大麻素(ECB)系统是抑郁症药物治疗的一个有前途的靶点。在治疗肥胖症的临床试验中，CB1大麻受体拮抗剂利莫那班会增加焦虑和抑郁的发生率，而大麻改善人类的情绪，CB1激动剂在抑郁的动物模型中产生抗抑郁药物样的作用。ECB失活的抑制剂以时间和空间特异性的方式放大内源性ECB的活性，作为治疗药物应该优于直接的CB1受体激动剂。ECB配体2-花生四烯基甘油(2-AG)被单酰甘油脂肪酶(MAGL)和丝氨酸水解酶α-β-水解酶结构域6和12(ABHD6/12)灭活。然而，目前尚不清楚抑制MAGL或ABHD6/12是否在抑郁症动物模型中产生抗抑郁作用。随着最近合成了选择性和有效的MAGL抑制剂JZL184和ABHD6抑制剂WWL123，解决这一重要问题成为可能。采用慢性轻度不可预测应激(CUS)作为抑郁症的动物模型，我们验证了2-AG信号在抑郁症中受损的假说，用MAGL或ABHD6抑制剂阻断2-AG失活可通过挽救2-AG信号的缺陷而产生抗抑郁药样作用。我们将通过两个特定的目标来检验这一假说：(1)在CUS抑郁症模型中检验2-AG信号受损的假说；(2)检验MAGL或ABHD6阻断通过挽救CUS引起的2-AG信号受损而产生抗抑郁药样作用的假说。在第一个目标下，我们将记录2-AG介导的电生理反应，以询问CUS抑郁症模型中海马区2-AG信号的进行状态。在第二个目标下，我们将检查体内慢性或亚慢性给药JZL184或WWL123是否通过修复CUS诱导的ECB信号缺陷而产生抗抑郁药样作用。我们还将检查MAGL基因敲除小鼠是否表现出抗抑郁药样的表型。这项研究的完成将有助于确定和验证抑郁症药物治疗的新靶点，并将提供对情绪调节机制和抑郁症病因的更好理解。 公共卫生相关性：这项拟议的研究调查了内源性大麻素失活抑制剂在抑郁症动物模型中的抗抑郁作用。该项目的完成将为开发和测试抑郁症的药物干预治疗策略提供机械和实践两个层面的知识。

DESCRIPTION (provided by applicant): Depression is a debilitating and life-threatening disease that affects millions of people worldwide. The clinically available antidepressants share the same core mechanisms of enhancing monoamine transmission in the brain. The high prevalence of the disease and limited effectiveness of current treatments indicate the importance and urgency to find novel therapeutic targets for the treatment of depression. Clinical and laboratory observations over the last decade indicate that the endocannabinoid (eCB) system represents a promising target for the pharmacotherapy of depression. The CB1 cannabinoid receptor antagonist rimonabant increases the incidence of anxiety and depression in clinical trials for the treatment of obesity, whereas cannabis improves mood in humans and CB1 agonists produce antidepressant-like effects in animal models of depression. Inhibitors of eCB inactivation amplify endogenous eCB activity in a temporal- and spatial-specific manner and should be superior to direct CB1 receptor agonists as therapeutic agents. The eCB ligand 2- arachidonoylglycerol (2-AG) is inactivated by monoacylglycerol lipase (MAGL) and serine hydrolase alpha- beta-hydrolase domain 6 and 12 (ABHD6/12). However, it remains unknown whether inhibition of MAGL or ABHD6/12 produces antidepressant effects in animal models of depression. Addressing this important question became possible now with the recent synthesis of selective and potent MAGL inhibitor JZL184 and ABHD6 inhibitor WWL123. Using chronic mild unpredictable stress (CUS) as an animal model for depression, we test the hypothesis that the 2-AG signaling is impaired in depression and the blockade of 2-AG inactivation with MAGL or ABHD6 inhibitors produces antidepressant-like effects by rescuing the deficiency in 2-AG signaling. We will test this hypothesis through two specific aims: (1) Test the hypothesis that 2-AG signaling is impaired in CUS model of depression; and (2) Test the hypothesis that MAGL or ABHD6 blockade produces antidepressant-like effects by rescuing CUS-induced impairment of 2-AG signaling. Under the first Aim, we will record 2-AG-mediated electrophysiological responses to interrogate ongoing status of 2-AG signaling in the hippocampus in a CUS model of depression. Under the second aim, we will examine whether in vivo chronic or subchronic administration of JZL184 or WWL123 produces antidepressant-like effects by rescuing CUS- induced deficiency in eCB signaling. We will also examine whether MAGL knockout mice exhibit antidepressant-like phenotypes. Completion of this investigation will lead to the identification and validation of new therapeutic targets for pharmacotherapy of depression and will provide an improved understanding of the mechanisms of mood regulation and the etiology of depression. PUBLIC HEALTH RELEVANCE: The proposed research investigates the antidepressant effects of inhibitors of endocannabinoid inactivation in an animal model of depression. Completion of this project will contribute knowledge at both mechanistic and practical levels for the development and testing of therapeutic strategies for pharmacological intervention of depression.