Endocannabinoid signaling is implicated in an array of psychopathologies ranging from anxiety to psychosis and addiction. In recent years, radiotracers targeting the endocannabinoid system have been used in positron emission tomography (PET) studies to determine whether individuals with psychiatric disorders display altered endocannabinoid signaling. We comprehensively reviewed PET studies examining differences in endocannabinoid signaling between individuals with psychiatric illness and healthy controls. Published studies evaluated individuals with five psychiatric disorders: cannabis use disorder, alcohol use disorder, schizophrenia, post-traumatic stress disorder, and eating disorders. Most studies employed radiotracers targeting cannabinoid receptor 1 (CB1). Cannabis users consistently demonstrated decreased CB1 binding compared to controls, with normalization following short periods of abstinence. Findings in those with alcohol use disorder and schizophrenia were less consistent, with some studies demonstrating increased CB1 binding and others demonstrating decreased CB1 binding. Evidence of aberrant CB1 binding was also found in individuals with anorexia nervosa and post-traumatic stress disorder, but limited data have been published to date. Thus, existing evidence suggests that alterations in endocannabinoid signaling are present in a range of psychiatric disorders. Although recent efforts have largely focused on evaluating CB1 binding, the synthesis of new radiotracers targeting enzymes involved in endocannabinoid degradation, such as fatty acid amide hydrolase, will allow for other facets of endocannabinoid signaling to be evaluated in future studies.

中文翻译：

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精神疾病中的内源性大麻素信号传导：正电子发射断层扫描研究综述。

内源性大麻素信号传导与一系列精神病理学有关，从焦虑到精神病和成瘾。近年来，针对内源性大麻素系统的放射性示踪剂已用于正电子发射断层扫描（PET）研究，以确定患有精神疾病的个体是否表现出内源性大麻素信号改变。我们全面回顾了 PET 研究，这些研究检查了精神疾病患者和健康对照者之间内源性大麻素信号传导的差异。已发表的研究评估了患有五种精神疾病的个体：大麻使用障碍、酒精使用障碍、精神分裂症、创伤后应激障碍和饮食失调。大多数研究采用针对大麻素受体 1 (CB1) 的放射性示踪剂。与对照组相比，大麻使用者始终表现出 CB1 结合减少，并在短期戒断后恢复正常。在酒精使用障碍和精神分裂症患者中的研究结果不太一致，一些研究表明 CB1 结合增加，而另一些研究表明 CB1 结合减少。在患有神经性厌食症和创伤后应激障碍的个体中也发现了异常 CB1 结合的证据，但迄今为止发表的数据有限。因此，现有证据表明内源性大麻素信号传导的改变存在于一系列精神疾病中。尽管最近的努力主要集中在评估 CB1 结合上，但针对参与内源性大麻素降解的酶（例如脂肪酸酰胺水解酶）的新型放射性示踪剂的合成，将允许在未来的研究中评估内源性大麻素信号传导的其他方面。