The endocannabinoid system (ECS) is involved in a wide range of biological functions and comprises cannabinoid receptors and enzymes responsible for endocannabinoid synthesis and degradation. Over the past 2 decades, significant advances toward developing drugs and positron emission tomography (PET) tracers targeting different components of the ECS have been made. Herein, we summarized the recent development of PET tracers for imaging cannabinoid receptors 1 (CB1R) and 2 (CB2R) as well as the key enzymes monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), particularly focusing on PET neuroimaging applications. State-of-the-art PET tracers for the ECS will be reviewed including their chemical design, pharmacological properties, radiolabeling, as well as preclinical and human PET imaging. In addition, this review addresses the current challenges for ECS PET biomarker development and highlights the important role of PET ligands to study disease pathophysiology as well as to facilitate drug discovery.

中文翻译：

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内源性大麻素系统的正电子发射断层扫描成像：放射性示踪剂开发的机遇和挑战

内源性大麻素系统 (ECS) 涉及广泛的生物学功能，包括大麻素受体和负责内源性大麻素合成和降解的酶。在过去的 20 年中，在开发针对 ECS 不同成分的药物和正电子发射断层扫描 (PET) 示踪剂方面取得了重大进展。在此，我们总结了用于成像大麻素受体 1 (CB1R) 和 2 (CB2R) 以及关键酶单酰基甘油脂肪酶 (MAGL) 和脂肪酸酰胺水解酶 (FAAH) 的 PET 示踪剂的最新发展，特别关注 PET 神经成像应用。将审查用于 ECS 的最先进的 PET 示踪剂，包括其化学设计、药理特性、放射性标记以及临床前和人体 PET 成像。此外，