Endocannabinoid biosynthesis and inactivation, from simple to complex

Cannabinoid receptors, the primary molecular targets of the endocannabinoid system, are activated by specific bioactive lipids termed 'endocannabinoids'. These lipid transmitters are synthesized from cell membrane phospholipids through multiple pathways and are inactivated by enzymatic hydrolysis, and their levels are the major parameter driving the endocannabinoid system activity. An in-depth understanding of their metabolic pathways is essential to unravel the endocannabinoid system's role in physiological and pathological situations and to devise new therapeutic strategies based on the endocannabinoid system. Major advances both in the characterization of anandamide's and 2-arachidonoylglycerol's biosynthesis and inactivation pathways and in the discovery of pharmacological tools used to interfere with their metabolism have been made and are discussed in this review.