D. Melck, V. Di Marzo*, T. Bisogno, L. De Petrocellis and B.R. Martin Pages 721 - 744 ( 24 )
In agreement with the highly lipophilic nature of (-)-Δ-9-tetrahydrocannabinol, all the endogenous ligands of cannabinoid receptors identified so far are derivatives of long chain fatty acids. N- Arachidonoylethanolamine (anandamide) and some of its polyunsaturated congeners have been found in mammalian brain and shown to activate the CB1 and, with a lower efficacy, CB2 cannabinoid receptor subtypes. More recently, 2-arachidonoylglycerol (2-AG), a widespread intermediate in the metabolism of phosphoglycerides, diacylglycerols and triglycerides, was also found to activate the cannabinoid receptors. The capability of palmitoylethanolamide, an anti-inflammatory metabolite, to activate CB2-Iike receptors is still being debated. Here we review: 1) the metabolic pathways suggested so far to underlie the biosynthesis and inactivation of anandamide and 2-AG, and 2) the current knowledge of the chemical bases for the interactions of anandamide and 2-AG with proteins of the 'endogenous cannabinoid system' characterized so far, i.e. the CB1 and CB2 receptor subtypes, the membrane 'anandamide carrier', which facilitates anandamide diffusion into cells, and the enzyme 'fatty acid amide hydrolase', which catalyzes anandamide and, to a certain extent, 2-AG hydrolysis in vivo.