Functional Role of High-Affinity Anandamide Transport, as Revealed by Selective Inhibition

Abstract

Anandamide, an endogenous ligand for central cannabinoid receptors, is released from neurons on depolarization and rapidly inactivated. Anandamide inactivation is not completely understood, but it may occur by transport into cells or by enzymatic hydrolysis. The compound N -(4-hydroxyphenyl)arachidonylamide (AM404) was shown to inhibit high-affinity anandamide accumulation in rat neurons and astrocytes in vitro, an indication that this accumulation resulted from carrier-mediated transport. Although AM404 did not activate cannabinoid receptors or inhibit anandamide hydrolysis, it enhanced receptor-mediated anandamide responses in vitro and in vivo. The data indicate that carrier-mediated transport may be essential for termination of the biological effects of anandamide, and may represent a potential drug target.

Antinociceptive activity of the endogenous fatty acid amide, palmitylethanolamide

“…Moreover, in previous studies, we have shown that anandamide prevents thermal nociception and that this effect is also blocked by the cannabinoid CB antagonist 1 Ž . SR141716A Beltramo et al, 1997 . A plausible explanation for our findings is that anandamide and palmitylethanolamide exert their peripheral antinociceptive effects by interacting with different molecular and cellular targets.…”

Characterization of palmitoylethanolamide transport in mouse Neuro‐2a neuroblastoma and rat RBL‐2H3 basophilic leukaemia cells: comparison with anandamide

“…This process includes cellular uptake and intracellular degradation by the enzyme fatty acid amide hydrolase (FAAH) (Deutsch & Chin, 1993;Di Marzo et al, 1994). Cellular uptake of AEA has been demonstrated and characterized in neural-derived cell lines (Deutsch & Chin, 1993;Piomelli et al, 1999), primary cultures of cerebellar granule cells (Hillard et al, 1997), striatal neurons and astrocytes (Di Marzo et al, 1994;Beltramo et al, 1997), as well as in the immortalized rat basophilic leukaemia cell line RBL-2H3 (Bisogno et al, 1997;Rakhshan et al, 2000). The uptake mechanism has been shown to be mediated by a saturable, selective, temperature-dependent and Na + -independent transporter (Di Marzo et al, 1994;Beltramo et al, 1997;Hillard et al, 1997), supporting the hypothesis that the AEA uptake is carrier-mediated.…”

An anorexic lipid mediator regulated by feeding

“…The primary mechanism underlying FAE generation in mammalian tissues involves two concerted biochemical reactions: cleavage of the membrane phospholipid N-acyl phosphatidylethanolamine (NAPE), catalysed by an unknown phospholipase D; and NAPE re-synthesis, mediated by an N-acyltransferase (NAT) that is regulated by calcium ions and cyclic AMP 8,9 . After release, FAEs are transported back into cells 10 and eventually broken down to fatty acid and ethanolamine by an intracellular fatty acid amide hydrolase (FAAH) 11,12 . That animal cells release FAEs in a stimulus-dependent manner suggests that these compounds may participate in cell-tocell communication.…”