A catalytically silent FAAH-1 variant drives anandamide transport in neurons

The endocannabinoid anandamide is removed from the synaptic space by a selective transport system, expressed in neurons and astrocytes, which remains molecularly uncharacterized. Here we describe a partly cytosolic variant of the intracellular anandamide-degrading enzyme, fatty acid amide hydrolase-1 (FAAH-1), termed FAAH-like anandamide transporter (FLAT), which lacks amidase activity but binds anandamide with low micromolar affinity and facilitates its translocation into cells. Known anandamide transport inhibitors, such as AM404 and OMDM-1, block these effects. Additionally, we identify a competitive antagonist of the interaction of anandamide with FLAT, the phthalazine derivative ARN272, which prevents anandamide internalization in vitro, interrupts anandamide deactivation in vivo, and exerts profound analgesic effects in rodent models of nociceptive and inflammatory pain, which are mediated by CB(1) cannabinoid receptors. The results identify FLAT as a critical molecular component of anandamide transport in neural cells and a potential target for therapeutic drugs.