Identification of a new class of molecules, the arachidonyl amino acids, and characterization of one member that inhibits pain

In mammals, specific lipids and amino acids serve as crucial signaling mole cules. In bacteria, conjugates of lipids and amino acids (referred to as li poamino acids) have been identified and found to possess biological activit y. Here, we report that mammals also produce lipoamino acids, specifically the arachidonyl amino acids. We show that the conjugate of arachidonic acid and glycine (N-arachidonylglycine (NAGly)) is present in bovine and rat br ain as well as other tissues and that it suppresses tonic inflammatory pain . The biosynthesis of NAGly and its degradation by the enzyme fatty acid am ide hydrolase can be observed in rat brain tissue. In addition to NAGly, bo vine brain produces at least two other arachidonyl amino acids: N-arachidon yl gamma -aminobutyric acid (NAGABA) and N-arachidonylalanine. Like NAGly, NAGABA inhibits pain. These findings open the door to the identification of other members of this new class of biomolecules, which may be integral to pain regulation and a variety of functions in mammals.