An endogenous CB1 and CB2 receptor agonist (Kis = 25.3-472 and 145-1,400 nM, respectively); the most abundant molecular species of MAG found in rat brain; formation is calcium-dependent and is mediated by the activities of PLC and DAG lipase; induces a rapid, transient increase in intracellular free calcium in NG108-15 neuroblastoma X glioma cells through a CB1 receptor-dependent mechanism at a concentration of 0.3 nM; metabolized in vitro by MAG lipase and FAAH, with MAG lipase likely being the principle metabolizing enzyme in vivo,