Assay of Monoacylglycerol Lipase Activity

Monoacylglycerol lipase (MGL/MAGL/MGLL) is a serine hydrolase involved in the biological deactivation of the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG). 2-AG is the most abundant endogenous lipid agonists for cannabinoid receptors in the brain and elsewhere in the body. In the central nervous system (CNS), MGL is localized to presynaptic nerve terminals of both excitatory and inhibitory synapses, where it controls the regulatory actions of 2-AG on synaptic transmission and plasticity. In this chapter, we describe an in vitro method to assess MGL activity by liquid chromatography/mass spectrometry (LC/MS)-based quantitation of its reaction product. The method may be used to determine basal or altered MGL activity in cells or tissues after pharmacological, genetic, or biological interventions. In addition, the assay can be used for MGL inhibitor screening using purified recombinant enzyme or MGL-overexpressing cells.