Anandamide and 2-arachidonoylglycerol inhibit fatty acid amide hydrolase by activating the lipoxygenase pathway of the arachidonate cascade

Treatment of intact human neuroblastoma CHP100 cells with anandamide (arach idonoylethanolamide, AEA) or 2-arachidonoylglycerol (2-AG) inhibits intrace llular fatty acid amide hydrolase (FAAH). This effect was not associated wi th covalent modifications of FAAH, since specific inhibitors of farnesyltra nsferase, kinases, phosphatases, glycosyltransferase or nitric oxide syntha se were ineffective. Electrophoretic analysis of P-33-labelled proteins, We stern blot with antiphosphotyrosine antibodies, and glycan analysis of cell ular proteins confirmed the absence of covalent modifications of FAAH. The inhibition by AEA was paralleled by an increased arachidonate release, whic h was not observed upon treatment of cells with linoleoylethanolamide, palm itoylethanolamide, or oleoylethanolamide. Moreover, cell treatment with AEA or 2-AG increased the activity of cyclooxygenase and 5-lipoxygenase, and t he hydro(pero)xides generated from arachidonate by lipoxygenase were shown to inhibit FAAH, with inhibition constants in the low micromolar range. Con sistently, inhibitors of B-lipoxygenase, but not those of cyclooxygenase, s ignificantly counteracted the inhibition of FAAH by AEA or 2-AG. (C) 2000 A cademic Press.