Anandamide (N arachidonoylethanolamide), an arachidonic acid derivative, is an endogenous ligand for cannabinoid receptors, which are members of the G protein (Gi) coupled receptors family. Ananamide is mainly found in central nervous system, immune system and uterus etc and mimics most of the effects of (-)Δ 9 tetrahydrocannabinoid [(-)Δ 9 THC], a psycoactive derivative of marijuana. Fatty acid amide hydrolase (FAAH), which is involved in hydrolyzing anandamide to arachidonic acid and ethanolamide, may quickly regulate level of anandamide in vivo .