Expression of endocannabinoid synthetic enzyme mRNAs is correlated with cannabinoid 1 receptor mRNA in the mouse brain

The two principal endocannabinoids, N-arachidonoyl-ethanolamine (anandamide) and 2-arachidonoyl-glycerol (2-AG), are synthesized from arachidonic acid (AA) and AA is released as they are degraded. Therefore, the function of endocannabinoids is closely linked to AA, but the exact relationships have not been clarified, especially with respect to endocannabinoid metabolism. In the present study, oil rich in AA was administered (0, 100, 200 and 300 microl) orally to male mice for 7 days. Phospholipase D (PLD), fatty acid amide hydrolase (FAAH), diacyl-glycerol lipase (DAGL), monoacyl-glycerol lipase (MAGL) and cannabinoid 1 (CB1) receptor mRNA expressions were determined in the whole brain. No changes in the expression of any gene investigated were detected following AA treatment. However, it was demonstrated that the expression of the CB1 receptor was positively correlated with PLD, FAAH and DAGL expression. This suggests that expression of the CB1 receptor is closely coordinated with that of the enzymes which synthesize its ligands.