Abstract
The endocannabinoid system plays an important role in numerous physiological processes including mood, appetite, and pain-sensation. A critical compound in maintaining cannabinoid tone is the endocannabinoid anandamide (AEA). We have recently shown that AEA is metabolized by several different human cytochrome P450s (P450) to form a number of metabolites; one of which exhibits an increased biological activity. CYP3A4, one of the major P450s involved in the metabolism of AEA, produces four major metabolites. One of these metabolites, 5,6 epoxyeicosatrienoic acid ethanolamide (5,6-EET-EA), exhibits a much higher affinity than AEA for the cannabinoid 2 receptor (CB-2) and leads to a marked decrease in intracellular cAMP levels in cells expressing CB-2. There are multiple human alleles of CYP3A4 and the CYP3A4.4 allele has been shown to exhibit a significant decrease in activity. Recombinant CYP3A4*4 was expressed in E.coli, and was demonstrated to produce 60% less 6-OH-testosterone than the wild type 3A4 (WT) in a reconstituted system. The metabolism of AEA by the WT and the CYP3A4.4 variant were investigated. The mutant produced 60% less of the four EET-EA metabolites than the WT. The mutant also produced a new peak on LC-MS not seen with the WT that corresponded to 19-HETE-EA. In addition, the mutant produces four novel peaks at m/z 380, which correspond to the addition of 2 oxygen atoms, possibly to form a peroxide bond. These data indicate that individuals expressing the CYP3A4.4 allele may exhibit significant variations in the metabolism of AEA as well as any other compounds resembling AEA.
Footnotes
- Received April 2, 2010.
- Accepted August 11, 2010.
- The American Society for Pharmacology and Experimental Therapeutics