Abstract
Abstract: :
Purpose: Prostamides are a hypothetical group of fatty acid metabolites that are the conceivable products of Cyclooxygenase–2 (COX–2) and specific Prostaglandin H2 (PGH2) isomerases acting sequentially on arachidonoyl ethandamide (AEA) as a substrate. The cognate molecular ions of such species have recently been reported in extracts derived from mammalian tissues. However, it is important to distinguish enzymatic products with a prostanoid skeleton from those arising from random free radical lipid peroxidation. Methods: We developed a sensitive, selective enzyme immunoassay that is capable of distinguishing the chiral, COX–2–derived products of AEA from the racemic, non–enzymatically–produced isoprostanes. The EIA was used in conjunction with mass spectroscopy to analyze the lipid extract from various tissues of wild–type, FAAH knockout, and FAAH–inhibited mice following a bolus injection of AEA. Results: When tissues of normal mice are subjected to lipid extraction following a massive bolus of AEA, no ethanolamine amides of Prostaglandin F2 (PGF2) compounds were detected. However, when fatty acid amide hydrolase (FAAH) knockout or FAAH inhibitor–treated mice were likewise challenged, significant amounts of such "prostamides" were detected. When the same samples were analyzed by stereospecific EIA, none of the products identified by mass spectroscopy could be confirmed to have precise chirality. Conclusions: The "prostamides" previously reported by others are thus determined to be non–enzymatic artifacts of a poorly controlled tissue extraction.
Keywords: oxidation/oxidative or free radical damage • pharmacology • lipids