Oxidative stress and CLA

CLA has been reported to be involved in oxidative stress, as a product , as an antioxidant and as a prooxidant while other papers strongly argue that CLA might not influence oxidative stress at all, thus it remains to be clarified. The aim of this study was to investigate how a 50/50 mixture of CLA isomers may influence formation of oxidative stress markers in two well known experimental models, carbon tetrachloride (CCl4) and LPS intoxication in rats. We evaluated the formation of malonyldialdehyde (MDA), nitrites, arachidonic hydroperoxides (ARAHP) and one of the most reliable markers, 8-iso-PGF2α isoprostane (IP), and its peroxisomal beta oxidation metabolite, 2,3 diinor (DIN). The results showed that CLA did not modify significantly formation of MDA, nitrites and ARAHP in liver and plasma of rats challenged with CCl4 or LPS. However, CLA feeding resulted in a higher detection of IP in both plasma and liver with a concomitant decrease of its peroxisomal beta oxidation DIN. Analyses of CLA peroxisomal beta oxidation metabolite CD 16:2 clearly showed that the increase of IP was due to an its impaired metabolism to DIN for a competition with CLA in peroxisomes, rather than an increased oxidative stress. In conclusion, there were no evidences that CLA influences oxidative stress and that the measurement of IP is not a reliable marker of ongoing oxidative stress in these experimental conditions , especially in the absence of other markers. However, whether this could explain the increase of IP during CLA administration in humans is suggestive but not conclusive with our data.