Human intervention trials have shown that conjugated linoleic acid (CLA) intake increased plasma levels of 8-iso-PGF2a isoprostane (IP). Isoprostanes can be indicative of oxidative stress and are increased in many disease states for example Cardiovascular disease. The aim of this study was to verify if CLA is able to influence IP formation and/or metabolism and by which mechanism. Rats fed CLA were challenged with a single dose of carbon tetrachloride (CCl4). The results showed that IP and its precursor arachidonic acid hydroperoxides increased significantly in the liver of rats challenged with CCl4, irrespective of the diet. However, the peroxisomal beta oxidation products of IP, 2,3, diinor (DIN), was found only in the free form and was significantly lower in the CLA group with respect to the control group. This suggests that increased IP due to CLA intake may be caused by reduced IP metabolism in the peroxisomes and not by oxidative stress. To further investigate this possibility at the cellular level, we incubated human fibroblasts from healthy subjects or patients with adrenoleukodystrophy (ALD), with CLA and/or commercially available IP. In both normal and ALD cells, the presence of CLA significantly inhibited the formation of DIN from IP. We may conclude that both "in vitro" and "in vivo" studies strongly suggest that CLA may impair IP catabolism in peroxisomes. Therefore CLA does not induce oxidative stress in agreement with previous data showing other markers of oxidative stress are not affected by CLA intake in humans.
Metabolism of 8-iso-PGF2 isoprostane is impaired by conjugated linoleic acid (CLA) / Marianne O Shea; Anna Iannone; Anna Petroni; Elisabetta Murru; Lina Cordeddu; Gianfranca Carta; Maria Paola Melis; Stefania Bergamini; Lara Della Casa; Milena Blasevich; Romina Carissimi; De Santis E; Sebastiano Banni. - In: THE FASEB JOURNAL. - ISSN 0892-6638. - 21:(2007), pp. 339-339. ((Intervento presentato al convegno 83 Meeting of the Federation of American Societies for Experimental Biology.