Vitamin E supplementation decreases basal levels of F-2-isoprostanes and prostaglandin F-2 alpha in rats

Lipid peroxidation is thought to be an important factor in the pathophysiol ogy of a number of diseases and in the process of aging. We investigated th e effects of supplementation with vitamin E on lipid peroxidation in rats. Both free radical-induced nonenzymatic- and cyclooxygenase-catalyzed enzyma tic lipid peroxidation were investigated by measuring the levels of F-2-iso prostanes (8-iso-PGF(2 alpha)) and PGF(2 alpha)-metabolite (15-K-DH-PGF(2 a lpha)), respectively, in blood, urine and liver. Samples were collected fro m control rats (n = 6) and from rats supplemented with vitamin E in the die t for 3 wk (n = 8, 20 g/kg diet of DL-alpha-tocopherol hydrogen succinate). Plasma a-tocopherol concentration and antioxidative capacity were greater in the vitamin E-supplemented rats than in the control rats (17.9 +/- 1.7 v s. 50.4 +/- 10.4 mu mol/L, P < 0.001 and 181 +/- 6 vs. 275 27 mu mol/L trol ox equivalents, P < 0.001). Urine 8-iso-PGF(2 alpha) tended to be lower in the vitamin E-supplemented rats (0.72 +/- 0.40 vs. 0.34 +/- 0.19 nmol/mmol creatinine, P = 0.056), Urine 15-K-DH-PGF(2 alpha) was lower due to vitamin E supplementation (0.97 +/- 0.38 vs. 0.56 +/- 0.21 nmol/mmol creatinine, P < 0.05), as was liver-free 8-iso-PGF(2 alpha) concentration (0.47 +/- 0.11 vs. 0.18 +/- 0.04 nmol/g, P < 0.001). Supplementation with vitamin E did n ot affect plasma 8-iso-PGF(2 alpha) or 15-K-DH-PGF(2 alpha) concentrations, liver total 8-iso-PGF(2 alpha) or plasma malondialdehyde levels. Thus, vit amin E supplementation reduced urine basal levels of biomarkers of both non enzymatic and enzymatic lipid peroxidation. In liver, vitamin E reduced the basal level of free 8-iso-PGF(2 alpha) but not total 8-iso-PGF(2 alpha).