Pyruvate inhibits clofibrate-induced hepatic peroxisomal proliferation and free radical production in rats

In an effort to identify the effects of the 3-carbon compound pyruvate on free radical production, we measured hepatic total peroxisomal beta-oxidation and catalase activity and the production of lipofuscin-like products in male Sprague-Dawley rats consuming an adequate diet supplemented with pyruvate, vitamin E, or the peroxisome proliferator and free radical enhancer clofibrate for 22 days (n = 5 in each group). Clofibrate feeding induced hepatomegaly, a fivefold increase in total peroxisomal beta-oxidation activity, and a threefold increase in hepatic lipofuscin-like products (P < .05). Pyruvate but not vitamin E inhibited the increase in liver size by 70% (P < .05). Both pyruvate and vitamin E completely inhibited clofibrate-induced increases in lipofuscin-like products (P < .05). Pyruvate but not clofibrate or vitamin E increased plasma concentrations of the nitric oxide metabolites nitrite and nitrate (P < .05). We conclude that with clofibrate-induced peroxisomal proliferation and free radical production, pyruvate will inhibit peroxisomal proliferation and free radical production, inhibit free radical-induced lipid peroxidation, and enhance metabolism of nitric oxide.