Different regulation of hepatic peroxisomal beta-oxidation activity in rats treated with clofibrate and partially hydrogenated marine oil

Total RNAs from the livers of rats treated with clofibrate and partially hydrogenated marine oil (PHMO) were translated in a reticulocyte-lysate cell-free protein-synthesizing system. In clofibrate-treated rats, mRNA activity for acyl-CoA oxidase (AO), the rate-limiting enzyme of the peroxisomal beta-oxidation system, was increased markedly compared with the control, whereas the increase was less than 2-fold in PHMO-treated rats. When rats were treated with both clofibrate and PHMO in vivo, an additional increase in the hepatic AO activity was observed compared with either treatment alone, suggesting that increases in the activities of peroxisomal beta-oxidation in the rats treated with clofibrate and PHMO are based on two distinct mechanisms.