Concomitant increase by peroxisome proliferators of fatty acid-binding protein, peroxisomal beta-oxidation and cytosolic acyl-CoA hydrolase in liver.

Inductions of FABP in hepatic cytosol by administration of tiadenol and clofibric acid were studied in rats, mice and guinea-pigs. In rats and mice, [1-14C]oleic acid-binding capacity of hepatic cytosol was increased, in association with induction of peroxisomal beta-oxidation, by the administration of either the two peroxisome proliferators. The increase in [1-14C]oleic acid binding capacity was responsible for the increase in the content of FABP in livers. The peroxisome proliferators caused an induction of acyl-CoA hydrolase of lower-molecular-weight form alone in hepatic cytosol of mice, although inductions of two long-chain acyl-CoA hydrolases (higher- and lower-molecular-weight form) were brought about in hepatic cytosol of rats. Guinea-pigs lacked the peroxisome proliferator-caused inductions of FABP, peroxisomal beta-oxidation and acyl-CoA hydrolase. There was no essential difference in the inductions of FABP, acyl-CoA hydrolases and peroxisomal beta-oxidation between tiadenol and clofibric acid, despite a marked difference in their chemical structures. These results suggest that the induction of FABP is correlated with the inductions of both peroxisomal beta-oxidation and cytosolic long-chain acyl-CoA hydrolase of lower-molecular-weight form.