Fatty acyl-CoA oxidase activity is induced before long-chain acyl-CoA hydrolase activity and acyl-CoA binding protein in liver of rat treated with peroxisome proliferating 3-thia fatty acids.

1. In this study we explored the relationship between specific acyl-CoA esters and induction of acyl-CoA binding protein (ACBP) and enzymes related to the proliferation of peroxisomes. Male Wistar rats were administered a single dose (150 mg/day/kg) of sulphur-substituted fatty acid analogues, and the effects of tetradecylthioacetic acid and 3-thiadicarboxylic acid, which both act as peroxisome proliferators, were compared with the effects of tetradecylthiopropionic acid and palmitic acid which do not induce peroxisome proliferation. 2. The hepatic level of total long-chain acyl-CoA was significantly increased within 12 h of feeding these fatty acids, except in rat fed tetradecylthioacetic acid. Hplc chromatograms of liver extracts prepared from rat fed tetradecylthioacetic acid showed that tetradecylthioacetyl-CoA ester accumulated in the liver 4 h after feeding and had disappeared after 24 h. In liver extracts of the tetradecylthiopropionic acid-treated rat tetradecylthiopropionyl-CoA was not observed, but the appearance of a new long-chain acyl-CoA ester, probably a metabolite of tetradecylthiopropionic acid, was detected. This new peak reached a maximum 4h after feeding. In rat fed tetradecylthioacetic acid and 3-thiadicarboxylic acid the hepatic level of fatty acyl-CoA oxidase mRNA increased 8 h after feeding, while the acyl-CoA oxidase activity had increased after 12 h. 3. The early accumulation of specific tetradecylthioacetyl-CoA suggests that this ester may be a possible mediator of the induction of fatty acyl-CoA oxidase. The level of hepatic acyl-CoA binding protein, long-chain acyl-CoA hydrolase activity and long-chain acyl-CoA synthetase activity did not change after a single dose of all four fatty acids. Prolonged administration of 3-thia fatty acids resulted, however, in a dose- and time-dependent increase in hepatic ACBP content and ACBP mRNA level. The amount of ACBP increased in parallel to the long-chain acyl-CoA hydrolase activity. The correlated induction of fatty acyl-CoA binding protein and long-chain acyl-CoA hydrolase seems to be dependent on a sustained accumulation of total long-chain acyl-CoA esters.