Effects of development on acetoacetyl-CoA synthetase biosynthesis in rat liver

In order to investigate the physiological role of acetoacetyl-CoA synthetase (acetoacetate-CoA ligase, EC 6.2.1.16), a cytosolic acetoacetate-activating enzyme, the effects of animal development on the activity and content of the enzyme were examined in rat liver. In male rats, the enzyme specific activity increased 21-fold at 4 weeks of age from that at 2 weeks of age, and then gradually decreased, while in female rats, it increased similarly to that of male rats, but further increased, reaching a maximum about 3-fold higher than that of male rats, at 6 weeks of age. The developmental patterns of the enzyme content correlated with that of the enzyme specific activity. These results indicate that changes in this enzyme activity and content during the developmental process might influence the rate of ketone body utilization for the formation of physiologically important lipidic substances in rat liver.