Effect of aging on the prostaglandin-synthesizing system in rat liver

The effect of aging on the prostaglandin-synthesizing system in the rat liver was studied. No alteration in prostaglandin synthesis was observed during the period from 2 to 72 weeks, however, after 72 weeks the prostaglandin-synthesizing activity decreased gradually. At 92 weeks, the enzyme activity was down to 60% comparing with the young level. But the ratio of the production rate of prostaglandin E2 to that of prostaglandin F2 alpha remained constant throughout the experimental period. On the other hand, the activity of the liver in incorporating arachidonic acid into phospholipids increasing gradually with aging as a mirror image of prostaglandin synthesis. In young rats, the production of prostaglandins was significantly increased by phenobarbital-treatment, while in old rats this increase in prostaglandin synthesis failed to appear.