Induction of hepatic ornithine decarboxylase by intraperitoneal administration of caffeine in rats

I.p. administration of caffeine led to a significant increase in hepatic ornithine decarboxylase activity in rats. The enzyme activity reached approximately 10-fold above the control level 5 h after the injection of caffeine at a dose of 150 mg/kg body weight. The high level of ornithine decarboxylase activity remained for 3 h and then decreased rapidly. The enzyme activity of the kidney, however, was not significantly enhanced by the administration of caffeine. The possible mechanism of the caffeine-mediated hepatic ornithine decarboxylase induction is discussed.