Effect of gamma radiation on dietary and hormonal induction of enzymes in rat liver.

The dietary induction of serine dehydrase, produced by the oral intubation of hydrolyzed casein to protein-depleted rats, is markedly inhibited by doses of gamma-radiation of 400 roentgens or higher provided the irradiation is given within an hour after the initial dose of casein. If the irradiation is delayed until 7 hours after the initial dose of casein, induction is not inhibited. In contrast, the cortisone induction of tyrosine alpha-ketoglutarate transaminase is not inhibited by doses of gamma-radiation up to 3200 roentgens; in some instances hormonal induction of this enzyme appears to be enhanced by irradiation.