Stimulation of nuclear protein synthesis in rat liver after phenobarbital administration

Abstract

When a 40 min pulse of leucine-3H was administered to rats 2 hrs after 75 mg/kg of phenobarbital (Pb), there was a 70% increase above control in labeling of microsomal protein and of a nuclear protein fraction extracted with 1 M NaCl. When a 40 min pulse of labeled leucine was given 24 hrs after a single injection of Pb (75 mg/kg), there was a 42% stimulation in the specific activity of microsomal protein but an 87% enhancement, compared to control, in the nuclear protein fraction. Separation of the nuclear fraction on DEAE-cellulose columns indicated that there was a 5-fold stimulation in the specific activity of one of the protein peaks from the nuclear protein fraction of the Pb-treated rats. These data indicate that Pb administration enhances the synthesis of various protein fractions in hepatic cells and suggest that these events may be involved in the enzyme induction produced by this drug.