Induction of hepatic RNA-and protein synthesis by pregnenolone-16alpha-carbonitrile in rats.

Repeated administration of pregenolone-16alpha-carbonitrile (PCN) induced hepatic microsomal RNA-synthesis in female rats. The RNA that appeared with 14C-orotate in the microsomes after a 12-h pulse had maximal specific activity. Deoxycholate-soluble RNA demonstrated a higher specific activity than did its ribosomal counterpart, and both were significantly more radioactive than in the respective controls. Examination of the rate of 14C-leucine incorporation into microsome-bound polypeptides showed that the enhanced RNA-synthesis after PCN treatment resulted in an augmentation of protein-synthesis. Administration of this cyanosteroid was also associated with a significant decrease in glucose-6-phosphatase activity and an increase in the cholesterol content of rat hepatocellular microsomes, which correlate well with the degranulation of rough endoplasmic reticulum and the synchronous proliferation of smooth endoplasmic reticulum.