NUCLEIC ACID PATTERNS IN RAT LIVER FOLLOWING HYPOPHYSECTOMY AND GROWTH HORMONE ADMINISTRATION¹

Abstract

THE administration of purified pituitary growth hormone to either hypophysectomized or intact rats results in nitrogen retention and increased protein synthesis. However, the mechanisms involved are unknown. Recently, several investigators have described high concentrations of ribosenucleic acid (RNA) in cells actively engaged in protein synthesis (Brachet, 1950; Caspersson, 1950; Davidson, 1950) and increases of this nucleic acid in cells which have an accelerated rate of protein synthesis. This constitutes circumstantial evidence that the concentration of RNA in cells may be related to their protein anabolic activity. That growth hormone may exert its protein anabolic effect by a mechanism involving nucleic acid metabolism is suggested by at least two recent studies. Geschwind et al. (1950) have shown that hypophysectomy results in a lowering of the RNA concentration of rat liver, and that growth hormone treatment of hypophysectomized rats restores the liver RNA concentration to normal. Further, Kalter et al. (1950) have described enhancement of the growth rate of influenza virus in mice treated with purified pituitary growth hormone.