Abstract
Induction of ornithine decarbcxylase by various hormones was investigated in vivo, in slices, dispersed cells and cultured strains of rat liver. The marked induction of the enzyme was observed in vivo 3 hours after injection of either insulin, glucagon, cortisol and cyclic AMP and theophylline. Hydrocortisone showed the best effect for the induction. The enzyme induction was inhibited completely by concomitant injection of either puromycin or actinomycin-D. These inhibitors suppressed the enzyme level far below than that of control. The enzyme level of control experiment increased slightly when rat liver slices were incubated for 4 hours and addition of insulin, glticagon or cyclic AMP enhanced the induction. Dexamethason showed no effect in slices. Similar effect of these hormones were observed in dispersed liver cells.
Induction of this enzyme was also observed in early growing phase of cultured cells (mouse L cell and rat liver B-2 cell) and cyclic AMP inhibited both cell growth and the enzyme induction. These observations were discussed with respect of cell growth.
