Correlation between circadian rhythms of polyamine synthesis and cell proliferation in rat liver.
In rats fed ad libitum, a marked circadian rhythm with a peak at night was observed in the hepatic level of ornithine decarboxylase (ODC) [EC 4.1.1.17], the enzyme for the first step of polyamine synthesis. A similar rhythm was found in the hepatic content of putrescine, but not of spermidine or spermine. The mitotic activity of the liver also exhibited a clear rhythm with a peak in the daytime. The rhythms of both ODC and mitosis were generated by cyclic ingestion of proteinous food, since the peaks shifted when rats were meal-fed and both activities disappeared on starvation or protein deprivation. The close parallel between the rhythms suggested that synthesis of polyamine, especially that of putrescine, was a prerequisite for the rhythmic growth of liver. The dietary induction of hepatic ODC depended on the nutritive value of dietary protein; zein or gelatin was effective only when supplemented with limiting amino acids and there was a good correlation between the hepatic ODC level and the relative growth rate.
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002262:Carboxy-Lyases / Q000096:biosynthesis*; D002940:Circadian Rhythm; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D007328:Insulin / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000502:physiology*; D008112:Liver Glycogen / Q000378:metabolism; D008297:Male; D008938:Mitosis; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D011700:Putrescine / Q000378:metabolism*; D051381:Rats; D013095:Spermidine / Q000378:metabolism*; D013096:Spermine / Q000378:metabolism*
D000596:Amino Acids; D007328:Insulin; D008112:Liver Glycogen; D003609:Dactinomycin; D013096:Spermine; D003513:Cycloheximide; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; D013095:Spermidine; D011700:Putrescine