Polyamine Metabolism in Rat Liver: Effect of Starvation and Refeeding

Abstract

In rats, effects of starvation and subsequent refeeding on hepatic polyamine-synthesizing enzymes (ornithine decarboxylase, S-adenosyl-methionine decarboxylase) and on polyamine contents (putrescine, spermidine, spermine), were examined. Following 12 hours of starvation, ornithine decarboxylase activity was reduced markedly (to 13% of controls) and was decreased to levels near zero after 3 days of starvation, whereas S-adenosylmethionine decarboxylase activity declined less drastically (to 50% of controls). This fall in enzyme activities was in good accord with putrescine and spermidine contents which were found to be decreased significantly in rat livers under these conditions. On refeeding, within 3 hours ornithine decarboxylase activity increased about 7-fold as compared to controls, whereas the rise in Sadenosylmethionine decarboxylase activity was less pronounced (to 125% of controls). These changes were accompanied by a normalization of the levels of putrescine and spermidine. Interestingly, hepatic spermidine and RNA contents fluctuated concomitantly. DNA and spermine levels, however, remained almost unchanged during starvation and refeeding periods.

Key words

Rat Liver - Starvation - Refeeding - Ornithine Decarboxylase - S-Adenosylmethionine Decarboxylase - Polyamines - Putrescine - Spermidine - Spermine - Nucleic Acids

1 S. Domschke's present address: Med. Univ.Klinik Erlangen-Nürnberg, D-8520 Erlangen/Germany

2 The abbreviations used in this study are: ODC: L-ornithine decarboxylase (E.C.4.1.1.17); SAMD: S-adenosyl-L-methionine decarboxylase (E.C. not defined); PUT: putrescine; SPD: spermidine; SP: spermine.