Polyamine biosynthesis in arginine-starved and refed rats.
Growth of rats fed with a synthetic diet was studied under control conditions (arginine-rich), arginine starvation, and arginine starvation/refeeding. Hepatic polyamine concentrations and ornithine decarboxylase (ODC-)activity were determined for each population. In the livers of arginine-starved rats putrescine was decreased to half the control content within 8 days; upon refeeding, it returned to control levels within another 8 days. Spermidine content in liver tissue of arginine-starved rats remained rather stable for 7 days, but thereafter dropped to half the original value within two days. Refeeding for a period of 11 days was not enough to restore the spermidine content. The effects of arginine starvation/refeeding on spermine were very similar to those of spermidine. ODC specific activity, when correlated with growth, was higher in livers of arginine-starved rats than in control animals. Refeeding caused a decrease in ODC-activity although growth arrest was completely released. This apparent uncoupling of growth and ODC stimulation supports the theory that ODC in rat liver is regulated at three levels: first the growth-related component which is observed after stimulation by growth-hormone; second the known feed back control by polyamines, e.g. via antizyme; third the regulation at the level of the substrate supply which has been shown in this work. This is not a unique finding since very similar results have been obtained in previous experiments with the protozoan Tetrahymena thermophila. A remarkable observation of these assays was that L-ornithine, when added to the arginine-free diet was not able to substitute for L-arginine in directing growth and growth related processes.
Schertel
B
B
Institut für Biochemie I, Universität Heidelberg.
Eichler
W
W
D000818:Animals; D001120:Arginine / Q000172:deficiency*; D015317:Biogenic Polyamines / Q000096:biosynthesis*; D001835:Body Weight / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D005057:Eukaryotic Cells / Q000378:metabolism; D005260:Female; D006128:Growth / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000254:growth & development; D009929:Organ Size / Q000187:drug effects; D009952:Ornithine / Q000494:pharmacology; D009955:Ornithine Decarboxylase / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D015317:Biogenic Polyamines; D001120:Arginine; D009952:Ornithine; D009955:Ornithine Decarboxylase