Effects of dietary polyamines and clofibrate on metabolism of polyamines in the rat

The activities of catalase, polyamine oxidase, diamine oxidase, ornithine d ecarboxylase, and peroxisomal beta-oxidation were assayed in homogenates fr om liver and small intestinal mucosa of rats which had been fed either a di et very low in polyamines or a diet containing five times the levels of die tary polyamines (putrescine, spermine, and spermidine) found in a standard mt diet. In rats fed the high polyamine diet, hepatic activities of catalas e and polyamine oxidase were significantly decreased. Levels of the other a ctivities were unchanged, except that intestinal ornithine decarboxylase wa s decreased in mts tr eared simultaneously with clofibrate, the high polyam ine diet restored activities of catalase, ornithine decarboxylase, and poly amine oxidase back to levels found in mts fed the low polyamine diet. The e xpected increase in activity of peroxisomal beta-oxidation was observed, al though this was somewhat diminished in rats fed the high polyamine diet. In testinal diamine oxidase activity was stimulated by clofibrate, particularl y in mts fed the high polyamine diet. For the duration of the experiment (2 0 days), levels of putrescine, spermine, and spermidine ill blood remained remarkably constant irrespective of treatment, suggesting that polyamine ho meostasis is essentially independent of dietary supply of polyamines. It is suggested that intestinal absorption/metabolism of polyamines is of signif icance in this respect. Treatment with clofibrate appeal-ed to alter polyam ine homeostasis. (C) Elsevier Science Dac. 1999. All rights reserved.