EFFECT OF AN ELEMENTAL VS A COMPLEX DIET ON POLYAMINE METABOLISM IN RAT ISOLATED ENTEROCYTES

Background: Polyamines play an important role in the proliferation and differentiation of enterocytes. Ornithine decarboxylase (ODC) is the rate-limiting enzyme for polyamine biosynthesis. Elemental diets, prov iding easily absorbable nutrients such as free amino acids, are used i n clinical practice to treat growth failure and malnutrition. They are very different from complex diets normally consumed. Little informati on is available about the influence of elemental diets on metabolic ca pacities of enterocytes. This study was undertaken in rats to assess t he effects on polyamine metabolism of an elemental diet compared with a complex diet. Methods: Rats were fed the elemental diet (group ED) o r the control diet (group C) for 14 days. The dietary intakes were iso caloric and isonitrogenous in groups C and ED. Villous enterocytes wer e then isolated and metabolic capacities or enzyme activities were ass essed. Results: Both the enterocyte capacity to decarboxylate ornithin e through ODC (measured in viable enterocytes) and ODC activity (measu red in homogenates) were severely decreased in group ED. The polyamine content in enterocytes, however, was maintained at a similar level in both groups. This coincided with a decrease in the main enzymatic act ivity responsible for putrescine catabolism (ie, diamine oxidase activ ity) in group ED. Conclusions: Although nutrition manipulation was sho wn to alter polyamine biosynthesis in this study, the polyamine homeos tasis was probably maintained, at least in part, through down-regulati on of diamine oxidase.