Metabolic Effects of Dietary Purine and Pyrimidine Bases in Rats

Abstract

The effect of dietary nucleic acid constituents (purine and pyrimidine bases) on the metabolism of serum and urinary uric acid, allantoin, creatinine, urea nitrogen and urea was examined in the rat. The results were compared with the morphological changes. It was found that guanine is readily converted to uric acid and allantoin, whereas adenine, due to its unique metabolism, is metabolized quite differently from guanine and pyrimidine bases. Furthermore, an increase of creatinine, urea nitrogen and urea in the serum as well as a reduction in their urine excretion was observed in rats fed on the adenine diet. Dietary adenine produced a nephrotoxic condition as reflected in the histopathological changes. That is, deposits of amorphous birefringent crystal (2,8-dihydroxy-adenine) with formation of foreign body granuloma were demonstrated in the tubular lumina and the interstitium of the kidney, and also in the urinary bladder and urine. However, there were not seen in the glomeruli and other organs. On the other hand, in the kidneys of rats fed on guanine, uracil, cytosine and yeast RNA diets, these histopathological changes were not noticed.