Role of dihydropyrimidine dehydrogenase in the uridine nucleotide metabolism in the rat liver

Abstract

The activity of dihydropyrimidine dehydrogenase, which is the rate-limiting enzyme in the catabolism of pyrimidine, in livers of 5-day-old rats increased 48 h after glucocorticoid injection. The increase in the activity of dihydropyrimidine dehydrogenase by glucocorticoid administration and by aging did not decrease the uridine, uracil and sigma UMP (the sum of acid-soluble uracil 5'-nucleotides) pool in liver. The increase of liver uracil by a uridine diet not increase dihydropyrimidine dehydrogenase activity. The increase of liver uracil did not increase dihydropyrimidine dehydrogenase activity. However, dihydropyrimidine dehydrogenase activity which increased after glucocorticoid treatment increased the pyrimidine-degradation rate in rat livers and hepatocytes. Pyrimidine catabolism pathway in liver may play an important role in degradation of dietary pyrimidines and pyrimidines which are administered in the form of medicines as 5-fluorouridine.