ASCORBIC ACID METABOLISM IN HYPOTHYROID RATS

Abstract

Male albino rats were fed methylthiouracil (0.2%) and after 6 weeks their ascorbic acid, dehydroascorbic acid, and diketogulonic acid were determined in liver, kidney, and urine, while only total ascorbic acid was determined in blood. Activities of ascorbic acid synthesizing enzymes, D-glucurono-δ-lactone hydrolase, L-gulono-γ-lactone hydrolase, and L-gulono-γ-lactone oxidase were estimated in liver. The activities of degrading enzymes, dehydroascorbatase and 2, 3-diketoaldonate decarboxylase, were also studied in liver and kidney. In hypothyroid rats there was a significant decrease in the ascorbic acid level and dehydro-ascorbic acid content of liver. On the other hand there was a marked increase in the diketogulonic acid content of the liver. The content of ascorbic acid in urine of hypothyroid rats increased slightly, while there was no change in the dehydroascorbic acid and diketogulonic acid content. Total ascorbic acid in blood was found to be unaltered. There were no alterations in the activities of L-gulono-γ-lactone oxidase, D-glucurono-δ-lactone hydrolase and L-gulono-γ-lactone hydrolase. Appreciable increases in the activity of dehydroascorbatase and 2, 3-diketoaldonate decarboxylase, were observed in liver of hypothyroid rats.