Excess vitamin A and the metabolism of carbohydrates: variation of enzyme activities in gingiva of rats submitted to excess vitamin A, vitamin A plus cortisol and vitamin A plus ascorbic acid.

The effect of 1 to 5 doses of 15,000 I.U. of vitamin A on some enzymes of the carbohydrate metabolism in gingival tissue from rats was studied. Vitamin A feeding resulted in a significant increase in the activities of hexokinase and pyruvate kinase with the different doses tested. A reduction in the activity of phosphofructokinase was observed with 2 and 4 doses. The administration of ascorbic acid along with vitamin A, did not prevent the effects of vitamin A on the activities of the enzymes studied. The data on the enzyme activities in the groups simultaneously fed on vitamin A and cortisol may indicate an additive effect of these compounds.