Selective response of liver enzymes to the administration of different diets after fasting

The technique of feeding, following a fasting period, is considered a good tool for the study of the dependence of enzyme activities on the nature of the diet.

Abstract

The activities of glucokinase, UDPG-glycogen transglucosylase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, referred to 100 g. of body weight, decreased in the liver of animals fed with a high-fat diet for 6 days and were maintained at normal levels in rats fed a high-carbohydrate, fat-free diet. The enzymes decreased after a 48-hr, fasting period and returned to normal values after subsequent feeding with an equilibrated diet. The administration of a high-fat diet did not induce recovery of enzyme activities; only 6-phosphogluconato dehydrogenase recovered partially. In contrast, following administration of a diet consisting solely of carbohydrates, glucokinase recovered to normal levels within 1 day, while glucose 6-phosphate and 6-phosphogluconate dehydrogenases remained at the same low levels observed in fasted animals. The technique of feeding, following a fasting period, is considered a good tool for the study of the dependence of enzyme activities on the nature of the diet.