Effects of suckling and food deprivation on the activity of citrate enzymes in the liver of the rat.

Abstract

The activity of citrate enzymes in the liver of fed and 24 hr food deprived rats of 5, 10, 20 and 30 days of age was measured. Citrate cleavage enzyme activity was highest in the rats of 5 days of age and lowest in 10 days-old rats. After 24 hr food deprivation, the activity of this enzyme fell in the rats of 5 and 30 days of age, rose in the 10 days-old rats and remained unchanged in 20 days-old animals. Citrate synthase activity was also highest in the 5 days-old rats. It was lowest in the 20 days-old rats. The activity of this enzyme fell in 5 days-old rats, rose in 20 days-old rats and remained unchanged in 10 and 30 days-old animals after 24 hr food deprivation. NADH-linked isocitrate dehydrogenase activity was also highest in the 5 days-old rats. It was lowest in the 30 daysold animals. The activity of this enzyme rose in the 10, 20 and 30 days-old rats and fell in the 5 days-old animals after food deprivation. NADPH-linked isocitrate dehydrogenase activity was highest in the 30 days-old rats and lowest in the 20 days-old animals. Food deprivation lead to a rise in the activity of this enzyme in 20 days-old rats, a fall in 10 days-old rats and no change in the other two age groups. The levels of enzyme activity observed in the rats have been related to changes in the steady state concentration of liver citrate that occur during development in fed and food deprived rats.