[Changes in the activities of NAD- and NADP-specific isocitrate dehydrogenases in the brain and liver during the postembryonic development of animals].

The activities of NAD- and NADP-specific isocitrate dehydrogenases (ICDH) were investigated in subcellular fractions of rat brain and liver. Animals of different age groups were used: newborn, 10-, 20-, 30-, 40-days old and adult rats. It was shown that NAD-ICDH activity rose sharply in adult brain mitochondria as compared with that of developing animals. The NAD-dependent pathway of isocitrate oxidation predominated in mitochondria of both developing and adult brain. The activity of NADP-ICDH decreased in brain mitochondria and cytoplasm in the course of development. Some changes in the distribution of enzyme activity between subcellular fractions were also found in adult brain. The activity of mitochondrial NADP-ICDH was higher than that of newborn animals.