Changes in activity of some enzymes involved in glucose utilization and formation in developing rat liver.
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ABSTRACT:
SUBMITTER: Vernon RG
PROVIDER: S-EPMC1198506 | biostudies-other | 1968 Jan
REPOSITORIES: biostudies-other
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Project description:1. The effects of premature weaning on to normal and high-glucose diets and of normal weaning on to high-protein and high-fat diets on the activities of hepatic enzymes involved in both the utilization of glucose and the formation of glucose by gluconeogenesis in rats during the weaning period were investigated. 2. The effects of weaning and high-glucose diets were, in general, to bring about increases in the activities of enzymes involved in glucose utilization and a more rapid decrease of the activities of the gluconeogenic enzymes towards normal adult values. 3. The effects of weaning on to high-fat and high-protein diets were, in general, to lower the rate of increase in activities of the enzymes involved in glucose utilization, and to prevent the decrease in activity of the gluconeogenic enzymes that occurs during normal weaning. 4. The changes in the activity of cytoplasmic phosphopyruvate carboxylase appear to be of special significance; this and other results are in keeping with current theories about the pathways and control of gluconeogenesis. 5. The activity of ATP citrate lyase appears to be particularly important in lipid formation. 6. The results are interpreted in terms of the known adaptive behaviour of these enzymes in the adult rat. The roles of enzyme development and of enzyme adaptation in the elaboration of metabolic homoeostasis in the weanling rat are discussed.
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Project description:The development of key enzyme activities concerned with glucose metabolism was studied in six regions of the rat brain in animals from just before birth (-2 days) through the neonatal and suckling period until adulthood (60 days old). The brain regions studied were the cerebellum, medulla oblongata and pons, hypothalamus, striatum, mid-brain and cortex. The enzymes whose developmental patterns were investigated were hexokinase (EC 2.7.1.1), aldolase (EC 4.1.2.13), lactate dehydrogenase (EC 1.1.1.27) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49). Hexokinase, aldolase and lactate dehydrogenase activities develop as a single cluster in all the regions studied, although the timing of this development varies from region to region. Glucose-6-phosphate dehydrogenase activity, however, declines relative to glycolytic enzyme activity as the brain matures. When the different brain regions are compared, it is clear that the medulla develops its glycolytic potential, as indicated by its potential enzyme activity, considerably earlier than the other regions (hypothalamus, striatum and mid-brain), with the cortex and cerebellar activities developing even later. This enzyme developmental sequence correlates well with the neurophylogenetic development of the brain and adds support to the hypothesis that the development of the potential for glycolysis in the brain is a necessary prerequisite for the development of neurological competence.
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