Regulation of alternative pathways of glucose metabolism in rat heart in alloxan diabetes: Changes in the pentose phosphate pathway

Certain key enzymes of alternative pathways of glucose metabolism, of amino acid metabolism and of redox systems have been measured in hydra and this profile compared with mammalian differentiated tissues with a view to locating pathways of specific importance in hydra. There was a marked constant proportionality in the major part of the enzymes investigated, the profile suggested a metabolic pattern geared to utilization of amino acids as a carbon source for biosynthesis and energy production and to the production and conservation of pyruvate. The importance of conversion to ionized forms was noted. The most notable specific proportion changes were the exceptionally low lactate dehydrogenase, malic enzyme and the relatively high citrate synthase. The proximal-distal gradients in hydra were examined and these gradients suggested a switch to a more anaerobic type of metabolism and an elevation of the pentose phosphate pathway as the basal region was approached. Measurements of the formation of 14CO2 from specifically labelled glucose provided additional evidence for the functional activity and polarity of the pentose phosphate pathway in hydra. The effect of oligomycin, which can reverse polarity in hydra, had a significant effect on gradients of enzymes eliminating all except that observed for G6P dehydrogenase. The profile suggested a movement towards a more anaerobic type of metabolism, in keeping with the known biochemical action of this inhibitor. It is suggested that redox states and/or phosphorylation states may be featured in the positional information of cells in hydra.

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The Pentose Phosphate Pathway and Pyruvate Carboxylation after Neonatal Hypoxic-Ischemic Brain Injury

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2014.8 ◽

2014 ◽

Vol 34 (4) ◽

pp. 724-734 ◽

Cited By ~ 27

Author(s):

Eva MF Brekke ◽

Tora S Morken ◽

Marius Widerøe ◽

Asta K Håberg ◽

Ann-Mari Brubakk ◽

...

Keyword(s):

Oxidative Stress ◽

Glucose Metabolism ◽

Pentose Phosphate Pathway ◽

De Novo ◽

Pentose Phosphate ◽

Adult Brain ◽

Resonance Spectroscopy ◽

Neonatal Brain ◽

Artery Ligation ◽

Pyruvate Carboxylation

The neonatal brain is vulnerable to oxidative stress, and the pentose phosphate pathway (PPP) may be of particular importance to limit the injury. Furthermore, in the neonatal brain, neurons depend on de novo synthesis of neurotransmitters via pyruvate carboxylase (PC) in astrocytes to increase neurotransmitter pools. In the adult brain, PPP activity increases in response to various injuries while pyruvate carboxylation is reduced after ischemia. However, little is known about the response of these pathways after neonatal hypoxia-ischemia (HI). To this end, 7-day-old rats were subjected to unilateral carotid artery ligation followed by hypoxia. Animals were injected with [1,2-13C]glucose during the recovery phase and extracts of cerebral hemispheres ipsi- and contralateral to the operation were analyzed using 1H- and 13C-NMR (nuclear magnetic resonance) spectroscopy and high-performance liquid chromatography (HPLC). After HI, glucose levels were increased and there was evidence of mitochondrial hypometabolism in both hemispheres. Moreover, metabolism via PPP was reduced bilaterally. Ipsilateral glucose metabolism via PC was reduced, but PC activity was relatively preserved compared with glucose metabolism via pyruvate dehydrogenase. The observed reduction in PPP activity after HI may contribute to the increased susceptibility of the neonatal brain to oxidative stress.

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Wnt5a Increases the Glycolytic Rate and the Activity of the Pentose Phosphate Pathway in Cortical Neurons

Neural Plasticity ◽

10.1155/2016/9839348 ◽

2016 ◽

Vol 2016 ◽

pp. 1-13 ◽

Cited By ~ 5

Author(s):

Pedro Cisternas ◽

Paulina Salazar ◽

Carmen Silva-Álvarez ◽

L. Felipe Barros ◽

Nibaldo C. Inestrosa

Keyword(s):

Glucose Metabolism ◽

Wnt Signaling ◽

Pentose Phosphate Pathway ◽

Neurodegenerative Disorders ◽

Metabolic Flux ◽

High Energy ◽

Pentose Phosphate ◽

The Brain ◽

Glycolytic Rate

In the last few years, several reports have proposed that Wnt signaling is a general metabolic regulator, suggesting a role for this pathway in the control of metabolic flux. Wnt signaling is critical for several neuronal functions, but little is known about the correlation between this pathway and energy metabolism. The brain has a high demand for glucose, which is mainly used for energy production. Neurons use energy for highly specific processes that require a high energy level, such as maintaining the electrical potential and synthesizing neurotransmitters. Moreover, an important metabolic impairment has been described in all neurodegenerative disorders. Despite the key role of glucose metabolism in the brain, little is known about the cellular pathways involved in regulating this process. We report here that Wnt5a induces an increase in glucose uptake and glycolytic rate and an increase in the activity of the pentose phosphate pathway; the effects of Wnt5a require the intracellular generation of nitric oxide. Our data suggest that Wnt signaling stimulates neuronal glucose metabolism, an effect that could be important for the reported neuroprotective role of Wnt signaling in neurodegenerative disorders.

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Pathways of glucose catabolism in Mycobacterium smegmatis

Canadian Journal of Microbiology ◽

10.1139/m76-201 ◽

1976 ◽

Vol 22 (9) ◽

pp. 1374-1380 ◽

Cited By ~ 12

Author(s):

N. Jayanthi Bai ◽

M. Ramachandra Pai ◽

P. Suryanarayana Murthy ◽

T. A. Venkitasubramanian

Keyword(s):

Glucose Metabolism ◽

Carbon Source ◽

Pentose Phosphate Pathway ◽

Mycobacterium Smegmatis ◽

Pentose Phosphate ◽

Minor Role ◽

Key Enzymes ◽

Glucose Catabolism ◽

A Minor ◽

Cells Cultured

Glucose metabolism in Mycobacterium smegmatis was investigated by the radiorespirometric method and by assaying for key enzymes of the major energy-yielding pathways. Glucose is oxidized in this organism mainly through the Embden–Meyerhof–Parnas pathway, irrespective of the carbon source used for growth. The pentose phosphate pathway plays only a minor role and its extent depends on the carbon source used for growth. Enzymes of glycolytic and oxidative pathways were detected in cells grown on glucose, glycerol, or pyruvate but enzymes of the Entner–Doudoroff pathway could be detected only in glucose-grown cells. Labeled acetate is utilized by cells cultured on glucose, glycerol, and pyruvate. In all cases more of C1 of acetate was converted to CO2 while incorporation into cellular constituents was maximum from C2 of acetate.

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