scholarly journals Energy Metabolism in Neural Tissues in vivo at Rest and in Functionally Altered States

Author(s):  
Louis Sokoloff
Author(s):  
W.A. Jacob ◽  
R. Hertsens ◽  
A. Van Bogaert ◽  
M. De Smet

In the past most studies of the control of energy metabolism focus on the role of the phosphorylation potential ATP/ADP.Pi on the regulation of respiration. Studies using NMR techniques have demonstrated that the concentrations of these compounds for oxidation phosphorylation do not change appreciably throughout the cardiac cycle and during increases in cardiac work. Hence regulation of energy production by calcium ions, present in the mitochondrial matrix, has been the object of a number of recent studies.Three exclusively intramitochondnal dehydrogenases are key enzymes for the regulation of oxidative metabolism. They are activated by calcium ions in the low micromolar range. Since, however, earlier estimates of the intramitochondnal calcium, based on equilibrium thermodynamic considerations, were in the millimolar range, a physiological correlation was not evident. The introduction of calcium-sensitive probes fura-2 and indo-1 made monitoring of free calcium during changing energy metabolism possible. These studies were performed on isolated mitochondria and extrapolation to the in vivo situation is more or less speculative.


2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A778-A778
Author(s):  
Minhyuk Yun ◽  
Goo-Young Kim ◽  
Sang Woo Jo ◽  
Changhoon In ◽  
Gyu-Young Moon ◽  
...  

BackgroundNAD(P)H-quinone oxidoreductase 1 (NQO1) is a cytosolic two-electron oxidoreductase overexpressed in many types of cancers, including breast cancer, pancreatic cancer, colorectal cancer, cholangiocarcinoma, uterine cervical cancer, melanoma, and lung cancer.1Up-regulation of NQO1 protects cells from oxidative stress and various cytotoxic quinones and is associated with late clinical stage, poor prognosis and lymph node metastasis.2 3 NQO1 increases stability of HIF-1α protein, which has been implicated in survival, proliferation, and malignance of cancer.1 Therefore, accumulating evidences suggest NQO1 as a promising therapeutic target for cancer. Accordingly, we have characterized the effect of a novel synthetic NQO1 substrate SBSC-S3001, and demonstrated its selective cytotoxic effects in cancer cells with high expression of NQO1.MethodsIn vitro cytotoxicity was determined by sulforhodamine B (SRB) assay in cancer cells with high NQO1 expression and CRISPR-mediated NQO1 knockout cells. The effect of SBSC-S3001 on the energy metabolism pathway was evaluated by western blot analysis of metabolism associated proteins from NQO1-overexpressed cancer cells treated with the compound for 24 hours. In vivo anti-tumor activity was evaluated in MC38 syngeneic and DLD-1 orthotopic mice models.ResultsSBSC-S3001 exhibited selective cytotoxicity in cancer cells with high expression of NQO1 in a dose-dependent manner. The cytotoxicity was observed in both normoxia and hypoxia conditions, correlating with the energy metabolism, mitochondrial biogenesis, and cancer proliferative pathways. Also, stronger cytotoxicity was observed in NQO1-overexpressed cancer cells treated with SBSC-S3001 compared to beta-lapachone and analogue treatment.4 When evaluated in vivo, SBSC-S3001 effectively inhibited the growth of syngeneic and orthotopic tumors when administered as a monotherapy. SBSC-S3001 treatment associated with reduction in key enzymes of the glycolytic pathway (LDHa and GAPDH) and HIF-1α and increase in levels of mitochondrial oxidative phosphorylation (OXPHOS) complex.ConclusionsTreatment of SBSC-S3001, a novel, NQO1-specific substrate reduces HIF-1α and key enzymes associated with glycolysis and suppresses the growth of tumors overexpressing NQO1. Further characterization of SBSC-S3001 as a novel metabolic anti-cancer agent for cancers with NQO1 overexpression is warranted.Ethics ApprovalThe study was approved by Samyang Biopharmaceuticals Institution’s Ethics Board, approval number SYAU2031.ReferencesOh ET, Kim JW, Kim JMet. al., NQO1 inhibits proteasome-mediated degradation of HIF-1α. Nat Commun 2016; 14:13593.Ma, Y. et al. NQO1 overexpression is associated with poor prognosis in squamous cell carcinoma of the uterine cervix. BMC Cancer 2014;14: 414Yang, Y. et al. Clinical implications of high NQO1 expression in breast cancers. J. Exp. Clin. Cancer Res 2014;33:144.Yang Y, Zhou X, Xu M, et al., β-lapachone suppresses tumour progression by inhibiting epithelial-to-mesenchymal transition in NQO1-positive breast cancers. Sci Rep 2017;7:2681.


1997 ◽  
Vol 320 (2-3) ◽  
pp. 111-119 ◽  
Author(s):  
Gail D Zeevalk ◽  
Lawerence Manzino ◽  
James Hoppe ◽  
Patricia Sonsalla

1987 ◽  
Vol 7 (5) ◽  
pp. 557-562 ◽  
Author(s):  
S. Komatsumoto ◽  
S. Nioka ◽  
J. H. Greenberg ◽  
K. Yoshizaki ◽  
V. H. Subramanian ◽  
...  

The energy metabolism of the brain has been measured in a middle cerebral artery (MCA) occlusion model in the cat utilizing 31P-nuclear magnetic resonance (NMR). 31P-NMR spectra were serially obtained during 2 h of ischemia and a subsequent 4-h recovery period. The ratio of creatine phosphate (PCr) to inorganic phosphate (Pi) (PCr/Pi) showed a precipitous decrease in parallel with changes in electroencephalographic (EEG) amplitude in severe strokes during ischemia as well as during recirculation. Animals with mild strokes, as determined by EEG criteria, exhibited a much smaller decrease in PCr/Pi during ischemia. In the severe strokes, there was a splitting and significant shift of the Pi peak immediately after occlusion. In addition, the shifted Pi peak rapidly increased and remained elevated throughout the study. In the mild strokes, Pi also increased, but not as markedly. Intracellular pH determination by chemical shift of the Pi peak revealed a decrease from 7.1 to 6.2–6.3 during ischemia and the subsequent recovery period in the animals with severe strokes, whereas the pH in the animals with mild strokes did not show a significant change. A gradual decrease in adenosine triphosphate (ATP) to 57–79% of the control was exhibited in severely stroked animals during both the ischemia and the recovery period, whereas there was no change in ATP in the mild stroked animals. These results suggest that the dynamic process of pathophysiological changes in an MCA occlusion model in the cat leads to significant differences in cerebral metabolism between animals with mild and severe strokes.


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