Nitric oxide evokes an adaptive response in hypothyroid condition by inhibition of cytochrom c oxidase
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1
I. Beritashvili Institute of Physiology, Georgia
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2
I. Chavchavadze State University, Georgia
Thyroid hormones modulate metabolic efficiency by controlling the coupling of mitochondrial oxidative phosphorylation, and depression of metabolism by hypothyroidism decreases oxidant production and protects tissues against oxidant damage. Thyroid status affects mitochondrial NO synthesis, but the role of nitrative reactions in brain mitochondrial functions is poorly understood. In a various neuropathological conditions, despite its well-documented pro-oxidant functions, NO can be cytoprotective and may prevent oxidative damage of cells. We have analyzed the effect of hypothyroidism on the activities of hippocampal mitochondrial nitric oxide synthase (NOS), aconitase, fumarate hydratase, succinate dehydrogenase, cytochrome c oxidase and hexokinase. Our results have shown that hypothyroidism increases the activity of mitochondrial NOS (MtNOS) and accelerates the rate of oxidation of Cu in cytochrome c oxidase. The activities of both, redox sensitive enzyme – aconitase, as well as redox insensitive enzyme - fumarate hydratase, equally changed in hypothyroid rats, suggesting that the action of NO limited only by the action on cytochrome c oxidase. The oxidation of cytochrome c oxidase was accompanied by acceleration of mitochondrial hexokinase and high correlation between the activity of hexokinase and rates of oxidation of citochrome c oxidase (r=0.95) was found. Our data suggest that NO-dependent respiratory arrest through inhibition of cytochrome c oxidase and compensatory elevation of anaerobic glycolysis represents an adaptive response in hypothyroid conditions.
This study was supported by Georgian National Scientific Foundation (Grant #GNSF/ST08/2-376).
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Cellular neuroscience
Citation:
Narmania
N,
Sepashvili
M,
Barbakadze
T,
Zhuravliova
E and
Mikeladze
DG
(2010). Nitric oxide evokes an adaptive response in hypothyroid condition by inhibition of cytochrom c oxidase.
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00108
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Received:
23 Apr 2010;
Published Online:
23 Apr 2010.
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Correspondence:
Nana Narmania, I. Beritashvili Institute of Physiology, Tbilisi, Georgia, n.narmania@yahoo.com