Document Detail


Tyrosine hydroxylase expression and activity in the rat brain: differential regulation after long-term intermittent or sustained hypoxia.
MedLine Citation:
PMID:  15817718     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Tyrosine hydroxylase, a hypoxia-regulated gene, may be involved in tissue adaptation to hypoxia. Intermittent hypoxia, a characteristic feature of sleep apnea, leads to significant memory deficits, as well as to cortex and hippocampal apoptosis that are absent after sustained hypoxia. To examine the hypothesis that sustained and intermittent hypoxia induce different catecholaminergic responses, changes in tyrosine hydroxylase mRNA, protein expression, and activity were compared in various brain regions of male rats exposed for 6 h, 1 day, 3 days, and 7 days to sustained hypoxia (10% O(2)), intermittent hypoxia (alternating room air and 10% O(2)), or normoxia. Tyrosine hydroxylase activity, measured at 7 days, increased in the cortex as follows: sustained > intermittent > normoxia. Furthermore, activity decreased in the brain stem and was unchanged in other brain regions of sustained hypoxia-exposed rats, as well as in all regions from animals exposed to intermittent hypoxia, suggesting stimulus-specific and heterotopic catecholamine regulation. In the cortex, tyrosine hydroxylase mRNA expression was increased, whereas protein expression remained unchanged. In addition, significant differences in the time course of cortical Ser(40) tyrosine hydroxylase phosphorylation were present in the cortex, suggesting that intermittent and sustained hypoxia-induced enzymatic activity differences are related to different phosphorylation patterns. We conclude that long-term hypoxia induces site-specific changes in tyrosine hydroxylase activity and that intermittent hypoxia elicits reduced tyrosine hydroxylase recruitment and phosphorylation compared with sustained hypoxia. Such changes may not only account for differences in enzyme activity but also suggest that, with differential regional brain susceptibility to hypoxia, recruitment of different mechanisms in response to hypoxia will elicit region-specific modulation of catecholamine response.
Authors:
Evelyne Gozal; Zahoor A Shah; Jean-Marc Pequignot; Jacqueline Pequignot; Leroy R Sachleben; Maria F Czyzyk-Krzeska; Richard C Li; Shang-Z Guo; David Gozal
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, P.H.S.     Date:  2005-04-07
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  99     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-07-15     Completed Date:  2005-09-30     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  642-9     Citation Subset:  IM    
Affiliation:
Kosair Children's Hospital Research Institute, 570 S. Preston Street, Suite 321, Louisville, KY 40202, USA. evelyne.gozal@louisville.edu
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MeSH Terms
Descriptor/Qualifier:
Acute Disease
Adaptation, Physiological
Animals
Anoxia / classification,  metabolism*
Brain / enzymology*
Chronic Disease
Enzyme Activation
Gene Expression Regulation, Enzymologic
Male
Rats
Rats, Sprague-Dawley
Time Factors
Tissue Distribution
Tyrosine 3-Monooxygenase / metabolism*
Grant Support
ID/Acronym/Agency:
HH 66312/HH/HHS; HL 58687/HL/NHLBI NIH HHS; HL 63912/HL/NHLBI NIH HHS; HL 66358/HL/NHLBI NIH HHS; HL 69932/HL/NHLBI NIH HHS; HL 74296/HL/NHLBI NIH HHS; P20 RR 15576/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
EC 1.14.16.2/Tyrosine 3-Monooxygenase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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