Document Detail


Tyrosine promotes oxidative stress in cerebral cortex of young rats.
MedLine Citation:
PMID:  18602789     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Tyrosine accumulates in inborn errors of tyrosine catabolism, especially in tyrosinemia type II, where tyrosine levels are highly elevated in tissues and physiological fluids of affected patients. In tyrosinemia type II, high levels of tyrosine are correlated with eyes, skin and central nervous system disturbances. Considering that the mechanisms of brain damage in these disorders are poorly known, in the present study, we investigated whether oxidative stress is elicited by l-tyrosine in cerebral cortex homogenates of 14-day-old Wistar rats. The in vitro effect of 0.1-4.0mM l-tyrosine was studied on the following oxidative stress parameters: total radical-trapping antioxidant potential (TRAP), total antioxidant reactivity (TAR), ascorbic acid content, reduced glutathione (GSH) content, spontaneous chemiluminescence, thiobarbituric acid-reactive substances (TBA-RS), thiol-disulfide redox state (SH/SS ratio), protein carbonyl content, formation of DNA-protein cross-links, and the activities of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glucose-6-phosphate dehydrogenase (G6PDH). TRAP, TAR, ascorbic acid content, SH/SS ratio and CAT activity were significantly diminished, while formation of DNA-protein cross-link was significantly enhanced by l-tyrosine in vitro. In contrast, l-tyrosine did not affect the other parameters of oxidative stress evaluated. These results indicate that l-tyrosine decreases enzymatic and non-enzymatic antioxidant defenses, changes the redox state and stimulates DNA damage in cerebral cortex of young rats in vitro. This suggests that oxidative stress may represent a pathophysiological mechanism in tyrosinemic patients, in which this amino acid accumulates.
Authors:
Angela M Sgaravatti; Bethânia A Vargas; Bernardo R Zandoná; Kátia B Deckmann; Francieli J Rockenbach; Tarsila B Moraes; José M Monserrat; Mirian B Sgarbi; Carolina D Pederzolli; Angela T S Wyse; Clóvis M D Wannmacher; Moacir Wajner; Carlos Severo Dutra-Filho
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-05-28
Journal Detail:
Title:  International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience     Volume:  26     ISSN:  0736-5748     ISO Abbreviation:  Int. J. Dev. Neurosci.     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-07-21     Completed Date:  2008-11-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8401784     Medline TA:  Int J Dev Neurosci     Country:  England    
Other Details:
Languages:  eng     Pagination:  551-9     Citation Subset:  IM    
Affiliation:
Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
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MeSH Terms
Descriptor/Qualifier:
Analysis of Variance
Animals
Animals, Newborn
Antioxidants / metabolism
Ascorbic Acid / metabolism
Catalase
Cerebral Cortex / physiology*
Dose-Response Relationship, Drug
Glucosephosphate Dehydrogenase / metabolism
Glutathione / metabolism
Glutathione Peroxidase / metabolism
Lipid Peroxidation / drug effects
Oxidative Stress / drug effects*
Rats
Rats, Wistar
Sulfhydryl Compounds / metabolism
Superoxide Dismutase / metabolism
Thiobarbituric Acid Reactive Substances
Tyrosine / pharmacology*
Chemical
Reg. No./Substance:
0/Antioxidants; 0/Sulfhydryl Compounds; 0/Thiobarbituric Acid Reactive Substances; 50-81-7/Ascorbic Acid; 55520-40-6/Tyrosine; 70-18-8/Glutathione; EC 1.1.1.49/Glucosephosphate Dehydrogenase; EC 1.11.1.6/Catalase; EC 1.11.1.9/Glutathione Peroxidase; EC 1.15.1.1/Superoxide Dismutase

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