Dietary deficiency of cystine and methionine in rats alters thiol homeostasis required for cyanide detoxification.

TitleDietary deficiency of cystine and methionine in rats alters thiol homeostasis required for cyanide detoxification.
Publication TypeJournal Article
Year of Publication1998
AuthorsTor-Agbidye J, Palmer VS, Sabri MI, Craig AM, Blythe LL, Spencer PS
JournalJournal of toxicology and environmental health. Part A
Volume55
Issue8
Pagination583-95
Date Published1998 Dec 25
ISSN1528-7394
KeywordsAnimals, Cyanides, Cystine, Female, Homeostasis, Metabolic Detoxication, Drug, Methionine, Rats, Rats, Sprague-Dawley, Sulfates, Sulfhydryl Compounds, Thiocyanates
Abstract

Nutritional status is an important factor in modulating the metabolic fate of xenobiotics. Sulfur amino acid (SAA) deficiency has been proposed as a risk factor for human neurological diseases among protein-poor populations subsisting on the cyanophoric plant cassava. Female Sprague-Dawley rats were used to develop and define a model of SAA deficiency for use in future studies examining cassava-related neurotoxicity. Rats were kept in metabolic cages for 7-21 d and fed a balanced diet (BD) of known composition or a comparable diet selectively deficient in methionine and cystine (SAA-free diet). Animals fed the SAA-free diet failed to thrive, lost body weight, excreted porphyrinic materials, and showed a steep and persistent reduction of urinary inorganic sulfate. In contrast, animals on the BD gained body weight and maintained baseline output of urinary inorganic sulfate. Urinary thiocyanate excretion did not differ between groups, but plasma thiocyanate concentrations reached double that in SAA-deficient rats. Increased plasma thiocyanate suggests mobilization of sulfur amino acids from endogenous sources. Liver glutathione and blood cyanide concentrations were similar in animals on the BD and the SAA-deficient diet. In summary, a diet free of methionine and cystine results in increased retention of inorganic sulfur as thiocyanate and a near absence of inorganic sulfur excretion in urine.

Alternate JournalJ. Toxicol. Environ. Health Part A