Effects of Low Dietary Intake of Methionine, Choline and Protein on the Biotransformation of Arsenite in the Rabbit

THE EFFECTS OF SIX WEEKS FEEDING WITH DIETS LOW IN METHIONINE, CHOLINE, METHIONINE AND CHOLINE, OR PROTEINS ON THE BIOTRANSFORMATION AND RETENTION OF 76AS-LABELLED ARSENITE (0.4 MG AS/KG BODY WEIGHT) IN RABBITS HAVE BEEN STUDIED. ALL TEST DIETS CAUSED ADEPRESSION OF THE METHYLATION OF THE ADMINISTRATED ARSENITE, AND A SIGNIFICANTLY DECREASE IN THE URINARY EXCRETION OF 76AS-DIMETHYLARSINIC ACID, THE MAIN METABOLITE OF INORGANIC ARSENIC. THIS GAVE RISE TO AN INCREASED RETENTION OF ARSENIC IN THE TISSUES, AT 3 DAYS AFTER THE ARSENITE ADMINISTRATION MAINLY IN THE LIVER KIDNEYS, LUNGS AND TESTES. THIS EFFECT WAS MOST MARKED IN RABBITS FED A DIET DEPRIVED IN BOTH METHIONINE AND CHOLINE. THE TEST DIETS ALSO CAUSED A SPECIFIC INCREASE OF THE ARSENIC CONCENTRATION IN THE LIVER MICROSOMES, WHICH DOES NOT OCCUR FOLLOWING CHEMICALLY INDUCED DEPRESSION OF THE ARSENIC METHYLATION. THE RESULTS INDICATE THAT SUBJECTS WITH A LOW NUTRITIONAL STATUS, ESPECIALLY LOW PROTEIN INTAKES, HAVE A LOWER CAPACITY OF METHYLATING AND THEREBY DETOXIFYING INORGANIC ARSENIC, WHICH WOULD RENDER THEM MORE SENSITIVE TO ARSENIC EXPOSURE. KEY WORDS: ARSENITE, BIOTRANSFORMATION, METHYLATION, MALNUTRITION, METHIONINE, CHOLINE

MARAFANTE Erminio; 

1995-03-15

JRC4202