title: Effect of dietary methionine on tissue selenium and glutathione peroxidase (EC 1.11.1.9) activity in rats given selenomethionine.
abstract: 1. The effect of dietary methionine on the utilization of selenium from dietary selenomethionine [( Se]Met) for tissue Se deposition and for glutathione peroxidase (EC 1.11.1.9; GSH-Px) synthesis was studied in male weanling rats. 2. When rats were given 0.5 mg Se as [Se]Met/kg diet supplemented with 0, 4 or 9 g methionine/kg, Se in plasma, erythrocytes, liver and muscle increased significantly over the 20 d period for all methionine-treatment groups. The increases in erythrocyte and muscle Se, however, were significantly higher in rats fed on the methionine-deficient diet compared with the methionine-supplemented diets. 3. In contrast to the increases in tissue Se, GSH-Px activity in liver, plasma and muscle decreased in methionine-deficient rats given 0.5 mg Se as [Se]Met/kg whereas GSH-Px activity was maintained or increased in rats supplemented with methionine. 4. The percentage of tissue Se associated with GSH-Px was calculated from the measured Se concentration and GSH-Px activity. A significantly lower percentage of Se was associated with GSH-Px in methionine-deficient rats compared with methionine-supplemented rats. 5. These results show that Se from dietary [Se]Met is preferentially incorporated into body proteins rather than used for GSH-Px synthesis when methionine is limiting in the diet. 6. These results further suggest that [Se]Met might not be the optimum Se compound to use for Se supplementation because metabolism of dietary [Se]Met to a biochemically active form, such as GSH-Px, was impaired when [Se]Met was provided in diets low in methionine.
authors.affiliation: Department of Nutrition and Food Science, University of Arizona, Tucson 85721.
authors.forename: I H
authors.initials: IH
authors.lastname: Waschulewski
authors.forename: R A
authors.initials: RA
authors.lastname: Sunde
mesh_terms: D000818:Animals; D001835:Body Weight; D004032:Diet; D005979:Glutathione Peroxidase / Q000097:blood / Q000378:metabolism*; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D009132:Muscles / Q000378:metabolism; D009929:Organ Size; D051381:Rats; D012643:Selenium / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics*; D012645:Selenomethionine / Q000493:pharmacokinetics*
chemical_list: D012645:Selenomethionine; D008715:Methionine; D005979:Glutathione Peroxidase; D012643:Selenium