title: Effect of dietary protein deficiency and L-2-oxothiazolidine-4-carboxylate on the diurnal rhythm of hepatic glutathione in the rat.
abstract: Maximizing hepatic glutathione (GSH) concentration may provide greater protection against toxic compounds. A dietary supplement of L-2-oxothiazolidine-4-carboxylate (OTC), a stable derivative of cysteine, increased hepatic GSH in rats fed for 2 wk a diet deficient in protein (7.5%) but not in rats fed a diet adequate in protein (15%). Experiment 2 determined whether a dietary supplement of OTC could maintain the maximum GSH concentration over 24 h. Rats acclimatized for 5 d to a 7.5% protein diet and then fed a 7.5% protein diet supplemented with either 2.5 mmol OTC or cysteine-HCl (CYS)/100 g diet had a more rapid increase in hepatic GSH (4 and 8 h after beginning of feeding, P less than 0.05) than did rats fed an unsupplemented 7.5% protein diet. This response was not due simply to the greater supply of cysteine for GSH synthesis because supplementing the 15% protein diet with OTC or CYS had no effect on the hepatic GSH of rats acclimatized to a 15% protein diet. In experiment 3, rats acclimatized to the 7.5% protein diet had a more rapid rate of increase in hepatic GSH concentration in response to feeding than did rats acclimatized to a 15% protein diet, regardless of which diet they were fed during the 24-h period. It was concluded that in addition to cysteine availability, previous dietary protein status plays a key role in the regulation of the feeding-induced diurnal rhythm of hepatic GSH concentration in rats.
authors.affiliation: Department of Nutritional Sciences, College of Biological Science, University of Guelph, Ontario, Canada.
authors.forename: P F
authors.initials: PF
authors.lastname: Bauman
authors.forename: T K
authors.initials: TK
authors.lastname: Smith
authors.forename: T M
authors.initials: TM
authors.lastname: Bray
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002940:Circadian Rhythm / Q000187:drug effects*; D003545:Cysteine / Q000008:administration & dosage*; D004032:Diet; D005978:Glutathione / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D011488:Protein Deficiency / Q000150:complications*; D011761:Pyrrolidonecarboxylic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D013844:Thiazoles / Q000008:administration & dosage* / Q000494:pharmacology; D053778:Thiazolidines; D013997:Time Factors
chemical_list: D013844:Thiazoles; D053778:Thiazolidines; D005978:Glutathione; D003545:Cysteine; D011761:Pyrrolidonecarboxylic Acid; C029536:2-oxothiazolidine-4-carboxylic acid