The effect of dietary protein and sulfur amino acids on hepatic glutathione concentration and glutathione-dependent enzyme activities in the rat.
Hepatic glutathione concentration and glutathione-dependent enzymes, glutathione S-transferase, glutathione peroxidase, and glutathione reductase, are important for protection against toxic compounds. Rats were fed diets containing 4, 7.5, 15, or 45% protein for 2 weeks. Glutathione and cysteine concentrations in rats fed the 4 and 7.5% protein diets were significantly lower (p less than 0.05) than in rats fed the 15 and 45% protein diets. Glutathione S-transferase activity increased with increasing dietary protein. Glutathione peroxidase activity was significantly lower (p less than 0.05) in rats fed 4 and 7.5% protein compared with rats fed 15 and 45% protein, whereas the activity of glutathione reductase was higher in rats fed 4 and 7.5% protein then in rats fed 15 or 45% protein. Dietary sulfur amino acids alone could account for the increase in glutathione concentration resulting from the increase in dietary protein from 7.5 to 15%. The limited availability of glutathione in animals fed the low protein diets could reduce the potential for detoxification of xenobiotics.
Bauman
P F
PF
Department of Nutritional Sciences, College of Biological Science, University of Guelph, Ont., Canada.
Smith
T K
TK
Bray
T M
TM
D000603:Amino Acids, Sulfur / Q000494:pharmacology*; D000818:Animals; D003545:Cysteine / Q000378:metabolism; D004044:Dietary Proteins / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D008658:Inactivation, Metabolic; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D000603:Amino Acids, Sulfur; D004044:Dietary Proteins; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005982:Glutathione Transferase; D005978:Glutathione; D003545:Cysteine