Influence of dietary tryptophan on the induction of gamma-glutamyltranspeptidase-positive foci in the livers of rats treated with hepatocarcinogen.
The ingestion of an elevated level (2%) of L-tryptophan (TRP) in a purified diet was investigated to determine whether it would influence the induction of gamma-glutamyltranspeptidase (GGT)-positive foci in the livers of rats exposed to a hepatocarcinogen. Subtotal hepatectomies were performed, and 18 h later, the rats were given injections i.p. of diethylnitrosamine (30 mg/kg). Ten days later, groups of male rats were placed on choline-supplemented (CS), CS + TRP, choline-deficient (CD), or CD + TRP diets for 10 wk. In two separate experiments, the rats fed the CS + TRP diet or the CD diet developed more and larger GGT + foci than did rats fed the CS diet. Rats fed the CD + TRP diet revealed similar changes to those found in rats fed the CD diet. The liver weights of the rats fed the CD or the CD + TRP diet were greater than those of rats fed the CS or the CS + TRP diet. Hepatic GGT activity was somewhat elevated in rats fed the CS + TRP diet and markedly elevated in rats fed the CD or the CD + TRP diet. Hepatic ornithine decarboxylase activity was increased in rats fed the CD + TRP diet. The results suggest that increased dietary tryptophan has a promoting effect on liver carcinogenesis as measured by the induction of GGT + foci in the livers of rats exposed to diethylnitrosamine. A potentiating effect by tryptophan was not observed in the livers of rats fed a CD diet.
Sidransky
H
H
Garrett
C T
CT
Murty
C N
CN
Verney
E
E
Robinson
E S
ES
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002796:Choline Deficiency / Q000378:metabolism; D004032:Diet; D004790:Enzyme Induction; D008099:Liver / Q000201:enzymology*; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced* / Q000201:enzymology; D008297:Male; D009955:Ornithine Decarboxylase / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014364:Tryptophan / Q000494:pharmacology*; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
D000596:Amino Acids; D014364:Tryptophan; D005723:gamma-Glutamyltransferase; D009955:Ornithine Decarboxylase