Effect of tryptophan or phenobarbital administration on hepatic polyribosomes and protein synthesis in rats force-fed a complete or threonine-devoid diet.
Young rats were force-fed a complete or threonine-devoid diet for 3 days. Prior to killing on the fourth morning rats of each group were treated with l-tryptophan (30 mg/100 g body weight) 2 hours before killing or with sodium phenobarbital (8 mg/100 g body weight) 14 hours before killing. Rats force-fed the threonine-devoid diet revealed increased aggregation of polyribosomes (sucrose density gradient analyses) and increased protein synthesis (in vitro [14C]leucine incorporation into protein) in the livers in comparison to that in the livers of rats force-fed the complete diet. Plasma total tryptophan levels were decreased and plasma free tryptophan as a percentage of total plasma tryptophan was increased in rats force-fed the threonine-devoid diet for 3 days. Administration of tryptophan or of phenobarbital stimulated polyribosomal aggregation and in vitro protein synthesis of the livers of rats force-fed the complete or the threonine-devoid diet. These stimulatory effects incuded by tryptophan or phenobarbital were most marked in rats force-fed the threonine-devoid diet. Hepatic tryptophan pyrrolase activity was stimulated to similar degrees following the administration of tryptophan to rats force-fed the complete or the threonine-devoid diet.
D000818:Animals; D004032:Diet; D005260:Female; D007930:Leucine / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology*; D011132:Polyribosomes / Q000187:drug effects; D014176:Protein Biosynthesis; D051381:Rats; D013347:Subcellular Fractions; D013912:Threonine / Q000172:deficiency*; D014364:Tryptophan / Q000097:blood / Q000494:pharmacology*; D014366:Tryptophan Oxygenase / Q000378:metabolism
D013912:Threonine; D014364:Tryptophan; D014366:Tryptophan Oxygenase; D007930:Leucine; D010634:Phenobarbital