Effect of diet and tryptophan on hepatic polyribosomal disaggregation due to actinomycin D.

Abstract

Abstract The effect of prefeeding a complete diet on polyribosomal disaggregation due to actinomycin D and the effect of trytophan on polyribosomal disaggregation after actinomycin D on the livers of rats were investigated. Fasted rats that were treated with actinomycin D showed moderate to marked disaggregation of hepatic polyribosomes after 6–12 hr. In contrast, fed rats, especially those tube-fed shortly prior to actinomycin treatment, showed much less, only minimal, disaggregation of hepatic polyribosomes. The effect of prefeeding could be observed with a protein-free diet and was not related to altered absorption of actinomycin or changes in actinomycin-induced inhibition of RNA synthesis or induction of tryptophan pyrrolase after cortisone. The disaggregation of hepatic polyribosomes in fasted rats after actinomycin could be returned toward normal, becoming reaggregated, by the administration of tryptophan but not by other single amino acids. Tryptophan did not influence the degree of inhibition of hepatic RNA synthesis due to actinomycin.