INFLUENCE OF L-ALANINE ON EFFECTS INDUCED BY L-TRYPTOPHAN ON RAT-LIVER

This study was designed to determine if a nuclear tryptophan receptor- ligand relationship plays a role in the stimulatory effects of L-trypt ophan administration on rat liver. Two compounds, L-alanine and DL-bet a-(1-naphthyl)alanine(beta-NA), which competed for in vitro H-3-trypto phan binding to hepatic nuclei similar to that of L-tryptophan but whi ch when administered alone in vivo did not stimulate hepatic protein s ynthesis as did L-tryptophan, were used ill this study. Rats treated w ith L-alanine or beta-NA together or before L-tryptophan failed to dem onstrate the stimulatory effects in the liver (protein synthesis, nucl ear poly(A)polymerase activity, and nuclear RNA efflux) as observed in rats treated with L-tryptophan alone. The findings indicate that the enhanced hepatic protein synthesis that occurs following the in vivo a dministration of L-tryptophan appears to be related to L-tryptophan's ability to bind to a specific nuclear tryptophan receptor.