Molecular Pharmacology, Vol 19, 103-108, Copyright © 1981 by the American Society for Pharmacology and Experimental Therapeutics

The Effect of D-Galactosamine and Actinomycin D on Polysomes and Messenger RNA Levels in Rat Liver

¹ Biochemisches Institut, Universität Freiburg, 7800 Freiburg in Breisgau, and Institut für Experimentelle Pathologie, Deutsches Krebsforschungszentrum, 6900 Heidelberg, Germany

The amount of polysomes isolated from rat liver 6 hr after D-galactosamine administration decreased to approximately 50% of that isolated from livers of control rats. This decrease was not found after the administration of actinomycin D, although RNA synthesis was inhibited to a similar extent. No corresponding decrease in total hepatic mRNA after D-galactosamine injection was found upon translation in vitro in a reticulocyte cell-free system. The albumin mRNA level measured either by translation in vitro and immunoprecipitation or by hybridization to a specific complementary DNA probe was also unchanged after D-galactosamine administration. It is concluded that the disaggregation of polysomes observed after D-galactosamine administration cannot be due to alterations in mRNA but may rather be due to the modification or loss of as yet unknown molecules involved in the binding of ribosomes to mRNA.

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ACKNOWLEDGMENTS The authors would like to thank Prof. Dr. K. Decker and Prof. Dr. W. Reutter for their interest in this work, many helpful discussions, and the critical reading of the manuscript. We also thank H.-P. Henninger, Freiburg, for his help with the high-pressure liquid chromatography analysis.