EFFECTS OF THALIDOMIDE AND CHLORCYCLIZINE ON THE BIOSYNTHESIS OF NUCLEIC ACIDS AND PROTEINS IN FETAL AND MATERNAL TISSUES OF THE RAT

¹ Departments of Pediatrics and Biochemistry, School of Medicine, University of Miami, Miami, Florida

The effects of the teratogens thalidomide and chlorcyclizine on the biosynthesis of nucleic acids and proteins were studied in pregnant rats. Thalidomide administration resulted in the accumulation of the labeled precursors, thymidine and glycine, in the nucleic acids of fetus and maternal tissues, suggesting accelerated biosynthesis of deoxyribonucleic acid and ribonucleic acid. The increase in the accumulation of thymidine was reversed by actinomycin D. Thalidomide had comparatively little effect on the incorporation of precursors into tissue proteins. In contrast, after chlorcyclizine the accumulation of isotopes of thymidine in the fetus was less than in controls. Chlorcyclizine promoted the incorporation of amino acids into the proteins of fetal and maternal tissues. The data suggest a suppression of deoxyribonucleic acid synthesis in the fetus, but a stimulation of the biosynthesis of proteins.