AUTORADIOGRAPHIC STUDIES ON THE DISTRIBUTION OF ¹⁴C-1, 2-DIMETHYLHYDRAZINE DIHYDROCHLORIDE AND ITS EFFECT ON DNA SYNTHESIS IN SWISS MICE

Abstract

Light microscopic autoradiographic studies were made on the distribution of ¹⁴C-1, 2-dimethylhydrazine dihydrochloride in Swiss mice and on the effect of 1, 2-dimethylhydrazine dihydrochloride on DNA synthesis, using the ³H-thymidine incorporation technique. In the first study, ¹⁴C-1, 2-dimethylhydrazine dihydrochloride was administered subcutaneously or orally. Large amount of silver grains were found in hepatocytes and substantially lower amount of silver grains observed in the endothelial cells and epithelial cells of colon. In the second study, repeated injections or oral administrations of 1, 2-dimethylhydrazine dihydrochloride were given to mice which subsequently received ³H-thymidine treatment. A somewhat higher amount of thymidine incorporation in DNA was noted in the epithelial cells of the colon of subcutaneously and orally treated mice at two occasions and a substantially higher amount in the endothelial cells of blood vessels in liver of mice treated by both routes than in the corresponding controls. In three instances, however, the amount of incorporation decreased; in the hepatocytes and endothelium at 1 week and 24hr, respectively, after oral treatment, and in the epithelium of the colon at 3 months, after subcutaneous administration.
In the mice treated with 1, 2-dimethylhydrazine dihydrochloride, a significantly high amount of ³H-thymidine incorporation was observed in the endothelial cells of blood vessel in liver from which tumors later arose, and somewhat high in the hepatocytes in which tumor did not develop. In the epithelial cells of colon, no apparent relationship can be seen between these events. No association was seen in the distribution of ¹⁴C-1, 2-dimethylhydrazine dihydrochloride and tumor development in various cells.