Concerning the effects of corticosteroids on lymphoid tissue, there have been carried out with mainly morphological and histological methods. It is wellknown that the lymphoid tissue falls into atrophy caused by the administration of corticosteroids.
In 1963 Akasu and Tateno observed in their experiments on rat ascites hepatoma that the lymphnodes, treated with cortisone, seldom suffered from the metastasis of ascites hepatoma, and they assumed the possibility of preventability of metastasis of cancer in man.
The purpose of the present study is to investigate the changes induced by cortisone, by means of the determination of the nucleic acid contents in the lymphnodes.
Female rats weighing between 80 and 120 g. were used throughout this experiment and they were divided into four groups. The first group was intended for the control (Group A). The other groups (Group B, C and D) were treated as follows :
Each animal of group B, C and D received 2.5 mg. of cortisone acetate, injected subcutaneously, on each day for 10 days. On the other hand, animal of group A (Control) received 0.1 ml. of physiological salt solution, instead of cortisone, injected similarly. Then 20, ac of
32P solution was subcutaneously injected into each animal, the administration being carried out on the first, third, and fifth day after the final injection of cortisone or salt solution, respectively, for group A and B, C, and D. All the animals of these four groups were sacrificed 6 hours after receiving the isotope.
After the sacrifice of animals, lumbal lymphnodes were excised for the measurement of the nucleic acid contents and the
32P incorporated into the nucleic acids. Throughout this experiment, ribonucleic acids (RNA) were determined by the color reaction of its pentose with orcine and deoxyribonucleic acids (DNA) by the reaction with diphenylamine, after the separation of RNA and DNA by the method based on Schmidt and Thannhauser procedure.
The results of the experiment are summarised as follows :
(1) DNA contents of the lymphnodes decreased remarkably by the treatment with cortisone, and were restored on the fifth day after the final treatment. These changes might be attributed to the destruction of lymphocytes.
(2) Treated RNA contents of the lymphonodes were slightly decreased, and the restoration of the decrease was earlier as compared with those of DNA contents.
(3) The ratio of RNA to DNA contents and the ratio of RNA-
32P to DNA-
32P became elevated by the treatment. The normal value of the latter, however, was observed on the fifth day after the treatment.
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