A Time Study on the Effect of Cortisol on the Incorporation of Thymidine-2-14C Into Nucleic Acids of Mouse Lymphatic Tissue

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Abstract
CBA mice 10-14 weeks of age were adren-alectomized. Twenty -four hr. later the control animals were injected with a 0.02% carrier solution of carboxymethyl cellulose in saline and the treated animals were injected with 1 mg cortisol acetate in saline. The mice were then injected with thymidine-2-Cl4 at different tie intervals (i.e., 7, 15, 30, 60, 120, 180, 240 and 360 min). Thirty min. later they were sacrificed and their spleens, thymi and lymph nodes were removedand weighed. These lymphatic tissues were extracted for nucleic acids. The data from the spleen showed statistically significant decreases in mg organ weight/ 100 g body weight at 120 and 360 min. after treatment. There were no significant changes in the total amounts of DNA and RNA, total amount of thymidine-2-C14 incorporated (total dpm) and DNA synthesis expressed as dpm/mg DNA at any time intervals following cortisol treatment. There were no statistically significant decreases in lymph node weights following treatment with cortisol. There was, however, a statistically significant decrease in mg thymi/100 g body weight at 360 min. post treatment. No significant differences in total amounts of DNA or RNA were found in the lymph nodes or thymi. There were statistically significant decreases in the incorporation of thymidine-2-C14 (total dpm into DNA) in these 2 tissues after cortisol treatment. The decrease in thymidine-2-C14 incorporation first appeared at 120 min. and continued to decrease until the end of the experimental period.