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17 beta-Estradiol (E2) and progesterone were tested in vitro for their ability to act as anti-glucocorticoids in thymus and spleen cell cultures of ovariectomized female Lewis rats. Initially, the immunosuppressive effect of corticosterone was verified and both sex steroids were also found to inhibit mitogenic, antigenic and allogeneic lymphoblast transformation although at concentrations higher than those for corticosterone. The suppressive activities were stronger in thymocyte than splenocyte cultures. On the other side, E2 significantly enhanced lymphoblast transformation at concentrations of 10(-9) to 10(-7) mol per litre while progesterone had only moderately increasing effects. Combination of corticosterone with progesterone or both sex steroids resulted in significantly elevated 3Tdr incorporation of mitogen-stimulated thymocytes compared to cultures incubated with corticosterone alone while in splenocyte cultures only the mixed lymphocyte reaction showed similar effects. No synergy between E2 and progesterone in counteracting corticosterone-induced inhibition of lymphocyte proliferation has been observed. In conclusion, corticosterone, E2 and progesterone showed a dose-dependent influence on lymphoblast transformation of thymocytes and splenocytes and progesterone had opposite effects on corticosterone-induced suppression of blastogenesis in rat lymphocytes, especially in thymocytes.

The clone Fu 5 a of the Reuber Hepatoma cell line was incubated with corticosterone for 48 hours. The incorporation of labelled thymidine into DNA was inhibited to 10%. After this time corticosterone was removed from the medium. The DNA-synthesis increased for ten hours, the maximum was sixteen times higher than in the controls. The conclusion drawn was that corticosterone is able to block liver cells in a part of G1 phase of the cell cycle, so that the cells become synchronous.

Growing male Albino rats were adrenalectomized and then treated with corticosterone in an attempt to determine the activity of amino transferases (GPT and GOT) in the liver and in the mucosa of the small intestine over a period during which the animals received dietary proteins of varying quality. However, statistically significant differences in the enzyme activity were established for only those groups in which the animals exhibited differences in the functional state of the adrenal cortex. Differences due to changes in the quality of the dietary protein were not observed. From this was concluded that the activity of the amino transferases in the tissues is largely dependent on the action of corticosteroids.