Post-Irradiation Castration of the Male and Enhanced Survival. ∗

Summary and conclusions

1. Male mice of the ICR and CF1 strains were X-irradiated to the LD/50/30 range and some were castrated in order to determine whether the loss of testosterone might alter survival. 2. In both strains, post-irradiation castration (within 30 minutes) did indeed increase statistically the survival of the mice. 3. A delay in castration of 24 hours after irradiation (of the CF1 males) increased survival chances, and estradiol (at that time) further improved survival probability. However, estradiol benzoate given immediately after X-irradiation and castration had an unfavorable effect. 4. It is suggested that the mechanism of effect of castration may be in the encouragement of lymphocyte recovery, thus reducing the usual effects of lymphopenia attendant upon X-irradiation. 5. Since the survival improvement by post-irradiation castration is statistically significant, but amounts to only about 30%, its efficacy lies near the LD/100/30 range, and not higher. Possibly in combination with bone marrow the benefits would be additive, or even synergistic.