Relative Value of Cysteamine and Cystamine as Radioprotective Agents for Fetal and Adult Mice

¹ From the Radiological Research Laboratory, Columbia University, New York City

The —SH compound cysteamine and its —SS product, cystamine, have been tested as protective agents against x-irradiation death for adult CF₁ mice of both sexes, and also the 15.5–17.5-day fetuses of the same strain. Control fetuses of 15.5–17.5 days rarely survived x-irradiation to 600 r or more while those whose mothers were injected with cysteamine prior to irradiation could tolerate 700-r x-rays and the majority of offspring survived 30 days postparturition. When irradiated fetuses were given foster (normal) mothers at birth, survival was further improved, but only in those whose mothers were given the drug just prior to irradiation. Cystamine also gave protection to the fetuses. Optimum survival of controls exposed at 17.5 days to 700-r x-rays was 19% at 30 days, while those ‘protected’ by cysteamine showed 50% survival and with cystamine, 41% survival. Thus there was definitely fetal ‘protection’ by either drug. Adult males and females of the same strain showed considerable ‘protection’ by either drug, the males increasing survival from 2% to 30% (cystamine) and 34% (cysteamine) while the females showed increased survival value to 56% and 64%, respectively. It is apparent that both of these drugs have protective value for fetal and adult mice of both sexes, when they are exposed to the ld_50/30-day level of x-rays.