Cysteamine protection against lethal and growth-inhibiting effects of prenatal X and gamma irradiation^†

Exposure of pregnant rats to gamma radiation on day 16 of gestation produced nearly double the number of neo- and postnatal offspring deaths as did X irradiation. Dose level (185 r), dose rate (10–12 r/minute), and distance from the source were the same in both groups. Cysteamine given prenatally prior to either gamma or X irradiation significantly decreased mortality. In the gamma-irradiated group the mortality rate remained significantly higher than in the control group, but in the X-irradiated group it was reduced to the control level by pretreatment with cysteamine. Cysteamine given to pregnant rats immediately following gamma irradiation had no effect on offspring mortality.