Superoxide dismutase in fetal rat cerebrum X-irradiated in utero

The superoxide dismutase (SOD) activity in fetal rat cerebrum was studied on gestational days (gd) 19 and 21 after X-irradiation with 100R on gd 13 or no X-irradiation. Fetuses X-irradiated on gd 13 showed marked microcephalus on gd 19 and 21. Most of the SOD activity was found in the crude mitochondrial fraction in both groups and most of the SOD was Cu,Zn-SOD. The SOD activity increased about two times from gd 19 to 21. The mean SOD activity of the fetal rat cerebrum X-irradiated with 100R showed no significant differences compared to that of the control group with Student's t test. But the activities in the irradiated group were widely distributed with a large standard deviation and so the chi-square test showed a significant difference in SOD activity between the two groups on gd 19. The SOD activity of adult rat cerebrum 6 and 8 days after X-irradiation with 100R was increased compared to that 3 days after X-irradiation. It was suspected that X-irradiation in utero may have some lasting effect on the SOD activity in fetal rat cerebrum.