IN-UTERO EXPOSURE TO LOW-DOSES OF IONIZING-RADIATION DECELERATES NEURONAL MIGRATION IN THE DEVELOPING RAT-BRAIN

In order to elucidate the possible mechanisms for the effects of low d oses of ionizing radiation on the developing rat cerebral cortex we st udied how neuronal migration can be affected by prenatal in utero irra diation. We have demonstrated an effect of ionizing radiation on neuro nal migration at doses as low as 15 cGy together with a changing patte rn of expression of the neural cell adhesion molecule N-CAM. After a d ose of 15 cGy or more there was a reduction in N-CAM immunoreactivity in the matrix cell zone which became apparent about 24 h after exposur e and after exposure. Normal reactivity exposure to radiation. However , there was no obvious change in the immunoreactivity for L1, MAP2, ta u protein or neurofilament. Our findings suggest the possible role of N-CAM in neuronal migration and also suggest the presence of a thresho ld in terms of the effects of small radiation doses on the developing cerebral cortex.