Forebrain damage following prenatal exposure to low-dose X-irradiation.
Exposure of fetal rats to X-irradiation on gestational day 15 resulted postnatally in dose-related effects on body weight, growth of forebrain structures, and branching of dendrites of caudate neurons. Rats were followed for 4 months postnatally after 125, 75, 50, or 25 R whole-body irradiation to the dam. Significant decreases in body weight were present at birth after the three high doses and continued as long as 4 months after 125 or 75 R. Decreased thickness of the cerebral cortex and decreased area of the caudate nucleus were also seen. Cortical thickness was reduced by 125 R to half the size of the control cortex and the caudate nucleus to two-thirds of the control. Significant decreases were present to 50 R. Dendritic branching was reduced in caudate neurons by 125 R but not in the basilar dendrites of cortical pyramidal cells. No reduction in number of cortical synapses was seen from electron micrographs of cortical layers 1 or 5. The effect on the cerebral cortex was interpreted as a loss of neurons with retention of branching and synaptogenesis of remaining neurons. In contrast, the caudate nucleus, which develops somewhat before the cerebral cortex, showed effects as a consequence either of direct damage to caudate neurons or of reduced neuropil from reduced afferent input.
D000818:Animals; D001835:Body Weight / Q000528:radiation effects; D001921:Brain / Q000254:growth & development; D001927:Brain Diseases / Q000473:pathology* / Q000503:physiopathology; D002421:Caudate Nucleus / Q000528:radiation effects*; D002540:Cerebral Cortex / Q000528:radiation effects*; D005260:Female; D006128:Growth / Q000528:radiation effects; D011247:Pregnancy; D011833:Radiation Injuries, Experimental / Q000473:pathology* / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000528:radiation effects