Cranial irradiation is used routinely for the treatment of nearly all brain tumors, but may lead to progressive and debilitating impairments of cognitive function. To determine whether changes in dendritic architecture might underlie the neurocognitive sequelae found after irradiation, the authors of this study investigated the impact of cranial irradiation (1 and 10 Gy) on a range of micromorphometric parameters in mice 10 and 30 days following exposure.
They found significant reductions in dendritic complexity, where dendritic branching, length, and area were routinely reduced (more than 50%) in a dose-dependent manner. At these same doses and times they found significant reductions in the number (20-35%) and density (40-70%) of dendritic spines on hippocampal neurons of the dentate gyrus. Immature filopodia showed the greatest sensitivity to irradiation compared with more mature spines.
Dose-responsive changes in dendritic complexity, synaptic protein levels, spine density and morphology induced in hippocampal neurons by irradiation could persist for at least 1 month, and were observed to resemble changes found in many neurodegenerative conditions.
Parihar VK and Limoli CL: Cranial irradiation compromises neuronal architecture in the hippocampus. PNAS 110(31): 12822-12827 (2013).
