Effect of the initiation and duration of physical exercise on the deleterious effects induced by ionizing radiation on the brain.

Radiotherapy can damage healthy brain tissue, leading to cognitive deficits. Physical exercise enhances neurogenesis and synaptic plasticity, improving cognitive functions like memory and learning. This study evaluated aerobic exercise's effect on endothelial marker gene expression and memory in cranially irradiated mice. In total, 144 male Swiss mice were divided into sedentary control (SC), sedentary irradiated (SI), exercise control (EC), and irradiated exercise (EI) groups. The EI groups underwent treadmill training in three conditions: 3-months post-irradiation, 1-month pre-irradiation, and 1- month post-irradiation. Ninety days after irradiation, memory was tested using the open- field and object location memory tests. RT-qPCR analyzed hippocampal expression of VEGF-A, eNOS, and vWF. No differences were found in the open-field test, but sedentary irradiated mice showed impaired memory in the object location task. Treadmill training restored memory, especially in the 3-month post-irradiation group. Irradiation increased vWF expression, which physical exercise mitigated. Physical activity also increased VEGF-A and eNOS expression in irradiated mice. These findings suggest that post-irradiation exercise mitigates memory impairment and may influence vascular changes in the brain.