FLASH-RT did not elevate astrocytic expression of the danger receptor TLR4. Volumetric quantification of confocal z stacks (green, GFAP; red, TLR4, panel A) and 3D reconstruction of GFAP+ surface (green, panel B) co-labeled with TLR4 (red, panel B) showed a significantly elevated total TLR4 and co-labeling with the danger-sensing receptor TLR4 one month after CONV-RT (panels C and D). Data are presented as Mean ± SEM (n = 5–6 animals per group). P values are derived from non-parametric Kruskal-Wallis H test and Mann-Whitney’s comparison between each group as indicated. Scale bar = 5 μm (panels A and B).