Although PPARδ-null mice do not show a radiation-induced microglial response, they may display an astrocytic response. Of note, PPARδ-null mice express increased mRNA levels of GFAP, a marker of astrocytes, compared to WT mice. Additionally, while WBI reduced the number of astrocytes, GFAP+ cells, two months after irradiation in WT mice, there was no apparent decrease in the number of astrocytes in the irradiated PPARδ-null mice. While these findings are preliminary, they do suggest that PPARδ may modulate the radiation response of the astrocyte (unpublished results).
