Figure 3.

Loss of astrocytic domain organization 1 week after injury. A, Diolistic labeling of a cortical slice from an adult mouse expressing GFP under the hGFAP promoter 1 week after iron injection. Two adjacent GFP-positive astrocytes are labeled with DiI and DiD. Blue, DAPI; white, GFP; green, DiI; red, DiD. Scale bar (SB), 20 μm. B, Diolistic labeling of palisading reactive astrocytes demonstrating loss of the domain organization. Green, DiI; red, DiD; blue, DAPI. SB, 20 μm. C, Quantification of the volume of reactive astrocytes 1 week postinjury (PI) compared with astrocytes from control mice. The volume represents the total area of the astrocytic soma and processes labeled with DiI or DiD in serial sections (n = 20 cells, 7 mice; mean ± SEM; *p < 0.001). D, Quantification of the area of overlap between reactive astrocytes 1 week after injury compared with astrocytes in control mice over 10 μm stacks, and summation of the total length of processes that enter an adjacent cell's domain 1 week after injury compared with control over 10 μm stacks. The area of overlap and the total length of overlapping processes increased 15-fold in epileptic mice (control, n = 30 cells, 7 mice; 1 week after injury, n = 34 cells, 10 mice; mean ± SEM; *p < 0.001). E–H, High-power image of blue box in A of reactive astrocytes 1 week after injury. F, Area of overlap is delineated in gray, the red line is the border of the domain of the red cell, and the green line is the border of the domain of the green cell. G, H, Yellow lines indicate the processes of the cell that enter the domain of the adjacent astrocyte. I–L, Similar analysis in control mouse in which astrocytes are organized in essentially nonoverlapping domains.