Figure 1.

Expression of phosphorylated signal transducer and activator of transcription 3 (pStat3) after focal demyelination in spinal cord white matter is reduced in glial fibrillary acidic protein (GFAP) promoter-controlled conditional Stat3 knockout mice. A: Control and mutant animals were injected with lysolecithin to create a focal demyelination lesion. B and C: The quantification of the total numbers of pStat3⁺ (B) and pStat3/Gfap double-positive (C) cells in control and GFAP-STAT3-CKO lesions. D–I: Immunostaining of lesioned ventral spinal cord white matter at 14 days after lesion (dpl). D and G: Merged immunostaining for phosphorylated Stat3 (pStat3), and the nuclear dye Hoechst 33342. The dotted line marks the border of the demyelinated area, as demarcated by increased cellularity shown by Hoechst staining (inset in D). E and H: Co-labeling with pStat3 and astrocyte marker Gfap; boxed area in each image is magnified in panels F and I, respectively. J and K: Representative images show colocalization of an alternative astrocyte marker Aldh1l1 and pStat3 in demyelinated areas at 14 dpl, in control (J) and GFAP-STAT3-CKO (K) animals. L–O: Quantification is shown. pSTAT3 also is expressed in other types of cells, including CD11b⁺ macrophages/microglia (M and N) and Olig2⁺ oligodendrocyte lineage cells (O) within lesions. Means ± SEM are shown. Arrowheads (F, J, K, and M–O) indicate cells labeled with both markers. ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001. Scale bars: 100 μm (D–I); 25 μm (J and K). WT, wild type.