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. 2006 May 31;26(22):5978–5989. doi: 10.1523/JNEUROSCI.0302-06.2006

Figure 1.

Figure 1.

Anatomical and biochemical characterization of CNTF-activated astrocytes. A–C, GFAP (A), vimentin (B), and nestin (C) immunohistochemical staining of rat brain sections after intrastriatal injection of lentiviruses encoding either CNTF or LacZ. CNTF increases the level of expression of GFAP (A) and induces the expression of both vimentin (B) and nestin (C) compared with the control striatum, injected with lenti-LacZ. D, Enlargement of boxes in B shows that CNTF-activated vimentin-positive astrocytes are hypertrophic and have numerous large processes compared with labeled astrocytes in the lenti-LacZ striatum that are only visible along the needle track (arrow). E, Immunoblot analysis confirms that the level of expression of GFAP is significantly increased in the lenti-CNTF striatum as compared with striata of rats injected with lenti-LacZ or vehicle (Veh). Vimentin and nestin are only detected in the lenti-CNTF group. CNTF-activated astrocytes also significantly overexpress connexin 43 (Cx-43). F, The level of expression of the cyclin PCNA is low and unchanged between groups. By comparison, the embryonic E15 brain (positive control) shows a high level of expression of PCNA resulting from active proliferation. G, Left, Confocal analysis of immunofluorescent double labeling of nestin (red) and GFAP (green) in the lenti-CNTF striatum shows that both filaments are coexpressed in the same cell. G, Right, Vimentin (red) and GFAP (green) are also colocalized in the same astrocytes. These results suggest that CNTF alters the phenotype of the vast majority of striatal astrocytes without inducing major proliferation or formation of new astroglial cells. H, The phosphorylated form of STAT3 is only detected in the lenti-CNTF group, whereas total STAT3 levels are similar in all groups. I, In control conditions, STAT3 has a neuropil-like localization. In the lenti-CNTF group, several cells expressing S100β present an intense perinuclear staining with STAT3 (arrowhead), which may reflect STAT3 translocation toward the nucleus in astrocytes. J, The cells showing a perinuclear location of STAT3 coexpress vimentin but not NeuN, suggesting that CNTF signaling pathways are specifically activated in astrocytes. Images are representative of four to five animals per group at 2 weeks and 2–6 months after infection. Scale bars: (in C) A–C, 1 mm; D, 50 μm; G, I, J, 20 μm.