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. 2004 Mar 3;24(9):2143–2155. doi: 10.1523/JNEUROSCI.3547-03.2004

Figure 5.

Figure 5.

Increased leukocyte infiltration after ablation of reactive astrocytes adjacent to stab SCI. A-F, L, Transverse sections of upper lumbar spinal cord 14 d after longitudinal stab SCI (arrowheads) in a nontransgenic mouse not given GCV (A, B, E; NT no GCV) or in a GFAP-TK transgenic mouse given GCV (C, D, F, L; Tg+GCV). A-F, Immunohistochemical staining for the leukocyte marker CD45 viewed by bright-field microscopy. B, D, Details, respectively, of boxed areas in A and C. E, F, Details, respectively, of B and D showing CD45-positive cells with the typical appearance of microglia (E) and activated macrophages (F). In the control mouse, there is moderate microglial activation (arrow) but few intensely stained CD45-positive cells with round cell bodies typical of leukocytes in the neural parenchyma adjacent to the injury (A, B, E). In the GFAP-TK transgenic mouse given GCV, the region of astrocyte ablation is densely packed with many intensely stained CD45-positive cells with rounded cell bodies typical of leukocytes, in particular, activated macrophages (C, D, F). G, Mean cell number ± SEM of CD45-immunoreactive cells within the wound margin adjacent to the stab injury (see Fig. 1D); GFAP-TK mice given GCV exhibit a sevenfold greater number compared with control mice; n = 5 per group. ***Significantly different from control, p < 0.001 (ANOVA). H-K, Transverse sections of upper lumbar ventral horn 14 d after injection of vehicle (H) or NMDA (I-K). Cresyl violet staining (H, I) reveals pronounced loss of ventral horn neurons induced by NMDA (I). Immunohistochemical staining for CD45 in an adjacent tissue section reveals modest inflammatory response in ventral horn after NMDA (J). K, L, Laser-scanning confocal microscopy of triple staining for astrocytes (GFAP), inflammatory cells (CD45), and neurons (NeuN) to compare the inflammatory response after injection of NMDA (K) or ablation of astrocytes in GFAP-TK transgenic mice treated with GCV (L). Both experimental conditions cause severe loss of NeuN-positive neurons (K, L). CD45-positive inflammatory cells exhibit a mild inflammatory response after NMDA, which induces pronounced GFAP-positive astrogliosis (K). In contrast, CD45-positive inflammatory cells exhibit a pronounced inflammatory response in the absence of reactive astrocytes (L). Scale bars: A, C, 100 μm; B, D, 50 μm; E, F, 5 μm; H-J, 50 μm; K, L, 15 μm.