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. 2013 Aug 9;14(10):931–937. doi: 10.1038/embor.2013.117

Figure 3.

Figure 3

Sustained STAT3 expression induces de novo formation of midline crossing circuits following pyramidotomy. (A) Schematic representation of the analysis of CST remodelling after unilateral pyramidotomy and injection of Control rAAV or rAAV-STAT3. (B–D) Confocal images of midline crossing fibres in mice injected with Control rAAV (B) or rAAV-STAT3 (C,D) and perfused 3 w (B,C) or 12 w (D) following pyramidotomy. Arrows indicate midline crossing fibres, arrowheads indicate examples of fibres that have already crossed the midline. (E,F) Quantification of the number of fibres exiting ipsilateral to the pyramidotomy from the main CST (E) and crossing the spinal midline (F) in mice injected with Control rAAV (grey bars) or rAAV-STAT3 (red bars) and perfused 1, 3 or 12 w (n=7–10 mice per group) following pyramidotomy. (G) Quantification of the percentage of midline crossing fibres that project to the contralateral (denervated) laminae VI to IX in mice injected with Control rAAV (grey bars) or rAAV-STAT3 (red bars) and perfused 3 or 12 w following pyramidotomy (n=7–10 mice per group). (H) Quantification of the density of midline crossing fibres in the contralateral (denervated) side of the spinal cord at different distances from the midline in mice injected with Control rAAV (grey line) or rAAV-STAT3 (red line) and perfused 12 w following pyramidotomy (n=7–8 mice per group). (I,K) Confocal images (single planes) of contacts between midline crossing forelimb CST collaterals (red) and a short propriospinal neuron (I, green) or a motoneuron (K, green) in mice injected with rAAV-STAT3 and perfused 12 w following the pyramidotomy. (J,L) Quantification of the percentage of short propriospinal neurons (J) and motoneurons (L) contacted by midline crossing forelimb CST collaterals in mice injected with Control rAAV (grey bars) or rAAV-STAT3 (red bars) and perfused 12 w following injury (n=7–8 mice per group). All bars and error bars in this figure represent mean±s.e.m. Statistical analysis was performed using a two-way ANOVA followed by Bonferroni test for E–G, and a one-way repeated ANOVA followed by Tukey test in H and t-tests for J, L. *P<0.05; **P<0.01; ***P<0.001. Scale bars equal 200 μm in D (also for B,C) and 25 μm in I and 10 μm in K. ANOVA, analysis of variance; CST, corticospinal tract; rAAV, recombinant adeno-associated viruses; SC, spinal cord; STAT3, signal transducer and activator of transcription 3.

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