Fig. 9

Elevated NRG1 expression in the SVZ and cortex of injured mice, localized in microglial cells and detected in the CSF. A Scheme of experimental procedures. Mechanical cortical lesions were unilaterally performed in the adult mouse primary motor cortex (CTX). Mice were sacrificed 7- or 14-days post injury (dpi). Only the group “14 dpi + EOF2” was intranasally treated with EOF2 5 µM from the day of the injury until sacrifice. B Mouse cerebrospinal fluid (CSF) were obtained from non-injure mice (sham) and from injured mice at day 7 and day 14 post-injury (dpi). The graph shows neuregulin 1 (NRG1) detection (ng/mL) in CSF. *p = 0.04 Sham vs. 7dpi; p = 0.042 Sham vs. 14dpi + EOF2 in one-way ANOVA. 6 animals were used per group. C Relative mRNA expression of NRG1, and ErbB4 in the injured cortex (ipsilateral, ipsi) and in non-injured cortex (contralateral, contra) at 7 dpi and at 14 dpi. mRNA expression was measured using real time qPCR. *p = 0.042 7dpi CTX NRG1 (contra vs. ipsi). 6 animals were used per group D Relative mRNA expression of NRG1 and ErbB4 in the subventricular zone (SVZ) of the injured ipsilateral side and non-injured side 7 dpi and a 14 dpi. mRNA expression was measured using real time qPCR. The data show the means ± SEM of 6 animals per group. *p = 0.0472 7dpi SVZ NRG1 contra vs. ipsi; *p = 0.0313 14dpi SVZ ErbB4 contra vs. ipsi. E–H Representative confocal images showing the CTX (E, F) and SVZ (G, H) of 7 dpi mice. Images were processed for the immunodetection of NRG1. The dotted line indicates the limit of the lesion (L) or lateral ventricle (LV), and the scale bar represents 25 μm. I-L Representative confocal images showing the colocalization of NRG1 with GFAP (I), Iba1 (J,L) and Nestin (K) in the Cortex CTX (I-K) and SVZ (L) of 7 dpi mice. Scale bars represent 25 µm. M Graph represents the number of NRG1 cells in the contralateral cortex compared to the perilesional area of 7 dpi mice. The data show means ± SEM of 6 animals per group. Statistical analysis: *p < 0.0001 compared the ipsilateral site with the contralateral side in a Student’s t test for equal-variance unpaired samples. N Graph shows NRG1 burden as a percentage of the total SVZ area in contralateral and ipsilateral SVZ of 7 dpi mice. Data show Means ± SEM of 6 animals per group. Statistical analysis: *p < 0.0001 compared the ipsilateral site with the contralateral side in a Student’s t test for equal-variance unpaired samples. O Quantification of the colocalization of NRG1 with GFAP, Iba1 or Nestin in the injured cortex of 7 dpi mice. The data show the means ± SEM of 6 animals per group; *p < 0.0001 ipsi NRG1⁺GFAP⁺ vs NRG1⁺Iba1⁺; *p = 0.0431 NRG1⁺GFAP⁺ vs NRG1⁺Nestin⁺; *p < 0.0001 NRG1⁺Iba1⁺ vs NRG1⁺Nestin⁺ in one-way ANOVA, followed by posthoc Tukey test. P Quantification of the colocalization of NRG1 with Iba1 in the ipsilateral SVZ of 7 dpi mice. Data are the mean ± SEM; n = 6 animals per group. Q Percentage of the number of Iba1⁺ cells per mm³ that also express NRG1 (Iba1⁺NRG1⁺ cells per mm³) in contralateral and ipsilateral SVZ of 7 dpi mice. n = 6 animals per group