Restraint stress activated hypothalamic neurons in TgCRND8 mice.

<p>A–D: Cross sections of the brains stained with c-fos immunohistochemical staining in PVN (A and C) and SON (B and D) of TgCRND8 mice at the age of 4 months undergone restraint stress (A and B) and non-stress treatment (C and D). E: Quantitative analysis of number of c-fos immunoreactive nuclei in SON of stressed and non-stressed TgCRND8 mice. * indicates statistical differences when compared with their age-matched non-stressed controls at <i>p</i><0.01. Scale bar = 150 µm.</p

Behavioral Stress Fails to Accelerate the Onset and Progression of Plaque Pathology in the Brain of a Mouse Model of Alzheimer's Disease

<div><p>Conflicting findings exist regarding the link between environmental factors and development of Alzheimer's disease (AD) in a variety of transgenic mouse models of AD. In the present study, we investigated the effect of behavioral stress on the onset and progression of Aβ pathology in the brains of TgCRND8 mice, a transgenic mouse model of AD. One group of TgCRND8 mice was subjected to restraint stress starting at 1 month of age until they were 3 months old, while restraint stress in the second group started at 4 months of age until they were 6 months old. After 2 months of treatment, no differences in the soluble, formic acid extracted, or histologically detected Aβ deposition in the cortical and hippocampal levels were found between non-stressed and stressed mice. These results showed that restraint stress alone failed to aggravate amyloid pathology when initiated either before or after the age of amyloid plaque deposition in TgCRND8 mice, suggesting that if stress aggravated AD phenotype, it may not be via an amyloid-related mechanism in the TgCRND8 mice. These findings are indicative that plaque load per se may not be used as a significant criterion for evaluating the effect of stress on AD patients.</p></div

Effects of restraint stress on Aβ1-40 or Aβ1-42 levels in TgCRND8 mice.

<p>ELISA was used to measure Aβ levels in hippocampal tissues after completion of the restraint stress procedure. The data were expressed as means ± SEM. Restraint stress had no significant effect on Aβ levels in either soluble fraction or nonsoluble fraction.</p

Regeneration estimated by GAP-43 expression in the post surgery spinal cord.

<p>In transverse sections at C6, GAP-43 immunoreactivity (ir) is concentrated in the ventral horn (VH) on the lesion side on days 7, 14 and 21 post surgery, reaching maximal level on day 14, in both the control (A–C) and the mutant (D–F). At each time-point, GAP-43 expression is higher in the control than the mutant (G). *, <i>P</i><0.05; **, <i>P</i><0.01; comparison at different time-points with <i>t</i>-test, n = 4 mice in each group.</p

Three-Dimensional Nanofiber Hybrid Scaffold Directs and Enhances Axonal Regeneration after Spinal Cord Injury

Spinal cord injuries (SCIs) are followed by a complex series of events that contribute to the failure of regeneration. To date, there is no robust treatment that can restore the injury-induced loss of function. Since damaged spinal axons do not spontaneously regenerate in their native inhibitory microenvironment, a combined application of biomaterials and neurotrophic factors that induce nerve regeneration emerges as an attractive treatment for SCIs. In this study, we report the novel use of a three-dimensional (3D) hybrid scaffold to provide contact guidance for regrowth of axons <i>in vivo</i>. The scaffold comprises 3D aligned sparsely distributed poly­(ε-caprolactone-<i>co</i>-ethyl ethylene phosphate) nanofibers that are supported and dispersed within a collagen hydrogel. Neurotrophin-3 was incorporated into the scaffold as an additional biochemical signal. To evaluate the efficacy of the scaffold in supporting nerve regeneration after SCIs, the construct was implanted into an incision injury, which was created at level C5 in the rat spinal cord. After 3 months of implantation, scaffolds with NT-3 incorporation showed the highest average neurite length (391.9 ± 12.9 μm, <i>p</i> ≤ 0.001) as compared to all the other experimental groups. In addition, these regenerated axons formed along the direction of the aligned nanofibers, regardless of their orientation. Moreover, the presence of the hybrid scaffolds did not affect tissue scarring and inflammatory reaction. Taken together, these findings demonstrate that our scaffold design can serve as a potential platform to support axonal regeneration following SCIs

Cross sections of the brains were stained with Thioflavin S staining in TgCRND8 mice at the age of 1 (A), 3 (B) and 6 (C) months.

<p>Scale bar = 100 µm.</p

Restraint stress did not influence cortical and hippocampal amyloid plaque loads.

<p>A–D, Cross sections of the brains stained with bam-10 immunohistochemical staining in TgCRND8 mice at the age of 3 (A, B) or 6 months (C, D) under stress (A, C) and non-stress (B, D). E–F, Quantitative analysis of Aβ deposit burden in either cortex or hippocampus in TgCRND8 mice at the age of 3 (E) or 6 months (F) under stress or non-stress. Scale bar = 300 µm.</p

Macrophages are activated followed root avulsion/re-implantation.

<p>In transverse sections at C5–C7, anti-CD11b immunoreactivity is widely distributed in the white and gray matter on the lesion side with a decreasing trend from day 7 to day 21, in both the control (A–C) and the mutant (D–F). At each time-point, CD11b expression is higher in the control than the mutant (G). VH, ventral horn. *, <i>P</i><0.05; **, <i>P</i><0.01; comparison at different time-points with <i>t</i>-test, n = 4 mice in each group.</p

Expression profile of neurotrophic factors and receptors 7 days post surgery.

<p>Seven days post surgery, injured (R) and intact (L) sides of C5–C7 segments were collected separately for Western blot with anti- TrkB, p75, BDNF, NT-3 and GDNF antibodies in control (Ctrl) and <i>Celsr3|Emx1</i> (Mut) mice, and <i>β</i>-tubulin was used as a control protein (A). The expression level of each protein was normalized to<i>β</i>-tubulin (B). Comparisons were summarized in C. In control mices, the expression of TrkB and BDNF was significantly decreased, but that of p75 was significantly increased, on injured sides (R) compared to intact sides (L). There was not significant difference in expression of neurotrophic factors and receptors between injured and intact sides in mutant mice. On both sides, the expression level of p75 was significantly lower in the mutant than in the control. On injured sides, the expression of TrkB and BDNF was significantly higher in the mutant than in the control although their expression was comparable on intact sides between two groups. “↓”, lower or decreased expression; “↑”, higher or increased expression; “_”, no significant difference; *, <i>P</i><0.05; **, <i>P</i><0.01; Ctrl-L, left side of control mice; Ctrl-R, right side of control mice; Mut-L, left side of mutant mice; Mut-R, right side of mutant mice. Six animals were used in each group and <i>t</i>-test was used for comparisons.</p

After surgery, newly innervated NMJs are less abundant, and muscles more atrophic in <i>Celsr3|Emx1</i> than control mice.

<p>A, B: Five months post surgery, left (L, intact side) and right (R, surgery side) biceps brachii were weighted. The R/L wet weight ratio was 97% in control mice versus 80% in mutant mice (**: <i>P</i><0.01, <i>t</i>-test, n = 10 in each group). C–J: Different classes of NMJ in the biceps at 5 months post surgery, stained with anti-NF200 to label regenerating axon (green), and anti-<i>α</i>-BT to label AchR clusters (red). In remodeled NMJs, thin axon terminals innervate some but not all fragmented AchR clusters (arrows in E, I). Neoformed NMJs are characterized by small AchR clusters innervated by thin axons that lack terminal arbors (asterisks in F, J). Quantification in K, 100 NMJs in each group, n = 4 mice; **: <i>P</i><0.01, one-way ANOVA.</p