Number of BrdU-positive cells in the DG in different experimental groups (see table under the abscissa;+done, - not done).

<p>(A) Overview and (B) magnified detail (red square) of a 40 µm thick coronal section through the DG 42 days after the first BrdU-injection. BrdU-positive cells are labelled dark brown. (C) The NC group (n = 7) and the CXray group (n = 7) were not significantly different, and the AIA group (n = 7) did not differ from the IC group (n = 10). Both the AIA and the IC group had significantly increased numbers of BrdU-positive cells compared to the NC and CXray groups. The column on the right shows another group of 3 rats which were only immunized but not tested for pain-related or locomotor behavior (IC-wt). This group did not significantly differ from the IC group. Data are presented as means ± SEM. **p<0.01; ***p<0.001.</p

Radiovideographic analysis of locomotion in arthritic and immunized control animals.

<p>(A) Walking sequence (top to bottom) of a representative animal of the AIA-group on day 1 after induction of AIA. Arrows show the inflamed knee joint in relieving posture (hardly any change in the joint angle during walking). (B) Range of motion in the inflamed (left side) and non-inflamed (right side) knee joint during the time course of 14 days in a representative animal of the AIA-group (filled symbols) and one animal of the immunized control group (IC, open symbols). BL - baseline.</p

Percentage of BrdU/NeuN-double-positive cells in the DG in different experimental groups (display as in Figure 4).

<p>Thirty BrdU-positive cells of each animal were analyzed for coexpression of NeuN. (A) Confocal images of an immunofluorescent-labelled section of the DG. NeuN-labelled cells are green and BrdU-positive cells are red. In the merged picture (lowest one) arrows show BrdU-NeuN-double-positive cells. (B) There were no significant differences between the NC and the CXray group (p<i> = </i>1.000) and between the AIA and IC group (p<i> = </i>0.476). AIA group showed a significantly increased percentage of mature neurons compared to NC and CXray group. Data are presented as means ± SEM. *p<0.05; **p<0.01.</p

Lack of correlation between swelling or nociceptive behavior and the total number of BrdU-positive cells in the DG in immunized controls (IC) and AIA rats.

<p>Each circle and dot shows the maximal swelling or pain behavior of an individual rat during the observation period of 42 days. Circles: animals just immunized (IC group), Dots: animals with AIA. (A) Maximum joint swelling versus total BrdU-positive cells. (B) Maximum primary hyperalgesia (minimum mechanical threshold) at the inflamed knee joint versus total BrdU-positive cells. (C) Maximum asymmetry (least force on the inflamed hindlimb) between left and right hindlimb versus total BrdU-positive cells.</p

Swelling and pain-related behavior in the AIA and IC groups.

<p>(A) Joint swelling displayed as delta (Δ) between ipsilateral (inflamed) and contralateral (noninflamed) knee joints during the observation period of 42 days. (B) Primary mechanical hyperalgesia assessed by measuring the withdrawal threshold to pressure applied to the knee. (C) Weight bearing of the rats shown as the relative body weight resting on the inflamed hindlimb. Data are presented as means ± SEM. *p<0.05; **p<0.01; ***p<0.001. BL - baseline.</p

Experimental protocol of the study.

<p>BrdU - bromodeoxyuridine.</p

Adult hippocampal neurogenesis poststroke: More new granule cells but aberrant morphology and impaired spatial memory

<div><p>Stroke significantly stimulates neurogenesis in the adult dentate gyrus, though the functional role of this postlesional response is mostly unclear. Recent findings suggest that newborn neurons generated in the context of stroke may fail to correctly integrate into pre-existing networks. We hypothesized that increased neurogenesis in the dentate gyrus following stroke is associated with aberrant neurogenesis and impairment of hippocampus-dependent memory. To address these questions we used the middle cerebral artery occlusion model (MCAO) in mice. Animals were housed either under standard conditions or with free access to running wheels. Newborn granule cells were labelled with the thymidine analoque EdU and retroviral vectors. To assess memory performance, we employed a modified version of the Morris water maze (MWM) allowing differentiation between hippocampus dependent and independent learning strategies. Newborn neurons were morphologically analyzed using confocal microscopy and Neurolucida system at 7 weeks. We found that neurogenesis was significantly increased following MCAO. Animals with MCAO needed more time to localize the platform and employed less hippocampus-dependent search strategies in MWM versus controls. Confocal studies revealed an aberrant cell morphology with basal dendrites and an ectopic location (e.g. hilus) of new granule cells born in the ischemic brain. Running increased the number of new neurons but also enhanced aberrant neurogenesis. Running, did not improve the general performance in the MWM but slightly promoted the application of precise spatial search strategies. In conclusion, ischemic insults cause hippocampal-dependent memory deficits which are associated with aberrant neurogenesis in the dentate gyrus indicating ischemia-induced maladaptive plasticity in the hippocampus.</p></div

Stroke stimulates neurogenesis in adult dentate gyrus.

<p><b>A,</b> Representative confocal image of dentate gyrus with newly generated neurons (red). B, Higher magnification of new neurons show colabeling of proliferation marker EdU (red) and mature neuronal marker NeuN (blue). <b>C,</b> Quantification of new neurons in animals housed under standard conditions or with free access to running wheels. Bars represent mean ± SEM. Asterisks indicate significant differences (p < 0.05). Scale bars represent 100 μm (A1), 10μm (B1).</p

Stroke animals employ less hippocampus-dependent search strategies.

<p><b>A</b>, Schematic illustration of distinct hippocampus-dependent and -independent search strategies in MWM. <b>B/C,</b> Contribution of single search strategies to group performance in MCAO- and sham operated animals either following standard housing (B) or free access to running wheels (C). Color code as indicated in A.</p

Stroke induces aberrant neurogenesis.

<p><b>A,</b> Morphology of regular (“non-aberrant”) GFP-positive neurons after retroviral tracing in sham operated control. <b>B1-4,</b> Distinct examples of aberrant neurons following stroke expressing additional basal dendrites toward the hilus (bipolar cells). <b>C1,</b> Regular granule cell with characteristic dendritic tree spanning the granule cell layer. Right panel: higher magnification of one dendrite with spines. <b>C2</b>, Aberrant granule cell extending dendrites towards hilus. Right panel: higher magnification of one dendrite with spines. <b>D1-D2</b>, Quantification of spines in aberrant and regular granule cells (D1, total number of spines. D2, percentage of mushroom spines). Scale bars: 10μm (C1, C2 left) and 5μm (C1, C2 right).</p