Exercise Promotes Axon Regeneration of Newborn Striatonigral and Corticonigral Projection Neurons in Rats after Ischemic Stroke

Newborn striatal neurons induced by middle cerebral artery occlusion (MCAO) can form functional projections targeting into the substantia nigra, which should be very important for the recovery of motor function. Exercise training post-stroke improves motor recovery in clinic patients and increases striatal neurogenesis in experimental animals. This study aimed to investigate the effects of exercise on axon regeneration of newborn projection neurons in adult rat brains following ischemic stroke. Rats were subjected to a transient MCAO to induce focal cerebral ischemic injury, followed by 30 minutes of exercise training daily from 5 to 28 days after MCAO. Motor function was tested using the rotarod test. We used fluorogold (FG) nigral injection to trace striatonigral and corticonigral projection neurons, and green fluorescent protein (GFP)-targeting retroviral vectors combined with FG double labeling (GFP⁺ -FG⁺) to detect newborn projection neurons. The results showed that exercise improved the recovery of motor function of rats after MCAO. Meanwhile, exercise also increased the levels of BDNF and VEGF, and reduced Nogo-A in ischemic brain. On this condition, we further found that exercise significantly increased the number of GFP⁺ -FG⁺ neurons in the striatum and frontal and parietal cortex ipsilateral to MCAO, suggesting an increase of newborn striatonigral and corticonigral projection neurons by exercise post-stroke. In addition, we found that exercise also increased NeuN⁺ and FG⁺ cells in the striatum and frontal and parietal cortex, the ischemic territory, and tyrosine hydroxylase (TH) immunopositive staining cells in the substantia nigra, a region remote from the ischemic territory. Our results provide the first evidence that exercise can effectively enhance the capacity for regeneration of newborn projection neurons in ischemic injured mammalian brains while improving motor function. Our results provide a very important cellular mechanism to illustrate the effectiveness of rehabilitative treatment post-stroke in the clinic.     

Yangyin Tongnao granules enhance neurogenesis in the peri-infarct area and upregulate brain-derived neurotrophic factor and vascular endothelial growth factor after focal cerebral ischemic infarction in rats

Yangyin Tongnao granules (YYTNG) have been extensively applied in the treatment of brain injury, mainly due to its antioxidant effects, inhibition of apoptosis, and enhancement of blood circulation. To analyze the effect of YYTNG on the recovery of neurological function and neurogenesis in the peri-infarct area after cerebral ischemic infarction in rats and to elucidate its role in the neuroprotective mechanism of stroke, Sprague–Dawley (SD) rats were subjected to middle cerebral artery occlusion (MCAO) for 90 min followed by reperfusion. Rats were randomly divided into five groups: sham, MCAO, and YYTNG-treated rats given doses of 0.83, 1.65, or 3.3 g kg^?1 day^?1. The YYTNG-treated groups (1.65 and 3.3 g kg^?1 day^?1) showed higher neurological scores and a lower infarct volume than the MCAO group on day 3 after MCAO. Furthermore, the YYTNG-treated groups (0.83, 1.65, and 3.3 g kg^?1 day^?1) showed higher neurological scores on day 7 after MCAO. The number of BrdU⁺/nestin⁺, BrdU⁺/NeuN⁺, and BrdU⁺/GFAP⁺ cells in the peri-infarct area 7 days after MCAO was significantly increased in the YYTNG-treated groups in a dose-dependent manner. The protein expression levels of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) were significantly higher in all three YYTNG-treated groups than in the MCAO group. Based on these results, administration of YYTNG post ischemia could ameliorate neurological function deficits in rats with MCAO. The therapeutic effect of YYTNG may be due to the promotion of neurogenesis in the peri-infarct area and the upregulation of neuroprotective factors BDNF and VEGF in MCAO rats.

     

Role of Neuronal NADPH Oxidase 1 in the Peri-Infarct Regions after Stroke

The molecular mechanism underlying the selective vulnerability of neurons to oxidative damage caused by ischemia—reperfusion (I/R) injury remains unknown. We sought to determine the role of NADPH oxidase 1 (Nox1) in cerebral I/R-induced brain injury and survival of newborn cells in the ischemic injured region. Male Wistar rats were subjected to 90 min middle cerebral artery occlusion (MCAO) followed by reperfusion. After reperfusion, infarction size, level of superoxide and 8-hydroxy-2′-deoxyguanosine (8-oxo-2dG), and Nox1 immunoreactivity were determined. RNAi-mediated knockdown of Nox1 was used to investigate the role of Nox1 in I/R-induced oxidative damage, neuronal death, motor function recovery, and ischemic neurogenesis. After I/R, Nox1 expression and 8-oxo-2dG immunoreactivity was increased in cortical neurons of the peri-infarct regions. Both infarction size and neuronal death in I/R injury were significantly reduced by adeno-associated virus (AAV)-mediated transduction of Nox1 short hairpin RNA (shRNA). AAV-mediated Nox1 knockdown enhanced functional recovery after MCAO. The level of survival and differentiation of newborn cells in the peri-infarct regions were increased by Nox1 inhibition. Our data suggest that Nox-1 may be responsible for oxidative damage to DNA, subsequent cortical neuronal degeneration, functional recovery, and regulation of ischemic neurogenesis in the peri-infarct regions after stroke.     

Enhanced neurogenesis and cell migration following focal ischemia and peripheral stimulation in mice

Peripheral stimulation and physical therapy can promote neurovascular plasticity and functional recovery after CNS disorders such as ischemic stroke. Using a rodent model of whisker-barrel cortex stroke, we have previously demonstrated that whisker activity promotes angiogenesis in the penumbra of the ischemic barrel cortex. This study explored the potential of increased peripheral activity to promote neurogenesis and neural progenitor migration toward the ischemic barrel cortex. Three days after focal barrel cortex ischemia in adult mice, whiskers were manually stimulated (15 min x 3 times/day) to enhance afferent signals to the ischemic barrel cortex. 5-Bromo-2'-deoxyuridine (BrdU, i.p.) was administered once daily to label newborn cells. At 14 days after stroke, whisker stimulation significantly increased vascular endothelial growth factor and stromal-derived factor-1 expression in the penumbra. The whisker stimulation animals showed increased doublecortin (DCX) positive and DCX/BrdU-positive cells in the ipsilateral corpus of the white matter but no increase in BrdU-positive cells in the subventricular zone, suggesting a selective effect on neuroblast migration. Neurogenesis indicated by neuronal nuclear protein and BrdU double staining was also enhanced by whisker stimulation in the penumbra at 30 days after stroke. Local cerebral blood flow was better recovered in mice that received whisker stimulation. It is suggested that the enriched microenvironment created by specific peripheral stimulation increases regenerative responses in the postischemic brain and may benefit long-term functional recovery from ischemic stroke.     

Effects of over‐expression of HIF‐1alpha in bone marrow‐derived mesenchymal stem cells on traumatic brain injury

Mesenchymal stem cells (MSCs) have been shown to play therapeutic effect in traumatic brain injury (TBI). To augment the therapeutic effect, MSCs could be engineered to over‐express genes that are beneficial for treatment. In the present study, we over‐expressed hypoxia inducible factor (HIF)‐1alpha in bone marrow derived MSCs (BM‐MSCs) and sought to investigate whether HIF‐1alpha could enhance the therapeutic effect of MSCs in a mouse model of TBI. Balb/c mice were subjected to controlled cortical impact injury and MSCs were transplanted intravenously at 6 h after injury. The lesion volume and brain water content were measured and the neurological function was assessed by modified neurologic severity score tests. Double‐labeled immunofluorescence for BrdU and NeuU was performed to determine angiogenesis and neurogenesis. The expression of erythropoietin (EPO) and vascular endothelial growth factor (VEGF) was measured by quantitative RT‐PCR and western blotting. After TBI, mice received BM‐MSCs over‐expressing HIF‐1alpha showed significantly more functional recovery, reduced brain damage, increased angiogenesis and neurogenesis and increased expression of VEGF and EPO, compared with control mice or mice treated with non‐transduced BM‐MSCs. Over‐expression of HIF‐1alpha enhanced BM‐MSCs induced improvement of neurological recovery after TBI, by stimulating angiogenesis and neurogenesis.     

Motor Enrichment and the Induction of Plasticity Before or After Brain Injury

Voluntary exercise, treadmill activity, skills training, and forced limb use have been utilized in animal studies to promote brain plasticity and functional change. Motor enrichment may prime the brain to respond more adaptively to injury, in part by upregulating trophic factors such as GDNF, FGF-2, or BDNF. Discontinuation of exercise in advance of brain injury may cause levels of trophic factor expression to plummet below baseline, which may leave the brain more vulnerable to degeneration. Underfeeding and motor enrichment induce remarkably similar molecular and cellular changes that could underlie their beneficial effects in the aged or injured brain. Exercise begun before focal ischemic injury increases BDNF and other defenses against cell death and can maintain or expand motor representations defined by cortical microstimulation. Interfering with BDNF synthesis causes the motor representations to recede or disappear. Injury to the brain, even in sedentary rats, causes a small, gradual increase in astrocytic expression of neurotrophic factors in both local and remote brain regions. The neurotrophic factors may inoculate those areas against further damage and enable brain repair and use-dependent synaptogenesis associated with recovery of function or compensatory motor learning. Plasticity mechanisms are particularly active during time-windows early after focal cortical damage or exposure to dopamine neurotoxins. Motor and cognitive impairments may contribute to self-imposed behavioral impoverishment, leading to a reduced plasticity. For slow degenerative models, early forced forelimb use or exercise has been shown to halt cell loss, whereas delayed rehabilitation training is ineffective and disuse is prodegenerative. However, it is possible that, in the chronic stages after brain injury, a regimen of exercise would reactivate mechanisms of plasticity and thus enhance rehabilitation targeting residual functional deficits.     

δ-Opioid Receptor Activation Rescues the Functional TrkB Receptor and Protects the Brain from Ischemia-Reperfusion Injury in the Rat

Objectives

δ-opioid receptor (DOR) activation reduced brain ischemic infarction and attenuated neurological deficits, while DOR inhibition aggravated the ischemic damage. The underlying mechanisms are, however, not well understood yet. In this work, we asked if DOR activation protects the brain against ischemic injury through a brain-derived neurotrophic factor (BDNF) -TrkB pathway.

Methods

We exposed adult male Sprague-Dawley rats to focal cerebral ischemia, which was induced by middle cerebral artery occlusion (MCAO). DOR agonist TAN-67 (60 nmol), antagonist Naltrindole (100 nmol) or artificial cerebral spinal fluid was injected into the lateral cerebroventricle 30 min before MCAO. Besides the detection of ischemic injury, the expression of BDNF, full-length and truncated TrkB, total CREB, p-CREB, p-ATF and CD11b was detected by Western blot and fluorescence immunostaining.

Results

DOR activation with TAN-67 significantly reduced the ischemic volume and largely reversed the decrease in full-length TrkB protein expression in the ischemic cortex and striatum without any appreciable change in cerebral blood flow, while the DOR antagonist Naltrindole aggregated the ischemic injury. However, the level of BDNF remained unchanged in the cortex, striatum and hippocampus at 24 hours after MCAO and did not change in response to DOR activation or inhibition. MCAO decreased both total CREB and pCREB in the striatum, but not in the cortex, while DOR inhibition promoted a further decrease in total and phosphorylated CREB in the striatum and decreased pATF-1 expression in the cortex. In addition, MCAO increased C11b expression in the cortex, striatum and hippocampus, and DOR activation specifically attenuated the ischemic increase in the cortex but not in the striatum and hippocampus.

Conclusions

DOR activation rescues TrkB signaling by reversing ischemia/reperfusion induced decrease in the full-length TrkB receptor and reduces brain injury in ischemia/reperfusion     

Impact of treadmill running and sex on hippocampal neurogenesis in the mouse model of amyotrophic lateral sclerosis

Hippocampal neurogenesis in the subgranular zone (SGZ) of dentate gyrus (DG) occurs throughout life and is regulated by pathological and physiological processes. The role of oxidative stress in hippocampal neurogenesis and its response to exercise or neurodegenerative diseases remains controversial. The present study was designed to investigate the impact of oxidative stress, treadmill exercise and sex on hippocampal neurogenesis in a murine model of heightened oxidative stress (G93A mice). G93A and wild type (WT) mice were randomized to a treadmill running (EX) or a sedentary (SED) group for 1 or 4 wk. Immunohistochemistry was used to detect bromodeoxyuridine (BrdU) labeled proliferating cells, surviving cells, and their phenotype, as well as for determination of oxidative stress (3-NT; 8-OHdG). BDNF and IGF1 mRNA expression was assessed by in situ hybridization. Results showed that: (1) G93A-SED mice had greater hippocampal neurogenesis, BDNF mRNA, and 3-NT, as compared to WT-SED mice. (2) Treadmill running promoted hippocampal neurogenesis and BDNF mRNA content and lowered DNA oxidative damage (8-OHdG) in WT mice. (3) Male G93A mice showed significantly higher cell proliferation but a lower level of survival vs. female G93A mice. We conclude that G93A mice show higher hippocampal neurogenesis, in association with higher BDNF expression, yet running did not further enhance these phenomena in G93A mice, probably due to a 'ceiling effect' of an already heightened basal levels of hippocampal neurogenesis and BDNF expression.     

Neuroprotective effects of VEGF administration after focal cerebral ischemia/reperfusion: dose response and time window

Administration of vascular endothelial growth factor (VEGF) has been shown to increase cerebral blood flow and reduce neurological damage after experimental ischemic brain injury. The purpose of this study was to examine the optimal dose and time window for the neuroprotective effect of VEGF when administrated after focal ischemia/reperfusion injury in rabbits. Focal cerebral ischemia/reperfusion was induced by the middle cerebral artery occlusion (MCAO) method. In a dose response experiment, low (1.25 ng/μL), middle (2.5 ng/μL) and high (5.0 ng/μL) doses of VEGF were administered 2h after MCAO by the route of perifocal region. The VEGF at a dose of middle (2.5 ng/μL) displayed excellent effects on neuroprotective efficacy for focal cerebral ischemia/reperfusion injury. In another experiment, 2.5 ng/μL VEGF was administered at times varying from 2 to 8h after MCAO. Infarct volume, water content and neurological deficits were significantly reduced when VEGF was given at 2 and 3h after injury. The protective effect was less when the same dose was given at the later times. Thus, the present findings indicated that VEGF reduced ischemic neuronal danger with a therapeutic time window within the first 3h of transient MCAO and may be useful in the treatment of acute ischemic stroke in humans.     

Artemisinin attenuated ischemic stroke induced cell apoptosis through activation of ERK1/2/CREB/BCL-2 signaling pathway in vitro and in vivo

Ischemic stroke is characterized by the presence of both brain ischemic and reperfusion-induced injuries in the brain, leading to neuronal dysfunction and death. Artemisinin, an FDA-approved antimalarial drug, has been reported to have neuroprotective properties. However, the effect of artemisinin on ischemic stroke is not known. In the present study, we investigated the effect of artemisinin on ischemic stroke using an oxygen-glucose deprivation/reperfusion (OGD/RP) cellular model and a mouse middle cerebral artery occlusion (MCAO) animal model and examined the underlying mechanisms. The obtained results revealed that a subclinical antimalarial concentration of artemisinin increased cell viability and decreased LDH release and cell apoptosis. Artemisinin also attenuated the production of reactive oxygen species (ROS) and the loss of mitochondrial membrane potential (Δψm). Importantly, artemisinin attenuated the infarction volume and the brain water content in the MCAO animal model. Artemisinin also improved neurological and behavioural outcomes and restored grasp strength and the recovery of motor function in MCAO animals. Furthermore, artemisinin treatment significantly inhibited the molecular indices of apoptosis, oxidative stress and neuroinflammation and activated the ERK1/2/CREB/BCL-2 signaling pathway. Further validation of the involved signaling pathway by the ERK1/2 inhibitor PD98059 revealed that inhibiting the ERK1/2 signaling pathway or silencing ERK1/2 reversed the neuroprotective effects of artemisinin. These results indicate that artemisinin provides neuroprotection against ischemic stroke via the ERK1/2/CREB/BCL-2 signaling pathway. Our study suggests that artemisinin may play an important role in the prevention and treatment of stroke.     

Baoyuan Capsule promotes neurogenesis and neurological functional recovery through improving mitochondrial function and modulating PI3K/Akt signaling pathway

BackgroundBao Yuan Capsule (BYC) is a patented Chinese medicinal formula for health promotion but its application for ischemic stroke remains unknown. In this study, we proposed the hypothesis that BYC could promote neurogenesis and neurological functional recovery through promoting mitochondrial function and activating PI3K/Akt signaling pathway.MethodsWe firstly performed chemical identification studies by using QIT-TOF-MS technology. Then, we investigated the effects of BYC (1 g/kg, 2 g/kg, 4 g/kg per day) on improving the recovery of the neurological functions in transient middle cerebral artery occlusion (MCAO) ischemic mice.ResultsWe tentatively characterized 36 compounds from the BYC extractions. At dosage of 4 g/kg, BYC effectively improved locomotor ability, attenuated anxiety-like behaviors, and enhanced the exploring behaviors, learning and memory capability in the transient MCAO ischemic mice. BYC treatment promoted neural stem cell differentiations in the subventricular zone (SVZ) and subgranular zone (SGZ) of the MCAO mice. BYC also up-regulated the expression of Aconitase 2 (ACO2), Succinate dehydrogenase complex, subunit A (SDHA), phosphorylation of AMP-activated protein kinase (p-AMPK), protein kinase B (p-Akt) and glycogen synthase kinase 3β (p-GSK3β) in the hippocampus of the MCAO mice. BYC (200 µg/ml) significantly improved the mitochondrial functions in cultured mouse multipotent neural stem like C17.2 cells. BYC treatment also promoted neuronal differentiations in the C17.2 cells under oxygen-glucose deprivation (OGD) condition. The neurogenetic effects were abolished by co-treatments of ATP synthesis inhibitor oligomycin and PI3K/Akt inhibitor wortmannin. Moreover, Akt phosphorylation was dramatically reduced by oligomycin.ConclusionBYC could promote neurogenesis and neurological functional recovery in post ischemic brains by regulating the mitochondrial functions and Akt signaling pathway.     

The effects of voluntary, involuntary, and forced exercises on brain-derived neurotrophic factor and motor function recovery: a rat brain ischemia model

Background

Stroke rehabilitation with different exercise paradigms has been investigated, but which one is more effective in facilitating motor recovery and up-regulating brain neurotrophic factor (BDNF) after brain ischemia would be interesting to clinicians and patients. Voluntary exercise, forced exercise, and involuntary muscle movement caused by functional electrical stimulation (FES) have been individually demonstrated effective as stroke rehabilitation intervention. The aim of this study was to investigate the effects of these three common interventions on brain BDNF changes and motor recovery levels using a rat ischemic stroke model.

Methodology/Principal Findings

One hundred and seventeen Sprague-Dawley rats were randomly distributed into four groups: Control (Con), Voluntary exercise of wheel running (V-Ex), Forced exercise of treadmill running (F-Ex), and Involuntary exercise of FES (I-Ex) with implanted electrodes placed in two hind limb muscles on the affected side to mimic gait-like walking pattern during stimulation. Ischemic stroke was induced in all rats with the middle cerebral artery occlusion/reperfusion model and fifty-seven rats had motor deficits after stroke. Twenty-four hours after reperfusion, rats were arranged to their intervention programs. De Ryck''s behavioral test was conducted daily during the 7-day intervention as an evaluation tool of motor recovery. Serum corticosterone concentration and BDNF levels in the hippocampus, striatum, and cortex were measured after the rats were sacrificed. V-Ex had significantly better motor recovery in the behavioral test. V-Ex also had significantly higher hippocampal BDNF concentration than F-Ex and Con. F-Ex had significantly higher serum corticosterone level than other groups.

Conclusion/Significance

Voluntary exercise is the most effective intervention in upregulating the hippocampal BDNF level, and facilitating motor recovery. Rats that exercised voluntarily also showed less corticosterone stress response than other groups. The results also suggested that the forced exercise group was the least preferred intervention with high stress, low brain BDNF levels and less motor recovery.     

Berberine Ameliorates MCAO Induced Cerebral Ischemia/Reperfusion Injury via Activation of the BDNF–TrkB–PI3K/Akt Signaling Pathway

Cerebral ischemic injury remains associated with high mortality rates and lacks effective therapeutic intervention. Berberine (BBR) possesses anti-oxidant, anti-inflammatory, and anti-tumor activities, as well as potent neuroprotective effects. Although recent studies have examined the neuroprotective effects of berberine, little is known regarding its usefulness in treating cerebral ischemia. Thus, the aim of this study is to investigate the possible effect and the mechanism of berberine against cerebral ischemic injury using the middle cerebral artery occlusion (MCAO) model. Rats were randomly divided into three groups: control group, MCAO group, and MCAO?+?BBR group. Modified neurological severity score tests (mNSS) and infarct volumes were measured to determine the neuroprotective effects of berberine. Neuronal survival in striatum was examined by TUNEL staining and immunohistochemistry. Western blotting measured the expression of BDNF, TrkB, p-Akt and cleaved caspase-3. The results demonstrated that BBR could significantly protect against MCAO. Berberine also increased the expression of BDNF, TrkB, and p-Akt, which were reduced after MCAO. Furthermore, treatment with BBR declined the apoptosis-related proteins induced by MCAO. However, treatment with LY294002 (PI3K inhibitor) reversed the BBR-induced increases in BDNF and p-Akt proteins and decreased cleaved caspase-3 protein expression in focal cerebral ischemic rats. In summary, our results demonstrated that BBR could exert neuroprotective effects through reduction of striatum apoptosis via the BDNF–TrkB–PI3K/Akt signaling pathway.     

银杏叶提取物促进脑缺血半暗带神经元自噬提高神经保护作用

银杏叶提取物(ginkgo biloba extract-761,EGb-761)注射液在中国常作为辅助药物被用于治疗脑卒中,但是,其潜在的细胞和药理机制尚未完全了解.该研究旨在探讨EGb-761是否通过调节缺血性脑卒中半暗带神经元的自噬从而发挥保护作用.采用雄性SD大鼠大脑中动脉闭塞(middle cerebral ...     

Quercetin Attenuates Cell Apoptosis in Focal Cerebral Ischemia Rat Brain Via Activation of BDNF–TrkB–PI3K/Akt Signaling Pathway

Many studies have demonstrated that apoptosis play an important role in cerebral ischemic pathogenesis and may represent a target for treatment. Neuroprotective effect of quercetin has been shown in a variety of brain injury models including ischemia/reperfusion. It is not clear whether BDNF?CTrkB?CPI3K/Akt signaling pathway mediates the neuroprotection of quercetin, though there has been some reports on the quercetin increased brain-derived neurotrophic factor (BDNF) level in brain injury models. We therefore first examined the neurological function, infarct volume and cell apoptosis in quercetin treated middle cerebral artery occlusion (MCAO) rats. Then the protein expression of BDNF, cleaved caspase-3 and p-Akt were evaluated in either the absence or presence of PI3K inhibitor (LY294002) or tropomyosin receptor kinase B (TrkB) receptor antagonist (K252a) by immunohistochemistry staining and western blotting. Quercetin significantly improved neurological function, while it decreased the infarct volume and the number of TdT mediated dUTP nick end labeling positive cells in MCAO rats. The protein expression of BDNF, TrkB and p-Akt also increased in the quercetin treated rats. However, treatment with LY294002 or K252a reversed the quercetin-induced increase of BDNF and p-Akt proteins and decrease of cleaved caspase-3 protein in focal cerebral ischemia rats. These results demonstrate that quercetin can decrease cell apoptosis in the focal cerebral ischemia rat brain and the mechanism may be related to the activation of BDNF?CTrkB?CPI3K/Akt signaling pathway.     

Neuroprotective effects of treadmill exercise on BDNF and PI3-K/Akt signaling pathway in the cortex of transgenic mice model of Alzheimer’s disease

(AD). Although physical exercise and AD have received attention in the scientific literature, the mechanism through which treadmill exercise may impact the brain insulin signaling of AD has not been elucidated. This study aimed to evaluate the neuroprotective effects of treadmill exercise on apoptotic factors (Bcl-2/Bax ratio, caspase-3), HSP70, COX-2, BDNF and PI3-K/Akt signaling pathway in the cortex of NSE/hPS2m transgenic mice model of AD. Treadmill exercise ameliorated cognitive function in water maze test and significantly increased the level of Bcl-2/Bax ratio and HSP-70 in Tg-exe group compared to Tg-con group; on the other hand, it significantly decreased the expression of caspase-3 and COX-2 in Tg-exe group compared to Tg-con group. In addition, treadmill exercise significantly increased the expression of BDNF and PI3K/Akt in Tg-exe group compared to Tg-con group. Consequently, treadmill exercise improves cognitive function possibly via activating neurotrophic factor, BDNF and PI3k/Akt signaling pathway, and Aβ-induced neuronal cell death in the cortex of Tg mice was markedly suppressed following treadmill exercise. These results suggest that treadmill exercise may be beneficial in preventing or treating Alzheimer’s disease.     

Human Microglia Transplanted in Rat Focal Ischemia Brain Induce Neuroprotection and Behavioral Improvement

Background and Purpose

Microglia are resident immunocompenent and phagocytic cells of central nervous system (CNS), which produce various cytokines and growth factors in response to injury and thereby regulate disease pathology. The purpose of this study is to investigate the effects of microglial transplantation on focal cerebral ischemia model in rat.

Methods

Transient middle cerebral artery occlusion (MCAO) in rats was induced by the intraluminal filament technique. HMO6 cells, human microglial cell line, were transplanted intravenously at 48 hours after MCAO. Functional tests were performed and the infarct volume was measured at 7 and 14 days after MCAO. Migration and cell survival of transplanted microglial cells and host glial reaction in the brain were studied by immunohistochemistry. Gene expression of neurotrophic factors, cytokines and chemokines in transplanted cells and host rat glial cells was determined by laser capture microdissection (LCM) and quantitative real time-PCR.

Results

HMO6 human microglial cells transplantion group demonstrated significant functional recovery compared with control group. At 7 and 14 days after MCAO, infarct volume was significantly reduced in the HMO group. In the HMO6 group, number of apoptotic cells was time-dependently reduced in the infarct core and penumbra. In addition, number of host rat microglia/macrophages and reactive astrocytes was significantly decreased at 7 and 14 days after MCAO in the penumbra. Gene expression of various neurotrophic factors (GDNF, BDNF, VEGF and BMP7) and anti-inflammatory cytokines (IL4 and IL5) was up-regulated in transplanted HMO6 cells of brain tissue compared with those in culture. The expression of GDNF and VEGF in astrocytes in penumbra was significantly up-regulated in the HMO6 group.

Conclusions

Our results indicate that transplantation of HMO6 human microglial cells reduces ischemic deficits and apoptotic events in stroke animals. The results were mediated by modulation of gliosis and neuroinflammation, and neuroprotection provided by neurotrophic factors of endogenous and transplanted cells-origin.     

Expression of neuronal and signaling proteins in penumbra around a photothrombotic infarction core in rat cerebral cortex

Photodynamic impact on animal cerebral cortex using water-soluble Bengal Rose as a photosensitizer, which does not cross the blood-brain barrier and remains in blood vessels, induces platelet aggregation, vessel occlusion, and brain tissue infarction. This reproduces ischemic stroke. Irreversible cell damage within the infarction core propagates to adjacent tissue and forms a transition zone — the penumbra. Tissue necrosis in the infarction core is too fast (minutes) to be prevented, but much slower penumbral injury (hours) can be limited. We studied the changes in morphology and protein expression profile in penumbra 1 h after local photothrombotic infarction induced by laser irradiation of the cerebral cortex after Bengal Rose administration. Morphological study using standard hematoxylin/eosin staining showed a 3-mm infarct core surrounded by 1.5–2.0 mm penumbra. Morphological changes in the penumbra were lesser and decreased towards its periphery. Antibody microarrays against 224 neuronal and signaling proteins were used for proteomic study. The observed upregulation of penumbra proteins involved in maintaining neurite integrity and guidance (NAV3, MAP1, CRMP2, PMP22); intercellular interactions (N-cadherin); synaptic transmission (glutamate decarboxylase, tryptophan hydroxylase, Munc-18-1, Munc-18-3, and synphilin-1); mitochondria quality control and mitophagy (PINK1 and Parkin); ubiquitin-mediated proteolysis and tissue clearance (UCHL1, PINK1, Parkin, synphilin-1); and signaling proteins (PKBα and ERK5) could be associated with tissue recovery. Downregulation of PKC, PKCβ1/2, and TDP-43 could also reduce tissue injury. These changes in expression of some neuronal proteins were directed mainly to protection and tissue recovery in the penumbra. Some upregulated proteins might serve as markers of protection processes in a penumbra.     

Effects of Mesenchymal Stem Cell Treatment on the Expression of Matrix Metalloproteinases and Angiogenesis during Ischemic Stroke Recovery

Background

The efficacy of mesenchymal stem cell (MSC) transplantation in ischemic stroke might depend on the timing of administration. We investigated the optimal time point of MSC transplantation. After MSC treatment, we also investigated the expression of matrix metalloproteinases (MMPs), which play a role in vascular and tissue remodeling.

Methods

Human bone marrow-derived MSCs (2 × 10⁶, passage 5) were administrated intravenously after permanent middle cerebral artery occlusion (MCAO) was induced in male Sprague-Dawley rats. First, we determined the time point of MSC transplantation that led to maximal neurological recovery at 1 h, 1 day, and 3 days after MCAO. Next, we measured activity of MMP-2 and MMP-9, neurological recovery, infarction volume, and vascular density after transplanting MSCs at the time that led to maximal neurological recovery.

Results

Among the MSC-transplanted rats, those of the MSC 1-hour group showed maximal recovery in the rotarod test (P = 0.023) and the Longa score (P = 0.018). MMP-2 activity at 1 day after MCAO in the MSC 1-hour group was significantly higher than that in the control group (P = 0.002), but MMP-9 activity was not distinct. The MSC 1-hour group also showed smaller infarction volume and higher vascular density than did the control group.

Conclusions

In a permanent model of rodent MCAO, very early transplantation of human MSCs (1 h after MCAO) produced greater neurological recovery and decreased infraction volume. The elevation of MMP-2 activity and the increase in vascular density after MSC treatment suggest that MSCs might help promote angiogenesis and lead to neurological improvement during the recovery phase after ischemic stroke.     

Delayed neuroprotection against cerebral ischemia reperfusion injury: putative role of BDNF and GSK-3β

Aim: Numerous studies have demonstrated the possible neuroprotective role of lithium treatment against neurological disorders. However, the role of lithium in delayed phase of neuronal death against focal ischemia has not been explored. Therefore, the present study was designed to investigate the effect and molecular mechanisms of post-lithium treatment against cerebral ischemic reperfusion (I/R) injury and associated cognitive deficits in rats. Methods: I/R injury was induced by right middle cerebral artery occlusion and lithium (40 and 60?mg/kg) were given intraperitoneally, 24?h after the insult and continued for 1 week with 24-h interval. Using Lasser Doppler, cerebral blood flow was monitored before, during and after MCAO induction. Besides behavioral, biochemical, and histological evaluation, levels of tumor necrosis factor alpha (TNF-α) and brain-derived neurotrophic factor (BDNF) were also estimated. Results: I/R injury resulted in significant elevation of neurological deficits, oxidative stress, neuroinflammation, and cognitive impairments. We found that lithium injection, 24?h after I/R-injury continued for 1 week, dose dependently prevented behavioral abnormality and cognitive impairments. Moreover, lithium attenuated the levels of oxidative stress and pro-inflammatory-cytokines TNF-α level. Further, lithium treatments significantly reduced neuronal damage and augmented healthy neuronal count and improved neuronal density in hippocampus. These neuroprotective effects of delayed lithium treatment were associated with upregulation of neurotrophic factor BDNF levels. Conclusion: Delayed lithium treatment provides neuroprotection against cerebral I/R injury and associated cognitive deficits by upregulating BDNF expression that opens a new avenue to treat I/R injury even after active cell death.