Adult Rat Subventricular Zone Research Articles

RXR agonist bexarotene modulates the cell‐fate and migration abilities of adult neural stem cells in vitro

AbstractBackgroundTargeting the nuclear RXR receptors has been associated with brain‐specific roles with striking therapeutic potential for Alzheimer’s Disease (AD), with similar observations to its dimerization partners such as LXR and PPAR whose responses are also under influence of RXR activation. Treatment with bexarotene, a selective RXR agonist, leads to significant recovery of cognitive loss in variable mice AD‐like models ‐ and also activates neurodevelopment and plasticity pathways in adult mice brains. Our hypothesis is that neural stem cells (NSC) residing in the adult brain directly respond to bexarotene, leading to improved neurogenesis and other effects compatible with brain recovery.MethodWe employed an in vitro strategy using NSCs isolated from the subventricular zone of adult rats’ brains. Adult NCSs were treated with bexarotene from neurosphere proliferative stage to differentiated states, and the cell‐fate consequences were evaluated through morphometric analysis and immunofluorescence of cell markers.ResultIn proliferative stages, bexarotene‐treated adult NSCs exhibited increased cell outgrowth from neurospheres. Bexarotene treatment also led to changes in the cell fate of differentiating cells, with a marked increase in GFAP staining after differentiation. Relatively to newborn neurons, we found a decrease in DCX positive staining of neuroblasts after bexarotene treatment. However, Tuj1 staining of neurons was preserved. Neurite number, length, and bifurcations in differentiated neurons were unaffected by bexarotene.ConclusionAdult NSCs respond to bexarotene by increasing migration abilities and generating more GFAP+ cells. Results indicate that RXR activation by bexarotene in adult NSCs preserves, but does not activate, neuronal differentiation and neurite complexity. The significance of the increased GFAP+ glial cell population, as well as the decreased DCX+ young neurons, remains to be unrevealed. Finally, we did not observe clear bexarotene‐induced changes in neurosphere proliferation, but the effect of RXR activation over pluripotency in these cells needs further investigation. These findings address a gap in our knowledge regarding the brain effects of bexarotene, substantiating the search and possible application of RXR‐based approaches to AD.

In vitro characterization of subventricular zone isolated neural stem cells, from adult monkey and rat brain.

Neural stem cells (NSCs) are multipotent, self-renewable cells who are capable of differentiating into neurons, astrocytes, and oligodendrocytes. NSCs reside at the subventricular zone (SVZ) of the adult brain permanently to guarantee a lifelong neurogenesis during neural network plasticity or undesirable injuries. Although the specious inaccessibility of adult NSCs niche hampers their in vivo identification, researchers have been seeking ways to optimize adult NSCs isolation, expansion, and differentiation, in vitro. NSCs were isolated from rhesus monkey SVZ, expanded in vitro and then characterized for NSCs-specific markers expression by immunostaining, real-time PCR, flow cytometry, and cell differentiation assessments. Moreover, cell survival as well as self-renewal capacity were evaluated by TUNEL, Live/Dead and colony assays, respectively. In the next step, to validate SVZ-NSCs identity in other species, a similar protocol was applied to isolate NSCs from adult rat's SVZ as well. Our findings revealed that isolated SVZ-NSCs from both monkey and rat preserve proliferation capacity in at least nine passages as confirmed by Ki67 expression. Additionally, both SVZ-NSCs sources are capable of self-renewal in addition to NESTIN, SOX2, and GFAP expression. The mortality was measured meager with over 95% viability according to TUNEL and Live/Dead assay results. Eventually, the multipotency of SVZ-NSCs appraised authentic after their differentiation into neurons, astrocytes, and oligodendrocytes. In this study, we proposed a reliable method for SVZ-NSCs in vitro maintenance and identification, which, we believe is a promising cell source for therapeutic approach to recover neurological disorders and injuries condition.

Correction to Curcumin-Loaded Nanoparticles Potently Induce Adult Neurogenesis and Reverse Cognitive Deficits in Alzheimer's Disease Model via Canonical Wnt/β-Catenin Pathway.

Neurogenesis, a process of generation of new neurons, is reported to be reduced in several neurodegenerative disorders including Alzheimer’s disease (AD). Induction of neurogenesis by targeting endogenous neural stem cells (NSC) could be a promising therapeutic approach to such diseases by influencing the brain self-regenerative capacity. Curcumin, a neuroprotective agent, has poor brain bioavailability. Herein, we report that curcumin-encapsulated PLGA nanoparticles (Cur-PLGA-NPs) potently induce NSC proliferation and neuronal differentiation in vitro and in the hippocampus and subventricular zone of adult rats, as compared to uncoated bulk curcumin. Cur-PLGA-NPs induce neurogenesis by internalization into the hippocampal NSC. Cur-PLGA-NPs significantly increase expression of genes involved in cell proliferation (reelin, nestin, and Pax6) and neuronal differentiation (neurogenin, neuroD1, neuregulin, neuroligin, and Stat3). Curcumin nanoparticles increase neuronal differentiation by activating the Wnt/β-...

Depletion of Hypocretin/Orexin Neurons Increases Cell Proliferation in the Adult Subventricular Zone.

Adult neurogenesis, a specific form of brain plasticity in mammals that occurs in the subventricular zone, is subject to complex regulation. Hypocretin/orexin neurons are implicated in the regulation of sleep and arousal states, among other functions. Here we report for the first time the presence of orexinergic projections within the adult rat subventricular zone. Post-mortem retrograde tracing combined with immunofluorescence indicated orexinergic projections toward the subventricular zone. To establish the relationship between the depletion of orexin neurons and the number of proliferating cells in the subventricular zone, we labeled mitotic cells. Histological analysis revealed proliferating cells to be in close contact with orexinergic fibers. Neurotoxinlesioning of orexin neurons in the lateral hypothalamus significantly activated precursor cell proliferation in the subventricular zone. Furthermore, cell proliferation in both normal and lesioned animals failed to reveal newly born orexin neurons in the lateral hypothalamus. Based on these findings, we suggest that the adult subventricular zone is affected by orexinergic signaling, the functional implication of which must be further elucidated.

The Subventricular Zone Response to Stroke Is Not a Therapeutic Target of Anti-Nogo-A Immunotherapy.

Ischemic stroke is a leading cause of adult disability with no pharmacological treatments to promote the recovery of lost function. Neutralizing antibodies against the neurite outgrowth inhibitor Nogo-A have emerged as a promising treatment for subacute and chronic stroke in animal models; however, whether anti-Nogo-A treatment affects poststroke neurogenesis remains poorly understood. In this study, we confirmed expression of Nogo-A by neuroblasts in the adult rat subventricular zone (SVZ), a major neurogenic niche; however, we found no evidence that Nogo-A was expressed at the surface of these cells. In vitro migration assays demonstrated that Nogo-A signaling induced a modest reduction in neuroblast migration speed, while anti-Nogo-A antibodies had no effect on motility properties. Using a permanent distal middle cerebral artery occlusion model of cortical stroke, we found that the number of proliferating cells in the SVZ was unaffected in response to stroke, while neuroblast mobilization from the SVZ toward the stroke lesion correlated positively with lesion size. However, we found no evidence that proliferation or neuroblast mobilization were affected by anti-Nogo-A antibody treatment. Our results suggest that the SVZ is not a therapeutic target of anti-Nogo-A immunotherapy, and contribute to our understanding of the SVZ response to cortical stroke.

Phosphodiesterase7 Inhibition Activates Adult Neurogenesis in Hippocampus and Subventricular Zone In Vitro and In Vivo.

The phosphodiesterase 7 (PDE7) enzyme is one of the enzymes responsible for controlling intracellular levels of cyclic adenosine 3',5'-monophosphate in the immune and central nervous system. We have previously shown that inhibitors of this enzyme are potent neuroprotective and anti-inflammatory agents. In addition, we also demonstrated that PDE7 inhibition induces endogenous neuroregenerative processes toward a dopaminergic phenotype. Here, we show that PDE7 inhibition controls stem cell expansion in the subgranular zone of the dentate gyrus of the hippocampus (SGZ) and the subventricular zone (SVZ) in the adult rat brain. Neurospheres cultures obtained from SGZ and SVZ of adult rats treated with PDE7 inhibitors presented an increased proliferation and neuronal differentiation compared to control cultures. PDE7 inhibitors treatment of neurospheres cultures also resulted in an increase of the levels of phosphorylated cAMP response element binding protein, suggesting that their effects were indeed mediated through the activation of the cAMP/PKA signaling pathway. In addition, adult rats orally treated with S14, a specific inhibitor of PDE7, presented elevated numbers of proliferating progenitor cells, and migrating precursors in the SGZ and the SVZ. Moreover, long-term treatment with this PDE7 inhibitor shows a significant increase in newly generated neurons in the olfactory bulb and the hippocampus. Also a better performance in memory tests was observed in S14 treated rats, suggesting a functional relevance for the S14-induced increase in SGZ neurogenesis. Taken together, our results indicate for the first time that inhibition of PDE7 directly regulates proliferation, migration and differentiation of neural stem cells, improving spatial learning and memory tasks. Stem Cells 2017;35:458-472.

The Effect of Pro-Neurogenic Gene Expression on Adult Subventricular Zone Precursor Cell Recruitment and Fate Determination After Excitotoxic Brain Injury

Despite the presence of on-going neurogenesis in the adult mammalian brain, neurons are generally not replaced after injury. Using a rodent model of excitotoxic cell loss and retroviral (RV) lineage tracing, we previously demonstrated transient recruitment of precursor cells from the subventricular zone (SVZ) into the lesioned striatum. In the current study we determined that these cells included migratory neuroblasts and oligodendrocyte precursor cells (OPC), with the predominant response from glial cells. We attempted to override this glial response by ectopic expression of the pro-neurogenic genes Pax6 or Dlx2 in the adult rat SVZ following quinolinic acid lesioning. RV-Dlx2 over-expression stimulated repair at a previously non-neurogenic time point by enhancing neuroblast recruitment and the percentage of cells that retained a neuronal fate within the lesioned area, compared to RV-GFP controls. RV-Pax6 expression was unsuccessful at inhibiting glial fate and intriguingly, increased OPC cell numbers with no change in neuronal recruitment. These findings suggest that gene choice is important when attempting to augment endogenous repair as the lesioned environment can overcome pro-neurogenic gene expression. Dlx2 over-expression however was able to partially overcome an anti-neuronal environment and therefore is a promising candidate for further study of striatal regeneration.

Graphene Functionalized Scaffolds Reduce the Inflammatory Response and Supports Endogenous Neuroblast Migration when Implanted in the Adult Brain.

Electroactive materials have been investigated as next-generation neuronal tissue engineering scaffolds to enhance neuronal regeneration and functional recovery after brain injury. Graphene, an emerging neuronal scaffold material with charge transfer properties, has shown promising results for neuronal cell survival and differentiation in vitro. In this in vivo work, electrospun microfiber scaffolds coated with self-assembled colloidal graphene, were implanted into the striatum or into the subventricular zone of adult rats. Microglia and astrocyte activation levels were suppressed with graphene functionalization. In addition, self-assembled graphene implants prevented glial scarring in the brain 7 weeks following implantation. Astrocyte guidance within the scaffold and redirection of neuroblasts from the subventricular zone along the implants was also demonstrated. These findings provide new functional evidence for the potential use of graphene scaffolds as a therapeutic platform to support central nervous system regeneration.

Leptin-dependent neurotoxicity via induction of apoptosis in adult rat neurogenic cells.

Adipocyte-derived hormone leptin has been recently implicated in the control of neuronal plasticity. To explore whether modulation of adult neurogenesis may contribute to leptin control of neuronal plasticity, we used the neurosphere assay of neural stem cells derived from the adult rat subventricular zone (SVZ). Endogenous expression of specific leptin receptor (ObRb) transcripts, as revealed by RT-PCR, is associated with activation of both ERK and STAT-3 pathways via phosphorylation of the critical ERK/STAT-3 amino acid residues upon addition of leptin to neurospheres. Furthermore, leptin triggered withdrawal of neural stem cells from the cell cycle as monitored by Ki67 labeling. This effect was blocked by pharmacological inhibition of ERK activation thus demonstrating that ERK mediates leptin effects on neural stem cell expansion. Leptin-dependent withdrawal of neural stem cells from the cell cycle was associated with increased apoptosis, as detected by TUNEL, which was preceded by cyclin D1 induction. Cyclin D1 was indeed extensively colocalized with TUNEL-positive, apoptotic nuclei. Cyclin-D1 silencing by specific shRNA prevented leptin-induced decrease of the cell number per neurosphere thus pointing to the causal relationship between leptin actions on apoptosis and cyclin D1 induction. Leptin target cells in SVZ neurospheres were identified by double TUNEL/phenotypic marker immunocytofluorescence as differentiating neurons mostly. The inhibition of neural stem cell expansion via ERK/cyclin D1-triggered apoptosis defines novel biological action of leptin which may be involved in adiposity-dependent neurotoxicity.

Neurogenic Potential Assessment and Pharmacological Characterization of 6-Methoxy-1,2,3,4-tetrahydro-β-carboline (Pinoline) and Melatonin-Pinoline Hybrids.

6-Methoxy-1,2,3,4-tetrahydro-β-carboline (pinoline) and N-acetyl-5-methoxytryptamine (melatonin) are both structurally related to 5-hydroxytryptamine (serotonin). Here we describe the design, synthesis, and characterization of a series of melatonin rigid analogues resulting from the hybridization of both pinoline and melatonin structures. The pharmacological evaluation of melatonin-pinoline hybrids comprises serotonergic and melatonergic receptors, metabolic enzymes (monoamine oxidases), antioxidant potential, the in vitro blood-brain barrier permeability, and neurogenic studies. Pinoline at trace concentrations and 2-acetyl-6-methoxy-1,2,3,4-tetrahydro-β-carboline (2) were able to stimulate early neurogenesis and neuronal maturation in an in vitro model of neural stem cells isolated from the adult rat subventricular zone. Such effects are presumably mediated via serotonergic and melatonergic stimulation, respectively.

A new and safe method for stereotactically harvesting neural stem/progenitor cells from the adult rat subventricular zone

Adult neural stem/progenitor cells (NS/PCs) are one of the outstanding cell sources for therapeutic purposes in the central nervous system diseases. Autologous transplantation of NS/PCs still is a matter of controversy due to the safety issue as well as efficiency of harvesting these cells from the live mammalian brain subventricular zone (SVZ). In this new and safe method, a 16-guage semi-automatic biopsy needle was used stereotactically to remove a piece of SVZ. Then, the proliferation and differentiation capacity of obtained cells were assessed. In addition, the safety of the biopsy procedure was analyzed employing the Morris water maze, modified neurologic severity score, passive avoidance and open field tests. Despite being very small in size, the SVZ specimen could generate a large number of progeny with the ability to differentiate into neuronal and glial cells. The biopsy procedure introduced in this study did not have any impact on the behavioral and neurological processes. existing SVZ biopsy methods were uncontrollable techniques which harvested brain tissue by aspiration using a syringe not a semi-automatic biopsy needle. Also, previous methods were not evaluated in terms of behavior and cognition. This study revealed a considerable safety and efficacy for the stereotactical removal of the adult rat SVZ to harvest NS/PCs for autologous transplantation.

Curcumin-Loaded Nanoparticles Potently Induce Adult Neurogenesis and Reverse Cognitive Deficits in Alzheimer’s Disease Model via Canonical Wnt/β-Catenin Pathway

Neurogenesis, a process of generation of new neurons, is reported to be reduced in several neurodegenerative disorders including Alzheimer's disease (AD). Induction of neurogenesis by targeting endogenous neural stem cells (NSC) could be a promising therapeutic approach to such diseases by influencing the brain self-regenerative capacity. Curcumin, a neuroprotective agent, has poor brain bioavailability. Herein, we report that curcumin-encapsulated PLGA nanoparticles (Cur-PLGA-NPs) potently induce NSC proliferation and neuronal differentiation in vitro and in the hippocampus and subventricular zone of adult rats, as compared to uncoated bulk curcumin. Cur-PLGA-NPs induce neurogenesis by internalization into the hippocampal NSC. Cur-PLGA-NPs significantly increase expression of genes involved in cell proliferation (reelin, nestin, and Pax6) and neuronal differentiation (neurogenin, neuroD1, neuregulin, neuroligin, and Stat3). Curcumin nanoparticles increase neuronal differentiation by activating the Wnt/β-catenin pathway, involved in regulation of neurogenesis. These nanoparticles caused enhanced nuclear translocation of β-catenin, decreased GSK-3β levels, and increased promoter activity of the TCF/LEF and cyclin-D1. Pharmacological and siRNA-mediated genetic inhibition of the Wnt pathway blocked neurogenesis-stimulating effects of curcumin. These nanoparticles reverse learning and memory impairments in an amyloid beta induced rat model of AD-like phenotypes, by inducing neurogenesis. In silico molecular docking studies suggest that curcumin interacts with Wif-1, Dkk, and GSK-3β. These results suggest that curcumin nanoparticles induce adult neurogenesis through activation of the canonical Wnt/β-catenin pathway and may offer a therapeutic approach to treating neurodegenerative diseases such as AD, by enhancing a brain self-repair mechanism.

Neuroglobin expression in neurogenesis

Neuroglobin is a hypoxia-inducible, neuroprotective protein related to myoglobin and hemoglobin, but little is known about its neurodevelopmental expression or function. To begin to explore these issues, we measured neuroglobin protein expression during neuronal differentiation of human embryonic stem cells in vitro and in the neurogenic subventricular zone of adult rats in vivo. Neuroglobin protein expression was barely detectable by western blotting in human embryonic stem cells, but was readily demonstrable in neural stem cells, and was further induced upon differentiation to neurons. In the adult subventricular zone, neuroglobin expression coincided with that of the neuronal lineage marker doublecortin, but not with vimentin or glial fibrillary acidic protein. These findings suggest that neuroglobin is expressed early in the course of neuronal differentiation and may, therefore, have a role in neurodevelopment.

Quercetin prevents protein nitration and glycolytic block of proliferation in hydrogen peroxide insulted cultured neuronal precursor cells (NPCs): Implications on CNS regeneration

Survival along with optimal proliferation of neuronal precursors determines the outcomes of the endogenous cellular repair in CNS. Cellular-oxidation based cell death has been described in several neurodegenerative disorders. Therefore, this study was aimed at the identification of the potent targets of oxidative damage to the neuronal precursors and its effective prevention by a natural flavonoid, Quercetin.Neuronal precursor cells (NPCs), Nestin+ and GFAP (Glial fibrillary acidic protein)+ were isolated and cultured from adult rat SVZ (subventricular zone). These cells were challenged with a single dose of H2O2 (50μM) and/or pre-treated with different concentrations of Quercetin. H2O2 severely limited the cellular viability and expansion of the neurospheres. Cellular-oxidation studies revealed reduction in glutathione dependent redox buffering along with depletion of enzymatic cellular antioxidants that might potentiate the nitrite (NO2−) and superoxide anion (O2−) mediated peroxynitrite (ONOO−) formation and irreversible protein nitration. We identified depleted PK-M2 (M2 isoform of pyruvate kinase) activity and apoptosis of NPCs revealed by the genomic DNA fragmentation and elevated PARP (poly ADP ribose polymerase) activity along with increased Caspase activity initiated by severely depolarised mitochondrial membranes. However, the pre-treatment of Quercetin in a dose–response manner prevented these changes and restored the expansion of neurospheres preferably by neutralizing the oxidative conditions and thereby reducing peroxynitrite formation, protein nitration and PK-M2 depletion.Our results unravel the potential interactions of oxidative environment and respiration in the survival and activation of precursors and offer a promise shown by a natural flavonoid in the protective strategy for neuronal precursors of adult brain.

Rapid Transgene Expression in Multiple Precursor Cell Types of Adult Rat Subventricular Zone Mediated by Adeno-Associated Type 1 Vectors

The adult rat brain subventricular zone (SVZ) contains proliferative precursors that migrate to the olfactory bulb (OB) and differentiate into mature neurons. Recruitment of precursors constitutes a potential avenue for brain repair. We have investigated the kinetics and cellular specificity of transgene expression mediated by AAV2/1 vectors (i.e., adeno-associated virus type 2 pseudotyped with AAV1 capsid) in the SVZ. Self-complementary (sc) and single-stranded (ss) AAV2/1 vectors mediated efficient GFP expression, respectively, at 17 and 24 hr postinjection. Transgene expression was efficient in all the rapidly proliferating cells types, that is, Mash1(+) precursors (30% of the GFP(+) cells), Dlx2(+) neuronal progenitors (55%), Olig2(+) oligodendrocyte progenitors (35%), and doublecortin-positive (Dcx(+)) migrating cells (40%), but not in the slowly proliferating glial fibrillary acidic protein-positive (GFAP(+)) neural stem cell pool (5%). Because cell cycle arrest by wild-type and recombinant AAV has been described in primary cultures, we examined SVZ proliferative activity after vector injection. Indeed, cell proliferation was reduced immediately after vector injection but was normal after 1 month. In contrast, migration and differentiation of GFP(+) precursors were unaltered. Indeed, the proportion of Dcx(+) cells was similar in the injected and contralateral hemispheres. Furthermore, 1 month after vector injection into the SVZ, GFP(+) cells, found, as expected, in the OB granular cell layer, were mature GABAergic neurons. In conclusion, the rapid and efficient transgene expression in SVZ neural precursors mediated by scAAV2/1 vectors underlines their potential usefulness for brain repair via recruitment of immature cells. The observed transient precursor proliferation inhibition, not affecting their migration and differentiation, will likely not compromise this strategy.

161. Rapid Transgene Expression in Multiple Precursors Cell Types of Adult Rat Subventricular Zone Mediated by Adeno-Associated Type 1 Vectors

161. Rapid Transgene Expression in Multiple Precursors Cell Types of Adult Rat Subventricular Zone Mediated by Adeno-Associated Type 1 Vectors

Rapid Transgene Expression in Multiple Precursor Cell Types of Adult Rat Subventricular Zone Mediated by Adeno-Associated Type 1 Vectors

Rapid Transgene Expression in Multiple Precursor Cell Types of Adult Rat Subventricular Zone Mediated by Adeno-Associated Type 1 Vectors

Chemokines influence the migration and fate of neural precursor cells from the young adult and middle-aged rat subventricular zone

We have previously demonstrated a role for the chemokines MCP-1, MIP-1α and GRO-α in directing subventricular zone (SVZ)-derived neural precursor cell migration towards the site of cell death in the adult rodent brain. However the influence of chemokines such as MCP-1, MIP-1α and GRO-α on the differentiation of adult neural precursor cells has not previously been investigated. Further, as the majority of neurological disorders and injuries occur during ageing, it is important to investigate the effect of chemokines on adult neural precursor cell cultures obtained from the ageing brain. This study therefore examined the effect of MCP-1, MIP-1α and GRO-α on SVZ-derived neural precursor cell differentiation in vitro, and assessed whether precursor cells from the middle-aged rat brain (13months old) follow the same migratory and differential profile as neural precursor cells obtained from the young adult rat brain (2months old). We observed that each of the chemokines examined generated differing effects in regards to neuronal or glial differentiation. Further, both MIP-1α and GRO-α increased total cell number, suggesting an effect on precursor cell proliferation and/or survival. In agreement with cultures obtained from young adult brains, SVZ-derived neural precursor cells cultured from the middle-aged brain exhibited chemotactic migration in response to a concentration gradient. These results indicate that the chemokines MCP-1, MIP-1α and GRO-α can influence both the migration and fate choice of SVZ-derived neural precursor cells, as well as promoting cell viability. While a response to each of these chemokines is maintained in the middle-aged brain, a distinct age-related alteration in differential fate can be identified.

Treatment with edaravone attenuates ischemic brain injury and inhibits neurogenesis in the subventricular zone of adult rats after focal cerebral ischemia and reperfusion injury

Edaravone is a novel free radical scavenger that is clinically employed in patients with acute cerebral infarction. However, its effect on stroke-induced subventricular zone (SVZ) neurogenesis is largely unknown. In this study, we investigated the effect and underlying mechanism of edaravone administration on SVZ neurogenesis using a rat model of cerebral ischemia-reperfusion injury. Male Sprague–Dawley rats (200–250 g) were divided into sham operated ( n=15), control ( n=50), and edaravone-treated ( n=50) groups. Rats in the control and edaravone-treated groups underwent 90 min of middle cerebral artery occlusion (MCAO) following reperfusion. Immediately and 12 h after MCAO, the rats received either normal saline (control group) or edaravone (edaravone-treated group) intraperitoneally. 5-bromo-2-deoxyuridine (BrdU) was used to label proliferating cells. Six, 12, and 24 hours after ischemia, reactive oxygen species (ROS) generation, hypoxia-inducible factor 1α (HIF-1α), and vascular endothelial growth factor (VEGF) protein levels in ischemic ipsilateral SVZ were determined. Immunohistochemistry staining for BrdU and doublecortin (DCX) was performed at 1, 4, and 7 days after ischemia. Treatment with edaravone not only mitigated cerebral infarct size ( P<0.05) and neurological defects ( P<0.05), but also decreased cell proliferation and neural progenitor cells in the ischemic ipsilateral SVZ ( P<0.05). Additionally, edaravone reduced effectively ROS generation and HIF-1α as well as VEGF protein levels in the ischemic ipsilateral SVZ ( P<0.05). These findings indicate that administration with edaravone, via repressing HIF-1α signaling pathway, inhibits SVZ neurogenesis in rats after cerebral ischemia-reperfusion injury.

MicroRNA Profiling in Subventricular Zone after Stroke: MiR-124a Regulates Proliferation of Neural Progenitor Cells through Notch Signaling Pathway

BackgroundThe Notch signaling pathway regulates adult neurogenesis under physiological and pathophysiological conditions. MicroRNAs are small non-coding RNA molecules that regulate gene expression. The present study investigated the effect of miR-124a on the Notch signaling pathway in stroke-induced neurogenesis.Methodology and Principal FindingsWe found that adult rats subjected to focal cerebral ischemia exhibited substantial reduction of miR-124a expression, a neuron specific miRNA, in the neural progenitor cells of the subventricular zone (SVZ) of the lateral ventricle, which was inversely associated with activation of Notch signals. In vitro, transfection of neural progenitor cells harvested from the SVZ of adult rat with miR-124a repressed Jagged-1 (JAG1), a ligand of Notch, in a luciferase construct containing the JAG1 target site. Introduction of miR-124a in neural progenitor cells significantly reduced JAG1 transcript and protein levels, leading to inactivation of Notch signals. Transfection of neural progenitor cells with miR-124a significantly reduced progenitor cell proliferation and promoted neuronal differentiation measured by an increase in the number of Doublecortin positive cells, a marker of neuroblasts. Furthermore, introduction of miR-124a significantly increased p27Kip1 mRNA and protein levels, a downstream target gene of the Notch signaling pathway.ConclusionsCollectively, our study demonstrated that in vivo, stroke alters miRNA expression in SVZ neural progenitor cells and that in vitro, miR-124a mediates stroke-induced neurogenesis by targeting the JAG-Notch signaling pathway.