Targeting Glial Mitochondrial Function for Protection from Cerebral Ischemia: Relevance, Mechanisms, and the Role of MicroRNAs

Inhibition of microRNA-200c preserves astrocyte sirtuin-1 and mitofusin-2, and protects against hippocampal neurodegeneration following global cerebral ischemia in mice

Memory impairment remains a leading disability in survivors of global cerebral ischemia, occurring secondary to delayed neurodegeneration of hippocampal cornu ammonis-1 (CA1) neurons. MicroRNA-200c (miR-200c) is induced following ischemic stress and we have previously demonstrated that pre-treatment with anti-miR-200c is protective against embolic stroke in mice. In the present study we assessed the role of miR-200c on CA1 neurodegeneration, sirtuin-1 (SIRT1), and mitochondrial dynamic protein expression in a mouse model of transient global cerebral ischemia and in vitro in primary mouse astrocyte cultures after simulated ischemia. Mice were subjected to 10 min bilateral common carotid artery occlusion plus hypotension with 5% isoflurane. After 2 h recovery mice were treated with intravenous injection of either anti-miR-200c or mismatch control. Memory function was assessed by Barnes maze at post-injury days 3 and 7. Mice were sacrificed at post-injury day 7 for assessment of brain cell-type specific expression of miR-200c, SIRT1, and the mitochondrial fusion proteins mitofusin-2 (MFN2) and OPA1 via complexed fluorescent in situ hybridization and fluorescent immunohistochemistry. Global cerebral ischemia induced significant loss of CA1 neurons, impaired memory performance and decreased expression of CA1 SIRT1, MFN2, and OPA1. Post-injury treatment with anti-miR-200c significantly improved survival, prevented CA1 neuronal loss, improved post-injury performance in Barnes maze, and was associated with increased post-injury expression of CA1 SIRT1 and MFN2 in astrocytes. In vitro, primary mouse astrocyte cultures pre-treated with miR-200c inhibitor prior to oxygen/glucose deprivation preserved expression of SIRT1 and MFN2, and decreased reactive oxygen species generation, whereas pre-treatment with miR-200c mimic had opposite effects that could be reversed by co-treatment with SIRT1 activator. These results suggest that miR-200c regulates astrocyte mitochondrial homeostasis via targeting SIRT1, and that CA1 astrocyte mitochondria and SIRT1 represent potential post-injury therapeutic targets to preserve cognitive function in survivors of global cerebral ischemia.

Glycogen synthase kinase-3β inhibition decreases inflammation and relieves cancer induced bone pain via reducing Drp1-mediated mitochondrial damage

Bone is the preferential site of metastasis for breast cancer. Invasion of cancer cells induces the destruction of bone tissue and damnification of peripheral nerves and consequently induced central sensitization which contributes to severe pain. Herein, cancer induced bone pain (CIBP) rats exhibited destruction of tibia, mechanical allodynia and spinal inflammation. Inflammatory response mainly mediated by astrocyte and microglia in central nervous system. Our immunofluorescence analysis revealed activation of spinal astrocytes and microglia in CIBP rats. Transmission electron microscopy (TEM) observations of mitochondrial outer membrane disruption and cristae damage in spinal mitochondria of CIBP rats. Proteomics analysis identified abnormal expression of proteins related to mitochondrial organization and function. Intrathecally, injection of GSK‐3β activity inhibitor TDZD‐8 significantly attenuated Drp1‐mediated mitochondrial fission and recovered mitochondrial function. Inhibition of GSK‐3β activity also suppressed NLRP3 inflammasome cascade and consequently decreased mechanical pain sensitivity of CIBP rats. For cell research, TDZD‐8 treatment significantly reversed TNF‐α induced mitochondrial membrane potential (MMP) deficiency and high mitochondrial reactive oxygen species level. Taken together, GSK‐3β inhibition by TDZD‐8 decreases spinal inflammation and relieves cancer induced bone pain via reducing Drp1‐mediated mitochondrial damage.

Placental miRNAs Targeting Cellular Stress Response Pathways Are Highly Expressed in Non-Hispanic Black People

Non-Hispanic Black (NHB) people have a 2.5-fold higher risk of maternal mortality when compared to non-Hispanic White (NHW) people. Neonates of NHB people are more likely to be born preterm and small for gestational age, which may be driven by structural racism. The placenta is very sensitive to the maternal environment and may play a critical role in the translation of environmental stressors to pregnancy outcomes. Our aim was to assess the placental miRNA expression profile in both NHB and NHW people and the association between differentially expressed miRNAs and pregnancy outcomes. Placentas were collected from 50 NHB and 74 NHW people with a normal singleton pregnancy undergoing elective cesarean section at term prior to the onset of labor. Placental miRNA expression was measured via whole-genome small RNA-sequencing in a subset of 77 placentas. Fifteen miRNAs were more highly expressed in the placentas of NHB people. Several of these miRNAs were associated with cellular stress response pathways, suggesting that they may be responding to environmental stressors. Placental miR-192-5p expression was lower among NHB people and was positively associated with neonatal adiposity, suggesting it may be sensitive to structural racism with potential impacts on fetal growth.

Mitochondrial Quality Control in Cerebral Ischemia-Reperfusion Injury

Ischemic stroke is one of the leading causes of death and also a major cause of adult disability worldwide. Revascularization via reperfusion therapy is currently a standard clinical procedure for patients with ischemic stroke. Although the restoration of blood flow (reperfusion) is critical for the salvage of ischemic tissue, reperfusion can also, paradoxically, exacerbate neuronal damage through a series of cellular alterations. Among the various theories postulated for ischemia/reperfusion (I/R) injury, including the burst generation of reactive oxygen species (ROS), activation of autophagy, and release of apoptotic factors, mitochondrial dysfunction has been proposed to play an essential role in mediating these pathophysiological processes. Therefore, strict regulation of the quality and quantity of mitochondria via mitochondrial quality control is of great importance to avoid the pathological effects of impaired mitochondria on neurons. Furthermore, timely elimination of dysfunctional mitochondria via mitophagy is also crucial to maintain a healthy mitochondrial network, whereas intensive or excessive mitophagy could exacerbate cerebral I/R injury. This review will provide a comprehensive overview of the effect of mitochondrial quality control on cerebral I/R injury and introduce recent advances in the understanding of the possible signaling pathways of mitophagy and potential factors responsible for the double-edged roles of mitophagy in the pathological processes of cerebral I/R injury.

Coding and non-coding nucleotides': The future of stroke gene therapeutics

Stroke is the foremost cause of death ranked after heart disease and cancer. It is the fatal life-threatening event that requires immediate medical admissions to overcome following morbidity and mortality. The therapeutic advances in stroke therapy have been manipulated with diverse paths for last 5 years. Recent research and clinical trials have investigated a variety of anti-stroke agents including anti-coagulants, cerebro-protective agents, antiplatelet therapy, stem-cell therapy, and specified gene therapy. In recent advanced studies, genetic therapies including noncoding RNAs (ncRNAs), long non-coding RNAs (LncRNAs), small interfering RNAs (siRNAs), microRNAs (miRNAs), Piwi interacting RNAs (PiWi RNAs) have shown better potential as targeted future therapeutics with a better outcome than conventional stroke therapeutics. The potential of targeted gene therapy is much more advanced in not only the induction of neuroprotection but also safer non-toxic targeted therapeutics. In the current state of the art review, we have focused on the recent advancements made towards the stroke with RNA modifications and targeted gene therapeutics.

β-Alanine Supplementation Attenuates the Neurophysiological Response in Animals Exposed to an Acute Heat Stress

The effect of 30 days of β-alanine supplementation on neurophysiological responses of animals exposed to an acute heat stress (HS) was examined. Animals were randomized to one of three groups; exposed to HS (120 min at 40-41 °C) and fed a normal diet (EXP; n = 12); EXP and supplemented with β-alanine (EXP + BA; n = 10); or not exposed (CTL; n = 10). Hippocampal (CA1, CA3 and DG) and hypothalamic (PVN) immunoreactive (ir) cell numbers of COX2, IBA-1, BDNF, NPY and HSP70 were analyzed. Three animals in EXP and one in EXP-BA did not survive the HS, however no significant difference (p = 0.146) was noted in survival rate in EXP + BA. The % change in rectal temperature was significantly lower (p = 0.04) in EXP + BA than EXP. Elevations (p's < 0.05) in COX-2, IBA-1 and HSP70 ir-cell numbers were noted in animals exposed to HS in all subregions. COX-2 ir-cell numbers were attenuated for EXP + BA in CA1 (p = 0.02) and PVN (p = 0.015) compared to EXP. No difference in COX-2 ir-cell numbers was noted between CTL and EXP + BA at CA1. BDNF-ir cell numbers in CA1, DG and PVN were reduced (p's < 0.05) during HS compared to CTL. No difference in BDNF-ir cell numbers was noted between EXP + BA and CTL in CA3 and PVN. NPY-ir density was reduced in exposed animals in all subregions, but NPY-ir density for EXP-BA was greater than EXP in CA3 (p < 0.001) and PVN (p = 0.04). β-Alanine supplementation attenuated the thermoregulatory and inflammatory responses and maintained neurotrophin and neuropeptide levels during acute HS. Further research is necessary to determine whether β-alanine supplementation can increase survival rate during a heat stress.

The Role of Mitophagy in Ischemic Stroke

Mitochondria are important places for eukaryotes to carry out energy metabolism and participate in the processes of cell differentiation, cell information transmission, and cell apoptosis. Autophagy is a programmed intracellular degradation process. Mitophagy, as a selective autophagy, is an evolutionarily conserved cellular process to eliminate dysfunctional or redundant mitochondria, thereby fine-tuning the number of mitochondria and maintaining energy metabolism. Many stimuli could activate mitophagy to regulate related physiological processes, which could ultimately reduce or aggravate the damage caused by stimulation. Stroke is a common disease that seriously affects the health and lives of people around the world, and ischemic stroke, which is caused by cerebral vascular stenosis or obstruction, accounts for the vast majority of stroke. Abnormal mitophagy is closely related to the occurrence, development and pathological mechanism of ischemic stroke. However, the exact mechanism of mitophagy involved in ischemic stroke has not been fully elucidated. In this review, we discuss the process and signal pathways of mitophagy, the potential role of mitophagy in ischemic stroke and the possible signal transduction pathways. It will help deepen the understanding of mitophagy and provide new ideas for the treatment of ischemic stroke.

miR-22 protect PC12 from ischemia/reperfusion-induced injury by targeting p53 upregulated modulator of apoptosis (PUMA)

MicroRNAs have been implicated as critical regulatory molecules in many cerebrovascular diseases. Recent studies demonstrated miR-22 might provide a potential neuroprotective effect. However, the neuroprotective effect of miR-22 in ischemia/reperfusion (I/R) injury has not been thoroughly elucidated. In this study, the PC12 cells were subjected to 4 h oxygen and glucose deprivation (I) and 24 h reoxygenation (R). The PC12 cells were pre-transfected with miR-22 or anti-miR-22 or siRNA-mediated downregulation of p53-upregulated-modulator-of-apoptosis (PUMA)(PUMA siRNA) or their controls at 24 h prior to exposure to I/R. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot were employed to analyze mRNA and protein expression. PI and Annexin V assays and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assay were used to quantify the rate of apoptosis. We found that miR-22 expression was significantly downregulated in the PC12 cells subjected to I/R. Loss of function of miR-22 increased PC12 apoptosis after I/R, and overexpression of miR-22 decreases PC12 apoptosis after I/R. PUMA protein was upregulated in the I/R group as compared with the sham group. The increased PUMA protein expression and apoptosis induced by I/R was reversed by transfection with PUMA siRNA. We concluded that I/R enhanced apoptosis and PUMA expression in PC12 cells via downregulation of miR-22. Enhanced miR-22 expression reversed both PUMA expression and apoptosis induced by I/R in PC12 cells. miR-22/PUMA axis has important implications for their clinical applications.

The role of astrocytes in oxidative stress of central nervous system: A mixed blessing

Central nervous system (CNS) maintains a high level of metabolism, which leads to the generation of large amounts of free radicals, and it is also one of the most vulnerable organs to oxidative stress. Emerging evidences have shown that, as the key homeostatic cells in CNS, astrocytes are deeply involved in multiple aspects of CNS function including oxidative stress regulation. Besides, the redox level in CNS can in turn affect astrocytes in morphology and function. The complex and multiple roles of astrocytes indicate that their correct performance is crucial for the normal functioning of the CNS, and its dysfunction may result in the occurrence and progression of various neurological disorders. To date, the influence of astrocytes in CNS oxidative stress is rarely reviewed. Therefore, in this review we sum up the roles of astrocytes in redox regulation and the corresponding mechanisms under both normal and different pathological conditions.

Adult neurogenesis from reprogrammed astrocytes

The details of adult neurogenesis, including environmental triggers, region specificity, and species homology remain an area of intense investigation. Slowing or halting age-related cognitive dysfunction, or restoring neurons lost to disease or injury represent just a fraction of potential therapeutic applications. New neurons can derive from stem cells, pluripotent neural progenitor cells, or non-neuronal glial cells, such as astrocytes. Astrocytes must be epigenetically “reprogrammed” to become neurons, which can occur both naturally in vivo, and via artificial exogenous treatments. While neural progenitor cells are localized to a few neurogenic zones in the adult brain, astrocytes populate almost every brain structure. In this review, we will summarize recent research into neurogenesis that arises from conversion of post-mitotic astrocytes, detail the genetic and epigenetic pathways that regulate this process, and discuss the possible clinical relevance in supplementing stem-cell neurogenic therapies.

Therapeutic use of extracellular mitochondria in CNS injury and disease

In the central nervous system (CNS), neuronal functionality is highly dependent on mitochondrial integrity and activity. In the context of a damaged or diseased brain, mitochondrial dysfunction leads to reductions in ATP levels, thus impairing ATP-dependent neural firing and neurotransmitter dynamics. Restoring mitochondrial ability to generate ATP may be a basic premise to restore neuronal functionality. Recently, emerging data in rodent and human studies suggest that mitochondria and its components are surprisingly released into extracellular space and potentially transferred between cells. Transferred mitochondria may support oxidative phosphorylation in recipient cells. In this mini-review, we (a) survey recent findings in cell to cell mitochondrial transfer and the presence of cell-free extracellular mitochondria and its components, (b) review experimental details of how to detect extracellular mitochondria and mitochondrial transfer in the CNS, (c) discuss strategies and tissue sources for mitochondria isolation, and (d) explore exogenous mitochondrial transplantation as a novel approach for CNS therapies.

Postinjury Inhibition of miR-181a Promotes Restoration of Hippocampal CA1 Neurons after Transient Forebrain Ischemia in Rats

The cellular and molecular mechanisms regulating postinjury neurogenesis in the adult hippocampus remain undefined. We have previously demonstrated that preinjury treatment with anti-microRNA (miR)-181a preserved neurons and prevented astrocyte dysfunction in the hippocampal cornu ammonis-1 (CA1) following transient forebrain ischemia. In the present study, we assessed postinjury treatment with anti-miR-181a on recovery of CA1 neurons following transient forebrain ischemia in rats. Stereotactic CA1 injection of miR-181a antagomir at either 2 h or 7 d postinjury resulted in improved restoration of CA1 measured at 28 d postinjury. Treatment with antagomir was associated with overexpression of the mir-181a target cell adhesion-associated, oncogene-related protein and enhanced expression of the neuroprogenitor cell marker doublecortin (DCX) in the CA1. Assessment of GFAP+ cell fate by Cre/Lox-mediated deletion demonstrated that some GFAP+ cells in CA1 exhibited de novo DCX expression in response to injury. In vitro experiments using primary neuronal stem cells confirmed that miR-181a inhibition augmented the expression of DCX and directed cellular differentiation toward a neuronal fate. These results suggest that miR-181a inhibition plays a central role in the restoration of CA1 neurons via augmentation of early latent neurogenic gene activation in neural progenitor cells, including some reactive astrocytes. Therapeutic interventions targeting this restorative process may represent a novel postinjury approach to improve clinical outcomes in survivors of forebrain ischemia.

MicroRNAs in brain development and cerebrovascular pathophysiology

MicroRNAs (miRNAs) are a class of highly conserved non-coding RNAs with 21-25 nucleotides in length and play an important role in regulating gene expression at the posttranscriptional level via base-paring with complementary sequences of the 3'-untranslated region of the target gene mRNA, leading to either transcript degradation or translation inhibition. Brain-enriched miRNAs act as versatile regulators of brain development and function, including neural lineage and subtype determination, neurogenesis, synapse formation and plasticity, neural stem cell proliferation and differentiation, and responses to insults. Herein, we summarize the current knowledge regarding the role of miRNAs in brain development and cerebrovascular pathophysiology. We review recent progress of the miRNA-based mechanisms in neuronal and cerebrovascular development as well as their role in hypoxic-ischemic brain injury. These findings hold great promise, not just for deeper understanding of basic brain biology but also for building new therapeutic strategies for prevention and treatment of pathologies such as cerebral ischemia.

Effect of Inflammation on the Process of Stroke Rehabilitation and Poststroke Depression

A considerable body of evidence has shown that inflammation plays an important role in the process of stroke rehabilitation and development of poststroke depression (PSD). However, the specific molecular and cellular mechanisms involved remain unclear. In this review, we summarize how neuroinflammation affects stroke rehabilitation and PSD. We mainly focus on the immune/inflammatory response, involving astrocytes, microglia, monocyte-derived macrophages, cytokines (tumor necrosis factor alpha, interleukin 1), and microRNAs (microRNA-124, microRNA 133b). This review provides new insights into the effect of inflammation on the process of stroke rehabilitation and PSD and potentially offer new therapeutic targets of stroke and PSD.

The Role of MicroRNAs in Environmental Risk Factors, Noise-Induced Hearing Loss, and Mental Stress

SIGNIFICANCE

MicroRNAs (miRNAs) are important regulators of gene expression and define part of the epigenetic signature. Their influence on every realm of biomedicine is established and progressively increasing. The impact of environment on human health is enormous. Among environmental risk factors impinging on quality of life are those of chemical nature (toxic chemicals, heavy metals, pollutants, and pesticides) as well as those related to everyday life such as exposure to noise or mental and psychosocial stress. Recent Advances: This review elaborates on the relationship between miRNAs and these environmental risk factors.

CRITICAL ISSUES

The most relevant facts underlying the role of miRNAs in the response to these environmental stressors, including redox regulatory changes and oxidative stress, are highlighted and discussed. In the cases wherein miRNA mutations are relevant for this response, the pertinent literature is also reviewed.

FUTURE DIRECTIONS

We conclude that, even though in some cases important advances have been made regarding close correlations between specific miRNAs and biological responses to environmental risk factors, a need for prospective large-cohort studies is likely necessary to establish causative roles. Antioxid. Redox Signal. 28, 773-796.

Protective effects of paeonol on subacute/chronic brain injury during cerebral ischemia in rats

Ischemic stroke is a highly complex pathological process that is divided into acute, subacute and chronic phases. Paeonol is a biologically active natural product with a variety of pharmacological effects, including those on neuronal activity. However, the effects of paeonol on subacute/chronic ischemic stroke have remained to be elucidated. The present study was designed to investigate the effects of paeonol against subacute and chronic cerebral ischemic injury and to explore the possible underlying mechanisms. Male adult Sprague Dawley rats were randomly divided into a sham group (treated with saline), a model group [subjected to middle cerebral artery occlusion (MCAO) and treated with saline] and a paeonol-treated group (MCAO + paeonol at 25 mg/kg). Behavioral impairment, infarct volume and ischemic/contralateral hemispheric ratios were assessed at 72 h and at 28 days after MCAO, respectively. Immunofluorescence was employed to determine the neuronal damage and glial responses after MCAO. Compared with the model group, paeonol treatment significantly attenuated behavioral impairment, ischemic infarct volume and moderate cerebral edema in the ischemic brain at 72 h, as well as brain atrophy at 28 days after reperfusion. Furthermore, paeonol treatment ameliorated neuronal damage in the ischemic core and boundary zone regions at 72 h after reperfusion and in the boundary zone at 28 days after reperfusion. In addition, paeonol treatment reduced the proliferation of astrocytes in the boundary zone, and inhibited microglial activation in the ischemic core and boundary zone regions at 72 h and 28 days after reperfusion. These results demonstrated the protective effects of paeonol against subacute/chronic cerebral ischemia, and the mechanism of action may include subacute/chronic microglial activation and astrocyte proliferation.

Sexually Dimorphic Outcomes after Neonatal Stroke and Hypoxia-Ischemia

Cohort studies have demonstrated a higher vulnerability in males towards ischemic and/or hypoxic-ischemic injury in infants born near- or full-term. Male sex was also associated with limited brain repair following neonatal stroke and hypoxia-ischemia, leading to increased incidence of long-term cognitive deficits compared to females with similar brain injury. As a result, the design of pre-clinical experiments considering sex as an important variable was supported and investigated because neuroprotective strategies to reduce brain injury demonstrated sexual dimorphism. While the mechanisms underlining these differences between boys and girls remain unclear, several biological processes are recognized to play a key role in long-term neurodevelopmental outcomes: gonadal hormones across developmental stages, vulnerability to oxidative stress, modulation of cell death, and regulation of microglial activation. This review summarizes the current evidence for sex differences in neonatal hypoxic-ischemic and/or ischemic brain injury, considering the major pathways known to be involved in cognitive and behavioral deficits associated with damages of the developing brain.

MicroRNA expression changes in association with changes in interleukin-1ß/interleukin10 ratios produced by monocytes in autism spectrum disorders: their association with neuropsychiatric symptoms and comorbid conditions (observational study)

BACKGROUND

MicroRNAs (miRNAs) play a major role in regulating immune responses at post-transcriptional levels. Previously, we have reported fluctuating interlukine-1ß (IL-1ß)/IL-10 ratios produced by peripheral blood monocytes (PBMo) in some patients with autism spectrum disorders (ASD). This study examined whether changes in miRNA expression by PBMo are associated with changes in IL-1ß/IL-10 ratios and how such changes are associated with ASD clinical features.

METHODS

miRNA expression by purified PBMo from ASD subjects (N = 69) and non-ASD controls (N = 27) were determined by high-throughput sequencing. Cytokine production by PBMo in responses to stimuli of innate immunity, and behavioral symptoms [assessed by aberrant behavioral checklist (ABC)] were also evaluated at the same time of sample obtainment.

RESULTS

As a whole, there was no difference in miRNA expression between ASD and control non-ASD PBMo. However, when ASD cells were subdivided into 3 groups with high, normal, or low IL-1ß/IL-10 ratios as defined in the "Results" section, in comparison with the data obtained from non-ASD controls, we observed marked changes in miRNA expression. Namely, over 3-fold changes in expression of miR-181a, miR-93, miR-223, miR-342, and miR-1248 were observed in ASD PBMo with high or low IL-1ß/IL-10 ratios, but not in ASD PBMo with normal ratios. These miRNAs that had altered in expression are those closely associated with the regulation of key signaling pathways. With changes in IL-1ß/IL-10 ratios, we also observed changes in the production of cytokines (IL-6, TNF-α, and TGF-ß) other than IL-1ß/IL-10 by ASD PBMo. The association between behavioral symptoms and cytokine levels was different when ASD cells exhibit high/low IL-1ß/IL-10 ratios vs. when ASD cells exhibited normal ratios. Non-IgE-mediated food allergy was also observed at higher frequency in ASD subjects with high/low IL-1ß/IL-10 ratios than with normal ratios.

CONCLUSIONS

Changes in cytokine profiles and miRNA expression by PBMo appear to be associated with changes in ASD behavioral symptoms. miRNAs that are altered in expression in ASD PBMo with high/low IL-1ß/IL-10 ratios are those associated with inflammatory responses. Changes in IL-1ß/IL-10 ratios along with changes in miRNA expression may serve as biomarkers for immune-mediated inflammation in ASD.

MicroRNA-29b alleviates oxygen and glucose deprivation/reperfusion-induced injury via inhibition of the p53-dependent apoptosis pathway in N2a neuroblastoma cells

Cerebral ischemic injury causes severe brain damage and remains one of the leading causes of morbidity and mortality worldwide. Members of the microRNA-29 (miR-29) family are involved in regulating the process of ischemia and may be developed as biomarkers to diagnose and treat cerebral ischemia. The role of miR-29b in cerebral ischemia injury remains poorly understood. The purpose of the present study was to investigate whether miR-29b overexpression suppressed cerebral ischemic injury and to explore its underlying mechanism of action. The results demonstrated that levels of miR-29b in N2a neuroblastoma cells decreased following oxygen and glucose deprivation/reperfusion (OGD/R) treatment. Transfection with miR-29b mimics significantly increased cell viability, decreased lactate dehydrogenase (LDH) leakage, inhibited apoptosis by decreasing morphological changes occurring in the nuclei and reduced caspase-3 activity in OGD/R-treated N2a cells. Conversely, miR-29b inhibitors enhanced OGD/R-induced cytotoxicity and apoptosis. In addition, the miR-29b mimics blocked the increase in Bax and p53 expression and decreased Bcl-2 expression in OGD/R-treated N2a cells, whereas miR-29b inhibitors exacerbated the changes in the expression of these apoptosis-associated proteins caused by OGD/R. p53 knockdown using p53 small interfering RNA decreased cell viability and increased LDH leakage, reversing the improvements that the miR-29b mimics induced in damaged cells. Taken together, the results of the present study demonstrated that miR-29b attenuates ischemic injury by negatively regulating the p53-dependent apoptosis pathway and may therefore be a novel potential therapeutic target for treating ischemic stroke.