Project description:Migroglia cells were exposed to oxygen-glucose deprivation (OGD) for 3 h. The miRNA was isolated and the expression profiles of OGD-activated cells were compared with the profiles of resting cells. Two samples were analysed. miRNAs that were differentially expressed (increased or decreased in expression by â¥1.5-fold) between theOGD-activated and resting cells were identified.
Project description:Migroglia cells were exposed to oxygen-glucose deprivation (OGD) for 3 h. The miRNA was isolated and the expression profiles of OGD-activated cells were compared with the profiles of resting cells.
Project description:Migroglia cells were exposed to oxygen-glucose deprivation (OGD) for 3 h. The mRNA was isolated and the expression profiles of OGD-activated cells were compared with the profiles of resting cells.
Project description:Brain-resident microglia may promote tissue repair following stroke but, like other cells, they are vulnerable to ischemia. Here we identify mechanisms involved in microglial ischemic vulnerability. Using time-lapse imaging of cultured BV2 microglia, we show that simulated ischemia (oxygen-glucose deprivation; OGD) induces BV2 microglial cell death. Removal of extracellular Ca(2+) or application of Brilliant Blue G (BBG), a potent P2X7 receptor (P2X7R) antagonist, protected BV2 microglia from death. To validate and extend these in vitro findings, we assessed parenchymal microglia in freshly isolated hippocampal tissue slices from GFP-reporter mice (CX3CR1(GFP/+)). We confirmed that calcium removal or application of apyrase, an ATP-degrading enzyme, abolished OGD-induced microglial cell death in situ, consistent with involvement of ionotropic purinergic receptors. Indeed, whole cell recordings identified P2X7R-like currents in tissue microglia, and OGD-induced microglial cell death was inhibited by BBG. These pharmacological results were complemented by studies in tissue slices from P2X7R null mice, in which OGD-induced microglia cell death was reduced by nearly half. Together, these results indicate that stroke-like conditions induce calcium-dependent microglial cell death that is mediated in part by P2X7R. This is the first identification of a purinergic receptor regulating microglial survival in living brain tissues. From a therapeutic standpoint, these findings could help direct novel approaches to enhance microglial survival and function following stroke and other neuropathological conditions.
Project description:Hyperchloremia and hypernatremia are associated with higher mortality in ischemic stroke, but it remains unclear whether their influence directly contributes to ischemic injury. We investigated the impact of 0.9% sodium chloride (154 mM NaCl), 0.9% sodium acetate (167 mM CH3COONa), and their different combinations (3:1, 2:1, and 1:1) on microglial (HMC-3) and neuronal (differentiated SH-SY5Y) survival during oxygen-glucose deprivation/reperfusion (OGD/R). Further, we assessed the effect of hyperchloremia and hypernatremia-treated and OGD/R-induced HMC-3-conditioned media on differentiated SH-SY5Y cells under OGD/R conditions. We performed cell viability, cell toxicity, and nitric oxide (NO) release assays and studied the alteration in expression of caspase-1 and caspase-3 in different cell lines when exposed to hyperchloremia and hypernatremia. Cell survival was decreased in 0.9% NaCl, 0.9% CH3COONa, combinations of HMC-3 and differentiated SH-SY5Y, and differentiated SH-SY5Y cells challenged with HMC-3-conditioned media under normal and OGD/R conditions. Under OGD/R conditions, differentiated SH-SY5Y cells were less likely to survive exposure to 0.9% NaCl. Expression of caspase-1 and caspase-3 in HMC-3 and differentiated SH-SY5Y cells was altered when exposed to 0.9% NaCl, 0.9% CH3COONa, and their combinations. A total of 0.9% NaCl and 0.9% CH3COONa and their combinations decreased the NO production in HMC-3 cells under normal and OGD/R conditions. Both hypernatremia and hyperchloremia reduced the survival of HMC-3 and differentiated SH-SY5Y cells under OGD/R conditions. Based on the OGD/R in vitro model that mimics human ischemic stroke conditions, it possibly provides a link for the increased death associated with hyperchloremia or hypernatremia in stroke patients.
Project description:Neuronal apoptosis is a major pathological hallmark of the neonatal hypoxic-ischemic brain damage (HIBD); however, the role of miR-7a-2-3p in the regulation of HIBD remains unknown. The purpose of this study was to explore the possible roles of miR-7a-2-3p in brain injury using a hypoxia-ischemia model in rats and oxygen-glucose deprivation (OGD) model in vitro. Firstly, we established the hypoxia-ischemia (HI) model and verified the model using Zea Longa scores and MRI in rats. Next, the changes of miR-7a-2-3p were screened in the ischemic cortex of neonatal rats by qRT-PCR at 12, 48, and 96 h after HIBD. We have found that the expression of miR-7a-2-3p in the HI rats decreased significantly, compared with the sham group (P < 0.01). Then, we established the OGD model in PC12 cells, SH-SY5Y cells and primary cortical neurons in vitro and qRT-PCR was used to confirm the changes of miR-7a-2-3p in these cells after the OGD. In order to determine the function of miR-7a-2-3p, PC12 cells, SH-SY5Y cells and rat primary cortical neurons were randomly divided into normal, OGD, mimic negative control (mimic-NC) and miR-7a-2-3p groups. Then, Tuj1+ (neuronal marker) staining, TUNEL assay (to detect apoptotic cells) and MTT assay (to investigate cell viability) were performed. We have found that the number of PC12 cells, SH-SY5Y cells and cortical neurons in the miR-7a-2-3p groups increased significantly (P < 0.01) in comparison to the OGD groups. The survival of cortical neurons in the miR-7a-2-3p group was improved markedly (P < 0.01), while the apoptosis of neurons in the miR-7a-2-3p group was significantly decreased (P < 0.01), compared with the normal group. Lastly, we investigated the target genes of miR-7a-2-3p by using the prediction databases (miRDB, TargetScan, miRWalk, and miRmap) and verified the target genes with qRT-PCR in the HI rats. Bioinformatics prediction showed that Vimentin (VIM), pleiomorphic adenoma gene 1(PLAG1), dual specificity phosphatase 10 (DUSP10), NAD(P)H dehydrogenase, quinone 1 (NQO1) and tumor necrosis factor receptor superfamily member 1B (TNFRSF1B) might be the targets of miR-7a-2-3p and the qRT-PCR confirmed that VIM increased in the HI rats (P < 0.01). In conclusion, miR-7a-2-3p plays a crucial role in the hypoxic-ischemic injury, and is associated with regulation of VIM.
Project description:As brain-resident immune cells, microglia (MG) survey the brain parenchyma to maintain homeostasis during development and following injury. Research in perinatal stroke, a leading cause of lifelong disability, has implicated MG as targets for therapeutic intervention during stroke. Although MG responses are complex, work in developing rodents suggests that MG limit brain damage after stroke. However, little is known about how energy-limiting conditions affect MG survival and mobility (motility and migration) in developing brain tissues. Here, we used confocal time-lapse imaging to monitor MG viability and mobility during hypoxia or oxygen-glucose deprivation (OGD) in hippocampal tissue slices derived from neonatal GFP-reporter mice (CX3CR1(GFP/+) ). We found that MG remain viable for at least 6 h of hypoxia but begin to die after 2 h of OGD, while both hypoxia and OGD reduce MG motility. Unexpectedly, some MG retain or recover motility during OGD and can engulf dead cells. Additionally, MG from younger neonates (P2-P3) are more resistant to OGD than those from older ones (P6-P7), indicating increasing vulnerability with developmental age. Finally, transient (2 h) OGD also increases MG death, and although motility is rapidly restored after transient OGD, it remains below control levels for many hours. Together, these results show that MG in neonatal mouse brain tissues are vulnerable to both transient and sustained OGD, and many MG die within hours after onset of OGD. Preventing MG death may, therefore, provide a strategy for promoting tissue restoration after stroke.