IcarisideⅡ alleviates oxygen-glucose deprivation and reoxygenation-induced PC12 celloxidative injury by activating Nrf2 / SIRT3signaling pathway

OBJECTIVE To investigate icariside(ICS)Ⅱ protects against PC12 cel damage induced by oxygen-glucose deprivation and reoxygenation and explore its mechanism.METHODS The oxidative stress injury model was induced by oxygen-glucose deprivation/reoxygenation(OGD/R) 2 h/24 h in PC12 cells.N-acetyl-lcysteine(NAC),a classical anti-oxidant,was used as positive control.Pharmacodynamic experimental study groups as follows:control,control+ICS Ⅱ50 μmol·L^(-1),OGD/R,OGD/R+ICSⅡ 12.5 μmol·L^(-1),OGD/R + ICS Ⅱ 25 μmol·L^(-1),OGD/R + ICS Ⅱ50 μmol·L^(-1),and OGD/R+NAC 100 μmol·L^(-1) groups.Cell viability and lactate dehydrogenase(LDH) leakage rate were measured by MTT assay and LDH ELISA kit,respectively.Moreover,reactive oxygen species(ROS) ELISA kit was used for detection of intracellular ROS generation,Mito-SOX fluorescence staining was used for detecting production of ROS in mitochondria and mitochondrial membrane potential(MMP)was detected by rhodamine 123 dye.In addition,PC12 cells apoptosis was detected by one-step TUNEL assay.Furthermore,the expressions of nuclear factor erythroid 2-related factors(Nrf2),Keap1,HO^(-1),NQO^(-1),silent information regulator 3(SIRT3),IDH2,Bax,Bcl-2 and caspase 3 were detected by Western blotting analysis.RESULTS The results of MTT and LDH assay showed that OGD/R reduced the cell viability and improved LDH release compared with the control or ICSⅡ 50 μmol·L^(-1) alone(P<0.01).Meanwhile,OGD/R not only increased intracellular and mitochondrial ROS generation,but also elevated the fluorescence intensity of TUNEL staining,at the same time,the MMP was declined when challenged by OGD/R.Furthermore,the Western blotting results showed that OGD/R induced the increase in the expression of cytoplasm-Nrf2,Keap1,Bax and cleaved-caspase 3 level,while the decrease in the expression of nucleus-Nrf2,HO^(-1),NQO^(-1),SIRT3,IDH2 and Bcl-2(P<0.05).However,ICS Ⅱ significantly increased the viability of PC12 cells and reduced LDH leakage(P<0.01).Notably,ICS Ⅱ also suppressed ROS generation both in the intracellular and mitochondria,as well as restored MMP.It was also worthy to note that ICS Ⅱ decreased the expressions of cytoplasmNrf2,Keap1,Bax and the level of cleaved-caspase3,whereas,it increased the expressions of nucleus-Nrf2,HO^(-1),NQO^(-1),SIRT3,IDH2 and Bcl-2(P<0.05).CONCLUSION ICSⅡ reduced OGD/Rinduced oxidative damage in PC12 cells under the laboratory conditions,and its underlying mechanism may be related to the regulation of Nrf2/SIRT3 signaling pathway.

Neuroprotective effects of neural stem cells pretreated with neuregulin1β on PC12 cells exposed to oxygen-glucose deprivation/reoxygenation

Studies on ischemia/reperfusion(I/R)injury suggest that exogenous neural stem cells(NSCs)are ideal candidates for stem cell therapy reperfusion injury.However,NSCs are difficult to obtain owing to ethical limitations.In addition,the survival,differentiation,and proliferation rates of transplanted exogenous NSCs are low,which limit their clinical application.Our previous study showed that neuregulin1β(NRG1β)alleviated cerebral I/R injury in rats.In this study,we aimed to induce human umbilical cord mesenchymal stem cells into NSCs and investigate the improvement effect and mechanism of NSCs pretreated with 10 nM NRG1βon PC12 cells injured by oxygen-glucose deprivation/reoxygenation(OGD/R).Our results found that 5 and 10 nM NRG1βpromoted the generation and proliferation of NSCs.Co-culture of NSCs and PC12 cells under condition of OGD/R showed that pretreatment of NSCs with NRG1βimproved the level of reactive oxygen species,malondialdehyde,glutathione,superoxide dismutase,nicotinamide adenine dinucleotide phosphate,and nuclear factor erythroid 2-related factor 2(Nrf2)and mitochondrial damage in injured PC12 cells;these indexes are related to ferroptosis.Research has reported that p53 and solute carrier family 7 member 11(SLC7A11)play vital roles in ferroptosis caused by cerebral I/R injury.Our data show that the expression of p53 was increased and the level of glutathione peroxidase 4(GPX4)was decreased after RNA interference-mediated knockdown of SLC7A11 in PC12 cells,but this change was alleviated after co-culturing NSCs with damaged PC12 cells.These findings suggest that NSCs pretreated with NRG1βexhibited neuroprotective effects on PC12 cells subjected to OGD/R through influencing the level of ferroptosis regulated by p53/SLC7A11/GPX4 pathway.

Protective effect of icarisideⅡ on oxygen-glucose deprivation and reoxygenation-induced injury incerebral cortical neurons

OBJECTIVE To explore the effect of icariside Ⅱ(ICS Ⅱ) on oxygen-glucose deprivation and reoxygenation(OGD/R)-induced injury in cerebral cortical neuronal cels.METHODS Primary cerebral cortical neuronal cells were deprived of oxygen and glucose for 2 h to simulate ischemic stroke injury in vitro.The experiment was divided into 8 groups,which were control,control+ICSⅡ 25 μmol·L^(-1),OGD/R,OGD/R+ICSⅡ(6.25,12.5,25 μmol·L^(-1)),OGD/R+3-methyladenine(3-MA) and OGD/R+Rapamycin(Rap).The protective effect of ICS Ⅱ were detected by MTT assay and lactate dehydrogenase(LDH),respectively.Autophagic flux and autophagy related proteins expressions were detected by using adenovirus harboring tf-LC3 and Western blotting,respectively.RESULTS Compared with OGD/R group,the cell viability treated with ICSⅡwas elevated in a concentration-dependent manner,and the leakage rate of LDH was lowed.Moreover,ICSⅡ not only suppressed OGD/R-induced autophagic flux,but also inhibited the increase of LC3-Ⅱ/LC3-Ⅰ ratio and Beclin 1 after OGD/R insulted.CONCLUSION ICS Ⅱ exerts protective effects on OGD/R-induced cerebral cortical neuronal cells through inhibiting excessive autophagy.

Protective effect of ginsenoside Rg1 on 661W cells exposed to oxygen-glucose deprivation/reperfusion via keap1/nrf2 pathway

AIM:To construct an in vitro model of oxygen-glucose deprivation/reperfusion(OGD/R)induced injury to the optic nerve and to study the oxidative damage mechanism of ischemia-reperfusion(I/R)injury in 661W cells and the protective effect of ginsenoside Rg1.METHODS:The 661W cells were treated with different concentrations of Na2S2O4 to establish OGD/R model in vitro.Apoptosis,intracellular reactive oxygen species(ROS)levels and superoxide dismutase(SOD)levels were measured at different time points during the reperfusion injury process.The injury model was pretreated with graded concentrations of ginsenoside Rg1.Real-time polymerase chain reaction(PCR)was used to measure the expression levels of cytochrome C(cyt C)/B-cell lymphoma-2(Bcl2)/Bcl2 associated protein X(Bax),heme oxygenase-1(HO-1),caspase9,nuclear factor erythroid 2-related factor 2(nrf2),kelch-like ECH-associated protein 1(keap1)and other genes.Western blot was used to detect the expression of nrf2,phosphorylated nrf2(pnrf2)and keap1 protein levels.RESULTS:Compared to the untreated group,the cell activity of 661W cells treated with Na2S2O4 for 6 and 8h decreased(P<0.01).Additionally,the ROS content increased and SOD levels decreased significantly(P<0.01).In contrast,treatment with ginsenoside Rg1 reversed the cell viability and SOD levels in comparison to the Na_(2)S_(2)O_(4)treated group(P<0.01).Moreover,Rg1 reduced the levels of caspase3,caspase9,and cyt C,while increasing the Bcl2/Bax level.These differences were all statistically significant(P<0.05).Western blot analysis showed no significant difference in the protein expression levels of keap1 and nrf2 with Rg1 treatment,however,Rg1 significantly increased the ratio of pnrf2/nrf2 protein expression compared to the Na_(2)S_(2)O_(4)treated group(P<0.001).CONCLUSION:The OGD/R process is induced in 661W cells using Na_(2)S_(2)O_(4).Rg1 inhibits OGD/R-induced oxidative damage and alleviates the extent of apoptosis in 661W cells through the keap1/nrf2 pathway.These results suggest a potential protective effect of Rg1 against retinal I/R injury.

Low-Dose Ethanol Preconditioning Protects Against Oxygen-Glucose Deprivation/Reoxygenation-Induced Neuronal Injury By Activating Large Conductance,Ca2+-Activated K+Channels In Vitro

Increasing evidence suggests that low to mod- erate ethanol ingestion protects against the deleterious effects of subsequent ischemia/reperfusion; however, the underlying mechanism has not been elucidated. In the present study, we showed that expression of the neuronal large-conductance, Ca2＋-activated K＋ channel （BKca） α- subunit was upregulated in cultured neurons exposed to oxygen-glucose deprivation/reoxygenation （OGD/R） compared with controls. Preconditioning with low-dose ethanol （10 mmol/L） increased cell survival rate in neurons subjected to OGD/R, attenuated the OGD/R-induced elevation of cytosolic Ca2＋ levels, and reduced the number of apoptotic neurons. Western blots revealed that ethanol preconditioning upregulated expression of the anti-apoptotic protein Bcl-2 and downregulated the pro-apoptotic protein Bax. The protective effect of ethanol precondi- tioning was antagonized by a BKα channel inhibitor, paxilline. Inside-out patches in primary neurons also demonstrated the direct activation of the BKCa channel by 10 mmol/L ethanol. The above results indicated that low- dose ethanol preconditioning exerts its neuroprotective effects by attenuating the elevation of cytosolic Ca2＋ and preventing neuronal apoptosis, and this is mediated by BKca channel activation.

Tilianin extracted from Xiangqinglan(Herba Dracocephali Moldovicae)inhibits apoptosis induced by mitochondrial pathway and endoplasmic reticulum stress in H9c2 cells after oxygen-glucose deprivation/reoxygenation

OBJECTIVE:To investigate the efficacy of tilianin extracted from Xiangqinglan(Herba Dracocephali Moldovicae)on apoptosis of H9c2 cell after oxygenglucose deprivation/reoxygenation(OGD/R)and the mechanism.METHODS:Tilianin was obtained from Beijing Inluck Science and Technology Development Co.Ltd.,with purity≥98%.The OGD/R model was established in H9c2 cells.Flow cytometry detected the mitochondrial membrane potential,apoptosis rates,mitochondrial reactive oxygen species(ROS)and calcium ion concentration.Succinate dehydrogenase(SDH)activity,succinate content and levels of tumor necrosis factor-α(TNF-α),interleukin-6(IL-6)and interleukin-1β(IL-1β)were detected with enzyme-linked immunosorbent assay.Western blot measured protein levels.RESULTS:Tilianin significantly reduced the apoptotic rates,ROS levels,calcium ion concentration,succinate content,and,levels of TNF-α,IL-6 and IL-1βof OGD/R cells,while significantly increased the membrane potential and SDH activity in mitochondria.Western blot analysis showed that tilianin significantly up-regulated pCalmodulin-dependent protein kinaseⅡand voltagedependent anion selective channel levels in OGD/R cells,while significantly down-regulated p-protein kinase B,Bcl-2-associated X,and dynamin-related protein 1 levels related to apoptosis in the mitochondrial pathway.Moreover,tilianin significantly up-regulated B-cell lymphoma-2 and mitochondrial protein 2 related to the inhibition of apoptosis.Furthermore,tilianin downregulated phosphorylated-apoptosis signal-regulated kinase 1,phosphorylated-p38 and C/EBP homologous protein related to endoplasmic reticulum stress.CONCLUSIONS:Tilianin may inhibit OGD/R-induced H9c2 cell apoptosis mediated by mitochondrial pathway and endoplasmic reticulum stress,thus protecting cardiomyocytes.

Activated Drp1 regulates p62-mediated autophagic flux and aggravates inflammation in cerebral ischemia-reperfusion via the ROS-RIP1/RIP3-exosome axis

Background: Cerebral ischemia-reperfusion injury(CIRI) refers to a secondary brain injury that can occur when the blood supply to the ischemic brain tissue is restored. However, the mechanism underlying such injury remains elusive.Methods: The 150 male C57 mice underwent middle cerebral artery occlusion(MCAO) for 1 h and reperfusion for 24 h,Among them, 50 MCAO mice were further treated with Mitochondrial division inhibitor 1(Mdivi-1) and 50 MCAO mice were further treated with N-acetylcysteine(NAC). SH-SY5Y cells were cultured in a low-glucose culture medium for 4 h under hypoxic conditions and then transferred to normal conditions for 12 h. Then, cerebral blood flow, mitochondrial structure, mitochondrial DNA(mtDNA) copy number, intracellular and mitochondrial reactive oxygen species(ROS),autophagic flux, aggresome and exosome expression profiles, cardiac tissue structure, mitochondrial length and cristae density, mtDNA and ROS content, as well as the expression of Drp1-Ser616/Drp1, RIP1/RIP3, LC3 II/I, TNF-α,IL-1β, etc., were detected under normal or Drp1 interference conditions.Results: The mtDNA content, ROS levels, and Drp1-Ser616/Drp1 were elevated by 2.2, 1.7 and 2.7 times after CIRI(P<0.05). However, the high cytoplasmic LC3 II/I ratio and increased aggregation of p62 could be reversed by 44%and 88% by Drp1 short hairpin RNA(shRNA)(P<0.05). The low fluorescence intensity of autophagic flux and the increased phosphorylation of RIP3 induced by CIRI could be attenuated by ROS scavenger, NAC(P<0.05). RIP1/RIP3inhibitor Necrostatin-1(Nec-1) restored 75% to a low LC3 II/I ratio and enhanced 2 times to a high RFP-LC3 after Drp1 activation(P<0.05). In addition, although CIRI-induced ROS production caused no considerable accumulation of autophagosomes(P>0.05), it increased the packaging and extracellular secretion of exosomes containing p62 by 4–5 times, which could be decreased by Mdivi-1, Drp1 shRNA, and Nec-1(P<0.05). Furthermore, TNF-α and IL-1βincreased in CIRI-derived exosomes could increase RIP3 phosphorylation in normal or oxygen–glucose deprivation/reoxygenation(OGD/R) conditions(P<0.05).Conclusions: CIRI activated Drp1 and accelerated the p62-mediated formation of autophagosomes while inhibiting the transition of autophagosomes to autolysosomes via the RIP1/RIP3 pathway activation. Undegraded autophagosomes were secreted extracellularly in the form of exosomes, leading to inflammatory cascades that further damaged mitochondria, resulting in excessive ROS generation and the blockage of autophagosome degradation,triggering a vicious cycle.

LncRNA SNHG12 ameliorates brain microvascular endothelial cell injury by targeting miR-199a

Long non-coding RNAs regulate brain microvascular endothelial cell death, the inflammatory response and angiogenesis during and after ischemia/reperfusion and oxygen-glucose deprivation/reoxygenation（OGD/R） insults. The long non-coding RNA, SNHG12, is upregulated after ischemia/reperfusion and OGD/R in microvascular endothelial cells of the mouse brain. However, its role in ischemic stroke has not been studied. We hypothesized that SNHG12 positively regulates ischemic stroke, and therefore we investigated its mechanism of action. We established an OGD/R mouse cell model to mimic ischemic stroke by exposing brain microvascular endothelial cells to OGD for 0, 2, 4, 8, 16 or 24 hours and reoxygenation for 4 hours. Quantitative real-time polymerase chain reaction showed that SNHG12 levels in brain microvascular endothelial cells increased with respect to OGD exposure time. Brain microvascular endothelial cells were transfected with pc DNA-control, pc DNA-SNHG12, si-control, or si-SNHG12. After exposure to OGD for 16 hours, these cells were then analyzed by 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl-2-H-tetrazolium bromide, trypan blue exclusion, western blot, and capillary-like tube formation assays. Overexpression of SNHG12 inhibited brain microvascular endothelial cell death and the inflammatory response but promoted angiogenesis after OGD/R, while SNHG12 knockdown had the opposite effects. miR-199a was identified as a target of SNHG12, and SNHG12 overexpression reversed the effect of miR-199a on brain microvascular endothelial cell death, the inflammatory response, and angiogenesis. These findings suggest that SNHG12 suppresses endothelial cell injury induced by OGD/R by targeting miR-199a.

Vav1 promotes inflammation and neuronal apoptosis in cerebral ischemia/reperfusion injury by upregulating microglial and NLRP3 inflammasome activation

Microglia,which are the resident macrophages of the central nervous system,are an important part of the inflammatory response that occurs after cerebral ischemia.Vav guanine nucleotide exchange factor 1(Vav1) is a guanine nucleotide exchange factor that is related to microglial activation.However,how Vav1 participates in the inflammato ry response after cerebral ischemia/reperfusion inj ury remains unclea r.In this study,we subjected rats to occlusion and repe rfusion of the middle cerebral artery and subjected the BV-2 mic roglia cell line to oxygen-glucose deprivatio n/reoxygenation to mimic cerebral ischemia/repe rfusion in vivo and in vitro,respectively.We found that Vav1 levels were increased in the brain tissue of rats subjected to occlusion and reperfusion of the middle cerebral arte ry and in BV-2 cells subjected to oxygen-glucose deprivation/reoxygenation.Silencing Vav1 reduced the cerebral infarct volume and brain water content,inhibited neuronal loss and apoptosis in the ischemic penumbra,and im p roved neurological function in rats subjected to occlusion and repe rfusion of the middle cerebral artery.Further analysis showed that Vav1 was almost exclusively localized to microglia and that Vav1 downregulation inhibited microglial activation and the NOD-like receptor pyrin 3(NLRP3) inflammasome in the ischemic penumbra,as well as the expression of inflammato ry facto rs.In addition,Vov1 knoc kdown decreased the inflammatory response exhibited by BV-2 cells after oxygen-glucose deprivation/reoxyge nation.Taken together,these findings show that silencing Vav1 attenuates inflammation and neuronal apoptosis in rats subjected to cerebral ischemia/repe rfusion through inhibiting the activation of mic roglia and NLRP3 inflammasome.

Silencing miRNA-324-3p protects against cerebral ischemic injury via regulation of the GATA2/A1R axis

Previous studies have suggested that miR-324-3p is related to the pathophysiology of cerebral ischemia,but the mechanism underlying this relationship is unclea r.In this study,we found that miR-324-3p expression was decreased in patients with acute ischemic stroke and in in vitro and in vivo models of ischemic stro ke.miR-324-3p agomir potentiated ischemic brain damage in rats subjected to middle cerebral artery occlusion,as indicated by increased infarct volumes and cell apoptosis rates and greater neurological deficits.In a PC12 cell oxygen-glucose deprivation/reoxygenation model,a miR-324-3 p mimic decreased cell viability and expression of the anti-apoptotic protein BCL2 and increased expression of the pro-apoptotic protein BAX and rates of cell apoptosis,whereas treatment with a miR-324-3p inhibitor had the opposite effects.Silencing miR-324-3p increased adenosine A1 receptor(A1R)expression thro ugh regulation of GATA binding protein 2(GATA2).These findings suggest that silencing miR-324-3p reduces ischemic brain damage via the GATA2/A1R axis.

Upregulation of CDGSH iron sulfur domain 2 attenuates cerebral ischemia/reperfusion injury

CDGSH iron sulfur domain 2 can inhibit ferroptosis,which has been associated with cerebral ischemia/reperfusion,in individuals with head and neck cancer.Therefore,CDGSH iron sulfur domain 2 may be implicated in cerebral ischemia/reperfusion injury.To validate this hypothesis in the present study,we established mouse models of occlusion of the middle cerebral artery and HT22 cell models of oxygen-glucose deprivation and reoxygenation to mimic cerebral ischemia/reperfusion injury in vivo and in vitro,respectively.We found remarkably decreased CDGSH iron sulfur domain 2 expression in the mouse brain tissue and HT22 cells.When we used adeno-associated virus and plasmid to up-regulate CDGSH iron sulfur domain 2 expression in the brain tissue and HT22 cell models separately,mouse neurological dysfunction was greatly improved;the cerebral infarct volume was reduced;the survival rate of HT22 cells was increased;HT22 cell injury was alleviated;the expression of ferroptosis-related glutathione peroxidase 4,cystine-glutamate antiporter,and glutathione was increased;the levels of malondialdehyde,iron ions,and the expression of transferrin receptor 1 were decreased;and the expression of nuclear-factor E2-related factor 2/heme oxygenase 1 was increased.Inhibition of CDGSH iron sulfur domain 2 upregulation via the nuclear-factor E2-related factor 2 inhibitor ML385 in oxygen-glucose deprived and reoxygenated HT22 cells blocked the neuroprotective effects of CDGSH iron sulfur domain 2 up-regulation and the activation of the nuclear-factor E2-related factor 2/heme oxygenase 1 pathway.Our data indicate that the up-regulation of CDGSH iron sulfur domain 2 can attenuate cerebral ischemia/reperfusion injury,thus providing theoretical support from the perspectives of cytology and experimental zoology for the use of this protein as a therapeutic target in patients with cerebral ischemia/reperfusion injury.

CircCDC14A沉默保护星形胶质细胞免受OGD/R诱导的损伤作用机制分析

目的探讨CirCDC14A沉默通过调节miR-153-3p/JAK1轴保护星形胶质细胞免受氧糖剥夺/复糖复氧(OGD/R)诱导的损伤机制。方法体外培养新生大鼠脑皮质星形胶质细胞,采用CCK-8法法检测各组细胞活力;采用Annexin V-FITC/PI染色检测细胞凋亡情况;采用Western blot法检测各组p53、Bax、Bcl-2蛋白表达水平,并采用双荧光素酶报告基因实验分析CirCDC14A与miR-153-3p、miR-153-3p与JAK1的关系。结果随着时间的延长,细胞活性呈上升趋势;pcDNA3.0 CirCDC14A+si JAK1组48 h及72 h细胞活力低于si-NC组、OGD/R组、OGD/R+Si+Con mimcs组(P<0.05);与si-NC组相比,OGD/R组、OGD/R+Si+Con mimcs组、pcDNA3.0-CirCDC14A+si JAK1+miR-153-3p mimcs组细胞凋亡明显增加,且pcDNA3.0-CirCDC14A+si JAK1+miR-153-3p mimcs组细胞凋亡高于GD/R+Si+Con mimcs组(P<0.05);Western blot结果表明:pcDNA3.0-CirCDC14A+si JAK1+miR-153-3p mimcs组p53、Bax、Bcl-2蛋白表达水平低于OGD/R组、OGD/R+Si+Con mimcs组和si-NC组(P<0.05);miR-153-3p mimic能降低CirCDC14A WT、JAK1-WT的荧光素酶活性(P<0.05);pcDNA3.0-CirCDC14A+si JAK1+miR-153-3p mimcs组miR-153-3p水平低于于其余3组(P<0.05),JAK1蛋白水平高于其余3组(P<0.05)。结论CirCDC14A基因沉默可能通过调控miR-153-3p/JAK1轴抑制OGD/R诱导的大鼠星形胶质细胞凋亡,引起细胞活力及p53、Bax、Bcl-2蛋白表达水平降低。

Apoptosis inhibitory effect of anti-miR-146b on hippocampal neurons of OGD/R-induced injury

Objective:To construct a cellular model of oxygen-glucose deprivation and reoxygenation (OGD/R)-induced injury in hippocampal neuronsin vitro, and to explore the inhibitory effect of anti-miR-146b on the apoptosis of hippocampal neurons of ischemic/reperfusion injury. Methods: Primary rat hippocampal neurons were cultured, and oxygen-glucose deprivation and reoxygenation (OGD/R) were constructed. The anti-miR-146b lentivirus was used to transfect the hippocampal neurons, and the cells were divided into the normal group, the OGD/R group and the OGD/R + anti-miR-146b group. Real time fluorescence quantitative PCR (qRT-PCR) was used to detect the mRNA expression of miR-146b, KLF7, Caspase-3, Bcl-2 and Bax in each group. Cell viability was detected by CCK8 assay, and apoptosis was detected by Hoechst33342/PI double staining.Results: Compared with the normal group, the cell morphology of the OGD/R group and the OGD/R + anti-miR-146b group was damaged, the cell activity was decreased, and the cell apoptosis rate was increased significantly (P<0.05). However, Compared with OGD/R group, the cell morphology of the OGD/R + KLF7 group was improved, the cell activity was increased, and the apoptosis rate was decreased significantly (P<0.05). Compared with the normal group, the mRNA expression levels of miR-146b, KLF7, Caspase-3, Bax and Bcl-2 in the OGD/R group and the OGD/R + KLF7 group was increased (P<0.05). Compared with the OGD/R group, the mRNA expression of KLF7, Bcl-2 were increased in the OGD/R + KLF7 group significantly, however, the mRNA expression of miR-146b, Caspase-3, Bax were decreased significantly (P<0.05).Conclusion:Anti-miR-146b play protective effect on hippocampal neurons of OGD/R-induced injury. The mechanism may be related to upregulation of KLF7 signaling pathway, downregulation expression of Caspase-3 and Bax, upregulation expression of Bcl-2, and inhibition of apoptosis induced by OGD/R.

Total Saponins of Panax notoginseng Activate Akt/mTOR Pathway and Exhibit Neuroprotection in vitro and in vivo against Ischemic Damage

Objective:To reveal the neuroprotective effect and the underlying mechanisms of a mixture of the main components of Panax notoginseng saponins(TSPN)on cerebral ischemia-reperfusion injury and oxygenglucose deprivation/reoxygenation(OGD/R)of cultured cortical neurons.Methods:The neuroprotective effect of TSPN was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)assay,flow cytometry and live/dead cell assays.The morphology of dendrites was detected by immunofluorescence.Middle cerebral artery occlusion(MCAO)was developed in rats as a model of cerebral ischemia-reperfusion.The neuroprotective effect of TSPN was evaluated by neurological scoring,tail suspension test,2,3,5-triphenyltetrazolium chloride(TTC)and Nissl stainings.Western blot analysis,immunohistochemistry and immunofluorescence were used to measure the changes in the Akt/mammalian target of rapamycin(mTOR)signaling pathway.Results:MTT showed that TSPN(50,25 and 12.5μg/m L)protected cortical neurons after OGD/R treatment(P<0.01 or P<0.05).Flow cytometry and live/dead cell assays indicated that 25μg/m L TSPN decreased neuronal apoptosis(P<0.05),and immunofluorescence showed that 25μg/m L TSPN restored the dendritic morphology of damaged neurons(P<0.05).Moreover,12.5μg/m L TSPN downregulated the expression of Beclin-1,Cleaved-caspase 3 and LC3 B-Ⅱ/LC3 B-Ⅰ,and upregulated the levels of phosphorylated(p)-Akt and p-mTOR(P<0.01 or P<0.05).In the MCAO model,50μg/m L TSPN improved defective neurological behavior and reduced infarct volume(P<0.05).Moreover,the expression of Beclin-1 and LC3 B in cerebral ischemic penumbra was downregulated after 50μg/m L TSPN treatment,whereas the p-mTOR level was upregulated(P<0.05 or P<0.01).Conclusions:TSPN promoted neuronal survival and protected dendrite integrity after OGD/R and had a potential therapeutic effect by alleviating neurological deficits and reversing neuronal loss.TSPN promoted p-mTOR and inhibited Beclin-1 to alleviate ischemic damage,which may be the mechanism that underlies the neuroprotective activity of TSPN.