Delavatine A Attenuates OGD/R-Caused PC12 Cell Injury and Apoptosis through Suppressing the MKK7/JNK Signaling Pathway.

Delavatine A (DA) is an unusual isoquinoline alkaloid with a novel skeleton isolated from Chinese folk medicine Incarvillea delavayi. Studies conducted in our lab have demonstrated that DA has potential anti-inflammatory activity in lipopolysaccharide (LPS)-treated BV-2 cells. DA, however, has not been studied for its protective effect on neuronal cells yet. Thus, to explore whether DA can protect neurons, oxygen and glucose deprivation/reperfusion (OGD/R)-injured PC12 cell and middle cerebral artery occlusion/reperfusion (MCAO/R) rat model were used to assess the protective efficacy of DA against OGD/R damaged PC12 cells and MCAO/R injured rats. Our results demonstrated that DA pretreatment (0.31-2.5 µM) dose-dependently increased cell survival and mitochondrial membrane potential (MMP), whereas it lowered the leakage of lactate dehydrogenase (LDH), intracellular cumulation of Ca2+, and overproduction of reactive oxygen species (ROS), and inhibited the apoptosis rate in OGD/R-injured PC12 cells. Western blot demonstrated that DA pretreatment lowered the expression of apoptotic proteins and repressed the activation of the mitogen-activated protein kinase kinase 7 (MKK7)/c-Jun N-terminal kinase (JNK) pathway. It was also found that the neuroprotective efficacy of DA was significantly reversed by co-treatment with the JNK agonist anisomycin, suggesting that DA reduced PC12 cell injury and apoptosis by suppressing the MKK7/JNK pathway. Furthermore, DA oral administration greatly alleviated the neurological dysfunction and reduced the infarct volume of MCAO/R rats. Taken together, DA could ameliorate OGD/R-caused PC12 cell injury and improve brain ischemia/reperfusion (I/R) damage in MCAO/R rats, and its neuroprotection might be attributed to suppressing the MKK7/JNK signaling pathway.

[Mitophagy mediated by ligustilide relieves OGD/R-induced injury in HT22 cells].

Mitochondrion, as the main energy-supply organelle, is the key target region that determines neuronal survival and death during ischemia. When an ischemic stroke occurs, timely removal of damaged mitochondria is very important for improving mitochondrial function and repairing nerve damage. This study investigated the effect of ligustilide(LIG), an active ingredient of Chinese medicine, on mitochondrial function and mitophagy based on the oxygen and glucose deprivation/reperfusion(OGD/R)-induced injury model in HT22 cells. By OGD/R-induced injury model was induced in vitro, HT22 cells were pre-treated with LIG for 3 h, and the cell viability was detected by the CCK-8 assay. Immunofluorescence and flow cytometry were used to detect indicators related to mitochondrial function, such as mitochondrial membrane potential, calcium overload, and reactive oxygen species(ROS). Western blot was used to detect the expression of dynamin-related protein 1(Drp1, mitochondrial fission protein) and cleaved caspase-3(apoptotic protein). Immunofluorescence was used to observe the co-localization of the translocase of outer mitochondrial membrane 20(TOMM20, mitochondrial marker) and lysosome-associated membrane protein 2(LAMP2, autophagy marker). The results showed that LIG increased the cell viability of HT22 cells as compared with the conditions in the model group. Furthermore, LIG also inhibited the ROS release, calcium overload, and the decrease in mitochondrial membrane potential in HT22 cells after OGD/R-induced injury, facilitated Drp1 expression, and promoted the co-localization of TOMM20 and LAMP2. The findings indicate that LIG can improve the mitochondrial function after OGD/R-induced injury and promote mitophagy. When mitophagy inhibitor mdivi-1 was administered, the expression of apoptotic protein increased, suggesting that the neuroprotective effect of LIG may be related to the promotion of mitophagy.

MiR-92b-3p regulates oxygen and glucose deprivation-reperfusion-mediated apoptosis and inflammation by targeting TRAF3 in PC12 cells.

NEW FINDINGS: What is the central question of this study? MiR-92b-3p was found to be reduced in a rat model of middle cerebral artery occlusion: what are the functions of miR-92b-3p in oxygen and glucose deprivation-reperfusion (OGD/R)? What is the main finding and its importance? MiR-92b-3p abated apoptosis, mitochondrial dysfunction and inflammation caused by OGD/R via targeting TRAF3, suggesting that miR-92b-3p may serve as a potential therapeutic target in ischaemic stroke treatment. ABSTRACT: Stroke is the most common cause of human neurological disability. MiR-92b-3p has been shown to be decreased in a rat model of middle cerebral artery occlusion, but its effects in cerebral ischaemic insult are unknown. In this study, PC12 cells were exposed to oxygen and glucose deprivation-reperfusion (OGD/R) to establish cerebral ischaemic injury in vitro. Quantitative real time-PCR analysis demonstrated that OGD/R exposure led to down-regulation of miR-92b-3p and increased mRNA and protein levels of tumour necrosis factor receptor-associated factor 3 (TRAF3). Gain of miR-92b-3p expression facilitated cell survival; attenuated lactate dehydrogenase leakage, cell apoptosis, caspase 3 activity and cleaved-caspase 3 (c-caspase 3) expression; and decreased the Bax/Bcl-2 ratio. Furthermore, miR-92b-3p repressed mitochondrial membrane potential depolarization, reactive oxygen species production, cytochrome c protein expression, inflammatory cytokine production and the reduction of ATP content. MiR-92b-3p directly targeted the 3'-untranslated region of TRAF3 and decreased TRAF3 expression. Reinforced expression of TRAF3 partly abrogated the biological activity of miR-92b-3p during OGD/R. Hence, miR-92b-3p abated apoptosis, mitochondrial dysfunction and inflammatory responses induced by OGD/R by targeting TRAF3.

[Effect of ligustilide on oxygen and glucose deprivation/reperfusion-induced mitochondria fission in PC12 cells].

This study aimed to investigate the effect and mechanism of ligustilide, the main active ingredient in Ligusticum wallichii, on mitochondria fission after PC12 cell injury induced by oxygen and glucose deprivation/reperfusion(OGD/R). In the experiment, an OGD/R model was established in vitro, and PC12 cells were pre-treated with ligustilide for 3 h, and then the cell viability was detected by CCK-8 method. The effect of different concentrations of ligustilide on the morphology of PC12 cells after OGD/R injury was observed under an inverted microscope. Transmission electron microscopy was used to observe the mitochondrial fission of PC12 cells after OGD/R injury. DCFH-DA immunofluorescence staining method was used to detect intracellular reactive oxygen species(ROS) changes. Changes in mitochondria membrane potential(MMP) were detected by flow cytometry. Hochest 33258 was used to observe the apoptosis of PC12 cells. Western blot was used to detect changes in cytochrome C(Cyt C) content in mitochondria and cytoplasm, and mitochondrial fission-related proteins Drp 1 and Fis 1. All results showed that compared with the model group, ligustilide significantly increased the survival rate of PC12 cells and the number of cells. Further experiments showed that ligustilide inhibited the release of ROS and decline of mitochondrial membrane potential in PC12 cells after OGD/R injury. Moreover, ligustilide reduced the release of Cyt C and promoted the expressions of Drp1 and Fis1 in mitochondrial fission proteins. Verification experiments showed that mitochondrial fission inhibitor mdivi-1 decreased cell survival rate and inhibited fission. The results indicated that ligustilide exerted neuro-protective effects by promoting mitochondrial fission and reducing cell damage. It preliminary proves that the mechanism of ligustilide on ischemic brain injury may be related to the promotion of mitochondrial fission and the maintenance of cell homeostasis.

Naringenin prevents ischaemic stroke damage via anti-apoptotic and anti-oxidant effects.

Apoptosis and oxidative stress are considered to be the major factors associated with the development and progression of many ischaemic cerebrovascular diseases. Naringenin (NAR) is an abundant flavanone in citrus plants and has been found to exhibit anti-oxidant, anti-carcinogenic and anti-apoptotic effects. This study aimed to investigate the anti-apoptotic and anti-oxidant effects of naringenin on ischaemic stroke. In vitro, cortical neuron cells isolated from the brains of neonatal Sprague-Dawley rats were randomly divided into control, oxygen and glucose deprivation/reperfusion (OGD/Rep), NAR-L, NAR-M and NAR-H groups. MTT and RT-PCR were used for cell proliferation and apoptosis-related proteins analyses. The effects of NAR on the Nrf2 signalling pathway were investigated using transfection approaches. Differences in mitochondrial dysfunction were analyzed by flow cytometry. In vivo, middle cerebral artery occlusion (MCAO) model was prepared and neurological defects and the brain wet/dry (W/D) ratio were assessed and recorded; apoptosis was measured based on the TUNEL assay. Additionally, biochemical indices were detected both in vitro and in vivo. NAR promoted cortical neuron cell proliferation, inhibited apoptosis and oxidative stress, and regulated the localization of Nrf2 protein (P<.05). Furthermore, silencing and overexpression of Nrf2 affected cortical neuron cell proliferation and apoptosis (P<.05). In vivo, NAR could alleviate cerebral oedema, improve neurological defects, and reduce apoptosis and oxidative stress (P<.05). These findings demonstrated that NAR could reduce apoptosis and oxidative stress and that Nrf2 signalling pathway is involved in this regulatory process. NAR has health-promoting properties because of its anti-apoptotic and anti-oxidant effects in cases of ischaemic stroke.

Neferine inhibits BMECs pyroptosis and maintains blood-brain barrier integrity in ischemic stroke by triggering a cascade reaction of PGC-1α.

Blood-brain barrier disruption is a critical pathological event in the progression of ischemic stroke (IS). Most studies regarding the therapeutic potential of neferine (Nef) on IS have focused on neuroprotective effect. However, whether Nef attenuates BBB disruption during IS is unclear. We here used mice underwent transient middle cerebral artery occlusion (tMCAO) in vivo and bEnd.3 cells exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) injury in vitro to simulate cerebral ischemia. We showed that Nef reduced neurobehavioral dysfunction and protected brain microvascular endothelial cells and BBB integrity. Molecular docking, short interfering (Si) RNA and plasmid transfection results showed us that PGC-1α was the most binding affinity of biological activity protein for Nef. And verification experiments were showed that Nef upregulated PGC-1α expression to reduce mitochondrial oxidative stress and promote TJ proteins expression, further improves the integrity of BBB in mice. Intriguingly, our study showed that neferine is a natural PGC-1α activator and illustrated the mechanism of specific binding site. Furthermore, we have demonstrated Nef reduced mitochondria oxidative damage and ameliorates endothelial inflammation by inhibiting pyroptosis to improve BBB permeability through triggering a cascade reaction of PGC-1α via regulation of PGC-1α/NLRP3/GSDMD signaling pathway to maintain the integrity of BBB in ischemia/reperfusion injury.

Stigmasterol protects human brain microvessel endothelial cells against ischemia-reperfusion injury through suppressing EPHA2 phosphorylation.

Stigmasterol is a plant sterol with anti-apoptotic, anti-oxidative and anti-inflammatory effect through multiple mechanisms. In this study, we further assessed whether it exerts protective effect on human brain microvessel endothelial cells (HBMECs) against ischemia-reperfusion injury and explored the underlying mechanisms. HBMECs were used to establish an in vitro oxygen and glucose deprivation/reperfusion (OGD/R) model, while a middle cerebral artery occlusion (MCAO) model of rats were constructed. The interaction between stigmasterol and EPHA2 was detected by surface plasmon resonance (SPR) and cellular thermal shift assay (CETSA). The results showed that 10 µmol·L-1 stigmasterol significantly protected cell viability, alleviated the loss of tight junction proteins and attenuated the blood-brain barrier (BBB) damage induced by OGD/R in thein vitro model. Subsequent molecular docking showed that stigmasterol might interact with EPHA2 at multiple sites, including T692, a critical gatekeep residue of this receptor. Exogenous ephrin-A1 (an EPHA2 ligand) exacerbated OGD/R-induced EPHA2 phosphorylation at S897, facilitated ZO-1/claudin-5 loss, and promoted BBB leakage in vitro, which were significantly attenuated after stigmasterol treatment. The rat MCAO model confirmed these protective effects in vivo. In summary, these findings suggest that stigmasterol protects HBMECs against ischemia-reperfusion injury by maintaining cell viability, reducing the loss of tight junction proteins, and attenuating the BBB damage. These protective effects are at least meditated by its interaction with EPHA2 and inhibitory effect on EPHA2 phosphorylation.

7,8-Dihydroxyflavone protects neurons against oxygen-glucose deprivation induced apoptosis and activates the TrkB/Akt pathway.

BACKGROUND: 7,8-dihydroxyflavone (7,8-DHF), a selective agonist of tropomyosin related kinase receptor B (TrkB), is known to exert protective effects in neurodegenerative diseases. However, the role of 7,8-DHF in TrkB signaling after ischemic stroke has remained elusive. METHODS: In the vitro model of ischemic stroke, we investigated the neuroprotective effect of 7,8-DHF through activation of TrkB signaling. Neurons subjected to oxygen and glucose deprivation/reperfusion were treated with the protein kinase inhibitor K252a and a knockdown of TrkB. Cell counting kit-8 (CCK-8) assay, Flow Cytometric Analysis (FACS), TdT-mediated dUTP nick end labeling (TUNEL) assay were conducted for measuring cell viability and numbers of apoptotic cells. And apoptosis-associated proteins were analyzed by Western blotting. RESULTS: Compared with the Control group, OGD/R group revealed lower cell viability by CCK-8 assay FACS and TUNEL assay showed increased rates of neuronal apoptosis. However, 7,8-DHF treatment increased cell viability and reduced neuronal apoptosis. Western blotting indicated upregulated Bax and cleaved caspase-3 and but downregulated Bcl-2 following OGD/R. Whereas 7,8-DHF treatment downregulated Bax and cleaved caspase-3 but upregulated Bcl-2. These changes were accompanied by a significant increase in the phosphorylation of TrkB and Akt following 7,8-DHF administration. However, the administration of K252a and knockdown of TrkB could alleviate those effects. CONCLUSION: Our study demonstrates that activation of TrkB signaling by 7,8-DHF protects neurons against OGD/R injury via the TrkB/Akt pathway, which provides the evidence for the role of TrkB signaling in OGD-induced neuronal damage and may become a potential therapeutic target for ischemic stroke.

miR­363­3p attenuates the oxygen­glucose deprivation/reoxygenation­induced neuronal injury in vitro by targeting PDCD6IP.

The purpose of the present study was to explore the functional role of microRNA (miR)­363­3p and related regulatory mechanisms in cerebral ischemia/reperfusion (I/R) injury. The neuronal cell line SH­SY5Y was exposed to 4 h of oxygen and glucose deprivation (OGD), followed by 6, 12, 24 and 48 h of re­oxygenation to mimic I/R injury in vitro. Cell viability, apoptosis and inflammation were assessed by CCK­8, lactate dehydrogenase (LDH), flow cytometry and ELISA assays. The association between miR­363­3p and programmed cell death 6­interacting protein (PDCD6IP) was further confirmed using luciferase reporter assay. Our data revealed that the expression level of miR­363­3p was significantly downregulated after OGD/R induction. Overexpression of miR­363­3p markedly suppressed OGD/R­induced cell injury, as reflected by attenuated cell viability, reduced apoptosis, LDH activity and pro­inflammatory cytokine levels. Mechanistically, PDCD6IP was confirmed as the target of miR­363­3p. Furthermore, PDCD6IP knockdown imitated, while overexpression reversed the effects of miR­363­3p overexpression on OGD/R­induced cell injury. Collectively, miR­363­3p could attenuate OGD/R­induced cell injury by alleviating apoptosis and inflammation, which may be mediated, at least in part, via inhibition of PDCD6IP.

Natural compounds modulate the autophagy with potential implication of stroke.

Stroke is considered a leading cause of mortality and neurological disability, which puts a huge burden on individuals and the community. To date, effective therapy for stroke has been limited by its complex pathological mechanisms. Autophagy refers to an intracellular degrading process with the involvement of lysosomes. Autophagy plays a critical role in maintaining the homeostasis and survival of cells by eliminating damaged or non-essential cellular constituents. Increasing evidence support that autophagy protects neuronal cells from ischemic injury. However, under certain circumstances, autophagy activation induces cell death and aggravates ischemic brain injury. Diverse naturally derived compounds have been found to modulate autophagy and exert neuroprotection against stroke. In the present work, we have reviewed recent advances in naturally derived compounds that regulate autophagy and discussed their potential application in stroke treatment.

Compound K inhibits autophagy-mediated apoptosis induced by oxygen and glucose deprivation/reperfusion via regulating AMPK-mTOR pathway in neurons.

AIMS: Oxygen and glucose deprivation and reperfusion (OGD/R) injury contributes to the pathophysiology after ischemic stroke, which needs to urgently develop treatment strategies. Previous studies have demonstrated that autophagy in reperfusion period exerted adverse effects on the cerebral ischemic injury. Ginsenoside monomer compound K (CK) is the main intestinal metabolite of ginseng that exerts the pharmacological activities and has a protective effect against cerebral OGD/R injury. However, the specific molecular mechanism of CK protects against OGD/R injury in neurons is still unclear. MATERIALS AND METHODS: In this study, cell viability, reactive oxygen species (ROS) generation, Ca2+ overload, mitochondrial membrane potential depolarization, autophagy and apoptosis were investigated in OGD/R-induced neuronal cells injury after pretreatment with CK and in combination with BML-275 or rapamycin. KEY FINDINGS: Our study found that pretreatment with CK protected neurons against OGD/R injury by increasing cell viability and decreasing the ROS generation, mitochondrial damage, and Ca2+ overload. Moreover, CK cut down autophagy-mediated apoptosis via promoting the process of forming autophagosomes into phagocytic precursors. Furthermore, our study clarified the neuroprotective of CK against OGD/R-induced neural autophagy and apoptosis through the regulation of the AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway. SIGNIFICANCE: Taken together, our study provides credible experimental evidence and explains the potential molecular mechanism of CK as one of the main bioactive ingredients of ginseng for the treatment of cerebral ischemia/reperfusion injury.

SIRT1 Protects Against Apoptosis by Promoting Autophagy in the Oxygen Glucose Deprivation/Reperfusion-Induced Injury.

Silent information regulator 1 (SIRT1) contributes to cellular regulation. Previous studies have reported SIRT1 to be abnormally expressed in the ischemic penumbra of cerebral ischemia/reperfusion (I/R) injury rat model. We investigated the effect of SIRT1 on oxygen and glucose deprivation/reperfusion (OGD/R) cell injury. Over-expressed or silenced SIRT1 pheochromocytoma 12 (PC12) cells were exposed to an in-vitro OGD/R injury. Western blot, TUNEL staining and immunofluorescence analyses were performed to assess apoptosis and autophagy. We found autophagy and apoptosis to be up-regulated and down-regulated, respectively, following the over-expression of SIRT1 in the OGD/R-induced PC12 cells. We also found the silencing of SIRT1 to culminate in the down-regulation and up-regulation of autophagy and apoptosis, respectively. On the basis of our results, we surmise that SIRT1 can promote autophagy and inhibit apoptosis in-vitro, and thus exhibit potential neuroprotection against OGD/R-induced injury. This could facilitate in the development of therapeutic approaches for cerebral I/R injury.

Stigmasterol protects human brain microvessel endothelial cells against ischemia-reperfusion injury through suppressing EPHA2 phosphorylation / 中国天然药物

Stigmasterol is a plant sterol with anti-apoptotic, anti-oxidative and anti-inflammatory effect through multiple mechanisms. In this study, we further assessed whether it exerts protective effect on human brain microvessel endothelial cells (HBMECs) against ischemia-reperfusion injury and explored the underlying mechanisms. HBMECs were used to establish an in vitro oxygen and glucose deprivation/reperfusion (OGD/R) model, while a middle cerebral artery occlusion (MCAO) model of rats were constructed. The interaction between stigmasterol and EPHA2 was detected by surface plasmon resonance (SPR) and cellular thermal shift assay (CETSA). The results showed that 10 μmol·L-1 stigmasterol significantly protected cell viability, alleviated the loss of tight junction proteins and attenuated the blood-brain barrier (BBB) damage induced by OGD/R in thein vitro model. Subsequent molecular docking showed that stigmasterol might interact with EPHA2 at multiple sites, including T692, a critical gatekeep residue of this receptor. Exogenous ephrin-A1 (an EPHA2 ligand) exacerbated OGD/R-induced EPHA2 phosphorylation at S897, facilitated ZO-1/claudin-5 loss, and promoted BBB leakage in vitro, which were significantly attenuated after stigmasterol treatment. The rat MCAO model confirmed these protective effects in vivo. In summary, these findings suggest that stigmasterol protects HBMECs against ischemia-reperfusion injury by maintaining cell viability, reducing the loss of tight junction proteins, and attenuating the BBB damage. These protective effects are at least meditated by its interaction with EPHA2 and inhibitory effect on EPHA2 phosphorylation.

Effect of asiaticoside on OGD/R induced injury of H9C2 cardiomyocytes based on PI3K/Akt/Beclin-1 signaling pathway / 药学学报

In order to investigate the effects of asiaticoside (Ass) on H9C2 cardiomyocytes, the present study examined the potential intervention of Ass on the proliferation and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/Bcl-2 homology domain protein (Beclin-1) signaling pathway in H9C2 cardiomyocytes following oxygen and glucose deprivation/reperfusion (OGD/R) injury. H9C2 cardiomyocytes were selected as the research objects, and the activity of H9C2 was detected by cell counting kit-8 (CCK-8). H9C2 cells were divided into control group, OGD/R group, Ass low concentration group (10 μmol·L-1), Ass high concentration group (80 μmol·L-1) and Ass high concentration + chloroquine group (80 μmol·L-1 + 50 μmol·L-1). The control group was cultured under normal conditions, and the other groups were treated with oxygen and glucose deprivation for 4 h and reperfusion for 2 h. The activity and content of aspartic aminotransferase (AST), lactate dehydrogenase (LDH) and creatine kinase (CK) in the supernatant of H9C2 cardiomyocytes were detected by enzyme-linked immunosorbent assay. Autophagy staining assay kit with monodansylcadaverine (MDC) method to observe cellular autophagy; molecular docking technique to identify the molecular targets of Ass. Immunofluorescence was used to observe the effect of the drug on cell number. The expression levels of PI3K, Akt, selective autophagy adaptor protein (P62) and Beclin-1 were detected by Western blot. Compared with OGD/R group, Ass group had a protective effect from 10-80 μmol·L-1, and the activities and contents of AST, LDH and CK were decreased. The protein expression levels of PI3K, Akt, P62 and Beclin-1 were decreased. Compared with the administration group, the activities and contents of AST, LDH and CK in Ass high-concentration + chloroquine group were significantly decreased, and the protein expression levels of PI3K, Akt, Beclin-1 and P62 were significantly decreased. Immunofluorescence showed that the inhibitor group and each administration group had different degrees of protective effect compared with the model group. Asiaticoside can reduce the injury of H9C2 cardiomyocyte induced by OGD/R, reduce the content of AST, LDH and CK, reduce the expression level of P62 protein, and reduce autophagy, which may be closely related to the inhibition of PI3K/Akt/Beclin-1 signaling pathway activation.

Mitophagy mediated by ligustilide relieves OGD/R-induced injury in HT22 cells / 中国中药杂志

Mitochondrion, as the main energy-supply organelle, is the key target region that determines neuronal survival and death during ischemia. When an ischemic stroke occurs, timely removal of damaged mitochondria is very important for improving mitochondrial function and repairing nerve damage. This study investigated the effect of ligustilide(LIG), an active ingredient of Chinese medicine, on mitochondrial function and mitophagy based on the oxygen and glucose deprivation/reperfusion(OGD/R)-induced injury model in HT22 cells. By OGD/R-induced injury model was induced in vitro, HT22 cells were pre-treated with LIG for 3 h, and the cell viability was detected by the CCK-8 assay. Immunofluorescence and flow cytometry were used to detect indicators related to mitochondrial function, such as mitochondrial membrane potential, calcium overload, and reactive oxygen species(ROS). Western blot was used to detect the expression of dynamin-related protein 1(Drp1, mitochondrial fission protein) and cleaved caspase-3(apoptotic protein). Immunofluorescence was used to observe the co-localization of the translocase of outer mitochondrial membrane 20(TOMM20, mitochondrial marker) and lysosome-associated membrane protein 2(LAMP2, autophagy marker). The results showed that LIG increased the cell viability of HT22 cells as compared with the conditions in the model group. Furthermore, LIG also inhibited the ROS release, calcium overload, and the decrease in mitochondrial membrane potential in HT22 cells after OGD/R-induced injury, facilitated Drp1 expression, and promoted the co-localization of TOMM20 and LAMP2. The findings indicate that LIG can improve the mitochondrial function after OGD/R-induced injury and promote mitophagy. When mitophagy inhibitor mdivi-1 was administered, the expression of apoptotic protein increased, suggesting that the neuroprotective effect of LIG may be related to the promotion of mitophagy.

Regulation of Sestrin2 overexpression in mitochondrial fission in glucose and oxygen deprivation/recovery SH-SY5Y cell model / 中华神经医学杂志

Objective:To investigate the role of Sestrin2 overexpression in regulating mitochondrial fission and its mechanism in human neuroblastoma SH-SY5Y cell model of glucose and oxygen deprivation/recovery (OGD/R). Methods:(1) SH-SY5Y cells were divided into normal control group, OGD/R group, Vector group, and Sestrin2 overexpression group; Sestrin2 overexpression or empty vector stable cell lines in the Sestrin2 overexpression group and Vector group were constructed by lentivirus infection; cells in the later 3 groups were subjected to oxygen-glucose deprivation (OGD) for 4 h followed by restoration of O 2 supply for 18 h. The cell survival rate was detected by cell counting kit (CCK)-8 assay. The protein levels of Sestrin2, dynamin-related protein 1 (Drp1), mitochondrial fission protein 1 (Fis1), B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), Kelch-like ECH-related protein 1 (Keap1) in the cytoplasm and nuclear factor E2-related factor (Nrf2) in the nucleus were detected by Western blotting. The mitochondria ultrastructure was observed by transmission electron microscope. The Nrf2 nuclear translocation was detected by immunofluorescence staining. (2) Cell lines with Sestrin2 overexpression were divided into Sestrin2 overexpression group, Brusatol+ Sestrin2 overexpression group, and DMSO+ Sestrin2 overexpression group. Cells in the Brusatol+ Sestrin2 overexpression group were pretreated with normal medium containing Brusatol (Keap1/Nrf2 pathway inhibitor, final concentration: 100 nmol/L) for 4 h before OGD/R; cells in the DMSO+ Sestrin2 group were pretreated with normal medium containing DMSO (final volume fraction: 0.1%) for 4 h before OGD/R. Cells in these groups were then subjected to OGD for 4 h followed by restoration of O 2 supply for 18 h. The protein levels of Drp1, Fis1, Keap1 in the cytoplasm, and Nrf2 in the nucleus were measured by Western blotting. Results:(1) As compared with those in the OGD/R group, cells in the Sestrin2 overexpression group had significantly increased survival rate (61.33%±1.15% vs. 81.00%±3.00%), significantly up-regulated Bcl-2/Bax ratio (0.467±0.006 vs. 0.880±0.010), significantly decreased Drp1, Fis1 and cytoplasmic Keap1 protein levels (1.089±0.033 vs. 0.865±0.014; 0.829±0.009 vs. 0.350±0.007; 0.967±0.017 vs. 0.881±0.024), and significantly up-regulated nuclear Nrf2 protein level (0.627±0.025 vs. 0.957±0.015, P<0.05). The mitochondrial structure in the Sestrin2 overexpression group under electron microscope was more complete than that in the OGD/R group, and obvious nuclear translocation of Nrf2 was noted. (2) As compared with the Sestrin2 overexpression group, Brusatol+ Sestrin2 overexpression group had significantly decreased nuclear Nrf2 protein level (0.920±0.013 vs. 0.627±0.035), and statistically increased Drp1 and Fis1 protein levels (0.994±0.020 vs. 1.084±0.005; 0.728±0.010 vs. 0.906±0.022, P<0.05). Conclusion:Sestrin2 overexpression could suppress mitochondrial fission, reduce cell apoptosis, and attenuate OGD/R injury of SH-SY5Y cells by activating Keap1/Nrf2 pathway via down-regulating cytoplasmic Keap1 protein level and promoting Nrf2 nuclear translocation.

Effect of ligustilide on oxygen and glucose deprivation/reperfusion-induced mitochondria fission in PC12 cells / 中国中药杂志

This study aimed to investigate the effect and mechanism of ligustilide, the main active ingredient in Ligusticum wallichii, on mitochondria fission after PC12 cell injury induced by oxygen and glucose deprivation/reperfusion(OGD/R). In the experiment, an OGD/R model was established in vitro, and PC12 cells were pre-treated with ligustilide for 3 h, and then the cell viability was detected by CCK-8 method. The effect of different concentrations of ligustilide on the morphology of PC12 cells after OGD/R injury was observed under an inverted microscope. Transmission electron microscopy was used to observe the mitochondrial fission of PC12 cells after OGD/R injury. DCFH-DA immunofluorescence staining method was used to detect intracellular reactive oxygen species(ROS) changes. Changes in mitochondria membrane potential(MMP) were detected by flow cytometry. Hochest 33258 was used to observe the apoptosis of PC12 cells. Western blot was used to detect changes in cytochrome C(Cyt C) content in mitochondria and cytoplasm, and mitochondrial fission-related proteins Drp 1 and Fis 1. All results showed that compared with the model group, ligustilide significantly increased the survival rate of PC12 cells and the number of cells. Further experiments showed that ligustilide inhibited the release of ROS and decline of mitochondrial membrane potential in PC12 cells after OGD/R injury. Moreover, ligustilide reduced the release of Cyt C and promoted the expressions of Drp1 and Fis1 in mitochondrial fission proteins. Verification experiments showed that mitochondrial fission inhibitor mdivi-1 decreased cell survival rate and inhibited fission. The results indicated that ligustilide exerted neuro-protective effects by promoting mitochondrial fission and reducing cell damage. It preliminary proves that the mechanism of ligustilide on ischemic brain injury may be related to the promotion of mitochondrial fission and the maintenance of cell homeostasis.

Ventral tegmental area/substantia nigra and prefrontal cortex rodent organotypic brain slices as an integrated model to study the cellular changes induced by oxygen/glucose deprivation and reperfusion: effect of neuroprotective agents.

Unveiling the roles of distinct cell types in brain response to insults is a partially unsolved challenge and a key issue for new neuroreparative approaches. In vivo models are not able to dissect the contribution of residential microglia and infiltrating blood-borne monocytes/macrophages, which are fundamentally undistinguishable; conversely, cultured cells lack original tissue anatomical and functional complexity, which profoundly alters reactivity. Here, we tested whether rodent organotypic co-cultures from mesencephalic ventral tegmental area/substantia nigra and prefrontal cortex (VTA/SN-PFC) represent a suitable model to study changes induced by oxygen/glucose deprivation and reperfusion (OGD/R). OGD/R induced cytotoxicity to both VTA/SN and PFC slices, with higher VTA/SN susceptibility. Neurons were highly affected, with astrocytes and oligodendrocytes undergoing very mild damage. Marked reactive astrogliosis was also evident. Notably, OGD/R triggered the activation of CD68-expressing microglia and increased expression of Ym1 and Arg1, two markers of "alternatively" activated beneficial microglia. Treatment with two well-known neuroprotective drugs, the anticonvulsant agent valproic acid and the purinergic P2-antagonist PPADS, prevented neuronal damage. Thus, VTA/SN-PFC cultures are an integrated model to investigate OGD/R-induced effects on distinct cells and easily screen neuroprotective agents. The model is particularly adequate to dissect the microglia phenotypic shift in the lack of a functional vascular compartment.

Modulating autophagy affects neuroamyloidogenesis in an in vitro ischemic stroke model.

AIMS: To explore the effects of modulating autophagy on neuroamyloidogenesis in an ischemic stroke model of cultured neuroblastoma 2a (N2a)/Amyloid precursor protein (APP)695 cells. METHODS: The ischemic stroke model of N2a/APP695 cells was made by 6h oxygen-glucose deprivation/12h reperfusion (OGDR). Drug administration of 3-methyladenine (3-MA), rapamycin or dl-3-n-butylphthalide (NBP) was started at the beginning of the OGDR and lasted until the end of reperfusion, in order to explore their effects on N2a/APP695 cells under OGDR conditions. Then the cells were incubated in the drug-free and full culture medium under normoxic conditions for 12h. Cell viability and injury were investigated. The key proteins of nuclear factor kappa B (NF-κB) pathway and a key component of autophagy Beclin 1 were detected by Western blotting; immunofluorescence double-staining of amyloid-ß (Aß)1-42 with Beclin 1 was performed to investigate their cellular co-localization relationship; ß-secretase and γ-secretase activity assay and Aß1-42 enzyme-linked immunosorbent assay were performed to investigate the amyloidogenesis. RESULTS: The results showed that, OGDR enhanced cell injury, autophagy activity, neuroinflammation and Aß generation in N2a/APP695 cells; down-regulating autophagy by 3-MA and NBP increased cell viability, decreased lactate dehydrogenase (LDH) production, inhibited the activation of NF-κB pathway, suppressed ß- and γ-secretase activities and Aß generation; while up-regulating autophagy by rapamycin got the opposite results; immunofluorescence double-staining results showed elevated Aß1-42(+) signal was co-localized with Beclin 1(+) signal. CONCLUSION: Our data suggested that down-regulating autophagy may inhibit ischemia-induced neuroamyloidogenesis via suppressing the activation of NF-κB pathway. This study might help us to find a new therapeutic strategy to prevent brain ischemic damage and depress the risk of post-stroke dementia.