Ischemia-induced Oxidative Stress Research Articles

Neuroprotective Effects of Chaperonin Containing TCP1 Subunit 2 (CCT2) on Motor Neurons Following Oxidative or Ischemic Stress.

Chaperonin containing TCP1 (CCT) is an essential protein that controls proteostasis following spinal cord damage. In particular, CCT2 plays an important role in neuronal death in various neurological disorders; however, few studies have investigated the effects of CCT2 on ischemic damage in the spinal cord. In the present study, we synthesized a cell-permeable Tat-CCT2 fusion protein and observed its effects on H2O2-induced oxidative damage in NSC34 motoneuron-like cells and in the spinal cord after ischemic injury. Tat-CCT2, but not its control protein CCTs, was delivered into NSC34 cells in a concentration- and incubation time-dependent manner, and a clear cytosolic location of the delivered protein was observed. In addition, the delivered protein gradually degraded, and nearly control levels were observed 24h after Tat-CCT2 treatment. Tat-CCT2 treatment significantly ameliorated 200 µM H2O2-induced neuronal damage in NSC34 cells at 8.0 µM protein treatment. Additionally, Tat-CCT2 significantly ameliorated H2O2-induced reactive oxygen species formation and DNA fragmentation. In the rabbit spinal cord, Tat-CCT2 was efficiently delivered into the spinal cord 4h after 0.125mg/kg protein treatment. In addition, treatment with Tat-CCT2 significantly improved the neurological scores based on the Tarlov criteria 24 and 72h after ischemia/reperfusion. Moreover, the number of surviving neurons in the ventral horn of the spinal cord was significantly increased in the Tat-CCT2-treated group 3 and 7 days after ischemia compared to vehicle-treated group. Treatment with Tat-CCT2 alleviated the ischemia-induced oxidative stress and ferroptosis-related factor (malondialdehyde, 8-iso-prostaglandin F2α, and high mobility group box 1) and pro-inflammatory cytokine (interleukin-1β, interleukin-6, and tumor necrosis factor-α) releases in the ventral horn of the spinal cord 8 and 24h after ischemia/reperfusion. In addition, Tat-CCT2 treatment significantly ameliorated ischemia-induced microglial activation in the ventral horn of spinal cord 24h after reperfusion. These results suggest that Tat-CCT2 mitigates ischemia-induced neuronal damage in the spinal cord.

Extracts from Dendropanax morbifera leaves ameliorates cerebral ischemia-induced hippocampal damage by reducing oxidative damage in gerbil

AimIn this study, we investigated the effects of Dendropanax morbifera extract (DME) on neuroprotection against ischemic damage in gerbils. MethodsDME (100 or 300 mg/kg) was orally administered to gerbils for three weeks, and 2 h after the last DME treatment, transient forebrain ischemia in the common carotid arteries was induced for 5 min. The forebrain ischemia-related cognitive impairments were assessed by spontaneous motor activity and passive avoidance test one and four days after ischemia, respectively. In addition, surviving and degenerating neurons were morphologically confirmed by neuronal nuclei immunohistochemical staining and Fluoro-Jade C staining, respectively, four days after ischemia. Changes of glial morphology were visualized by immunohistochemical staining for each marker such as glial fibrillary acidic protein and ionized calcium-binding protein. Oxidative stress was determined by measurements of dihydroethidium, O2· (formation of formazan) and malondialdehyde two days after ischemia. In addition, glutathione redox system such as reduced glutathione, oxidized glutathione levels, glutathione peroxidase, and glutathione reductase activities were measured two days after ischemia. ResultsSpontaneous motor activity monitoring and passive avoidance tests showed that treatment with 300 mg/kg DME, but not 100 mg/kg, significantly alleviated ischemia-induced memory impairments. In addition, approximately 67 % of mature neurons survived and 29.3 % neurons were degenerated in hippocampal CA1 region four days after ischemia, and ischemia-induced morphological changes in astrocytes and microglia were decreased in the CA1 region after 300 mg/kg DME treatment. Furthermore, treatment with 300 mg/kg DME significantly ameliorated ischemia-induced oxidative stress, such as superoxide formation and lipid peroxidation, two days after ischemia. In addition, ischemia-induced reduction of the glutathione redox system in the hippocampus, assessed two days after the ischemia, was ameliorated by treatment with 300 mg/kg DME. These suggest that DME can potentially reduce ischemia-induced neuronal damage through its antioxidant properties.

Aldehyde Dehydrogenase 2 Preserves Mitochondrial Function in the Ischemic Heart: A Redox-dependent Mechanism for AMPK Activation by Thioredoxin-1.

Aldehyde dehydrogenase 2 (ALDH2) protects the ischemic heart by activating adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling. However, the molecular mechanisms linking ALDH2 and AMPK signaling are not fully understood. This study aimed to explore the potential mechanisms linking ALDH2 and AMPK in myocardial ischemic injury. An ischemic model was established by ligating the left anterior descending coronary artery in rats. The overexpression or knockdown of ALDH2 in H9c2 cells treated with oxygen-glucose deprivation was obtained through lentivirus infection. Transferase-mediated dUTP nick-end labeling was used to evaluate apoptosis in an ischemic rat model and oxygen-glucose deprivation cells. ALDH2 activity, mitochondrial oxidative stress markers, adenosine triphosphate, respiratory control ratio, and cell viability in H9c2 cells were evaluated using a biological kit and 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide. Protein expression of ALDH2 , 4-hydroxynonenal, thioredoxin-1 (Trx-1), and AMPK-proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) signaling pathway was detected through Western blotting. ALDH2 activation reduced ischemic-induced myocardial infarct size and apoptosis. ALDH2 protected mitochondrial function by enhancing mitochondrial respiratory control ratio and adenosine triphosphate production, alleviated mitochondrial oxidative stress, and suppressed myocardial apoptosis. Moreover, ALDH2 attenuated ischemia-induced oxidative stress and maintained Trx-1 levels by reducing 4-hydroxynonenal, thereby promoting AMPK-PGC-1α signaling activation. Inhibiting Trx-1 or AMPK abolished the cardioprotective effect of ALDH2 on ischemia. ALDH2 alleviates myocardial injury through increased mitochondrial biogenesis and reduced oxidative stress, and these effects were achieved through Trx1-mediating AMPK-PGC1-α signaling activation.

Oxidative Stress-mediated Sprouty-related Protein with an EVH1 Domain 1 Down-regulation Contributes to Resisting Oxidative Injury in Microglia

Microglia play an ambiguous role in injury or repair after ischemia–reperfusion, and the induced oxidative stress serves as an important signal, mediates direct toxicity to nerve cells, and eventually simulates complex physiological processes such as activation of microglia to repair the damaged area. Herein, we show that sprouty-related protein with an EVH1 domain 1 (SPRED1) may act as a regulatory node in this phenomenon. The ischemic brain of an ischemia–reperfusion rat model constructed by middle cerebral artery occlusion (MCAO) showed an increase in oxidative stress and downregulation of SPRED1 expression. Hydrogen peroxide (H2O2)-simulated oxidative damage exerted a fluctuating regulatory effect on SPRED1 level in BV2 microglia, which is highly consistent with its regulatory effect on nuclear factor kappa B (NF-κB) transcription factor p65. Interestingly, SPRED1 overexpressed in BV2 cells did not exert any regulatory effect on p38 mitogen-activated protein kinase (MAPK), NF-κB p65, and pro-inflammatory cytokines. However, treatment of BV2 cells overexpressing SPRED1 with H2O2 led to significant changes in the above phenomena as well as their viability and apoptosis. In the absence of H2O2 induction, SPRED overexpression alone did not mediate such an effect. These findings indicate that SPRED1 tends to maintain intracellular homeostasis of signals, but the oxidative stress derived from ischemia-reperfusion can easily degrade SPRED1 and consequently re-activate these restricted signals and alter the behavior of microglia. Thus, our study reveals a novel role of SPRED1 in microglia in response to cerebral ischemia-induced oxidative stress.

Enhancing the Neuroprotection Potential of Edaravone in Transient Global Ischemia Treatment with Glutathione- (GSH-) Conjugated Poly(methacrylic acid) Nanogel as a Promising Carrier for Targeted Brain Drug Delivery.

Ischemic stroke is the most common among various stroke types and the second leading cause of death, worldwide. Edaravone (EDV) is one of the cardinal antioxidants that is capable of scavenging reactive oxygen species, especially hydroxyl molecules, and has been already used for ischemic stroke treatment. However, poor water solubility, low stability, and bioavailability in aqueous media are major EDV drawbacks. Thus, to overcome the aforementioned drawbacks, nanogel was exploited as a drug carrier of EDV. Furthermore, decorating the nanogel surface with glutathione as targeting ligands would potentiate the therapeutic efficacy. Nanovehicle characterization was assessed with various analytical techniques. Size (199 nm, hydrodynamic diameter) and zeta potential (-25 mV) of optimum formulation were assessed. The outcome demonstrated a diameter of around 100 nm, sphere shape, and homogenous morphology. Encapsulation efficiency and drug loading were determined to be 99.9% and 37.5%, respectively. In vitro drug release profile depicted a sustained release process. EDV and glutathione presence in one vehicle simultaneously made the possibility of antioxidant effects on the brain in specific doses, which resulted in elevated spatial memory and learning along with cognitive function in Wistar rats. In addition, significantly lower MDA and PCO and higher levels of neural GSH and antioxidant levels were observed, while histopathological improvement was approved. The developed nanogel can be a suited vehicle for drug delivery of EDV to the brain and improve ischemia-induced oxidative stress cell damage.

Therapeutic Potentials of MicroRNA-126 in Cerebral Ischemia.

Stroke is a leading cause of death and disability worldwide. It is among the most common neurological disorders with an 8-10% lifetime risk. Ischemic stroke accounts for about 85% of all strokes and damages the brain tissue via various damaging mechanisms. Following cerebral ischemia, the disrupted blood-brain barrier (BBB) leads to cerebral edema formation caused by activation of oxidative stress, inflammation, and apoptosis, targeting primarily endothelial cells. Activation of the protective mechanisms might favor fewer damages to the neural tissue. MicroRNA (miR)-126 is an endothelial cell-specific miR involved in angiogenesis. MiR-126 orchestrates endothelial progenitor cell functions under hypoxic conditions and could inhibit ischemia-induced oxidative stress and inflammation. It alleviates the BBB disruption by preventing an augment in matrix metalloproteinase level and halting the decrease in the junctional proteins, including zonula occludens-1 (ZO-1), claudin-5, and occludin levels. Moreover, miR-126 enhances post-stroke angiogenesis and neurogenesis. This work provides a therapeutic perspective for miR-126 as a new approach to treating cerebral ischemia.

Intranasal administration of β-1, 3-galactosyltransferase 2 confers neuroprotection against ischemic stroke by likely inhibiting oxidative stress and NLRP3 inflammasome activation.

Ischemic stroke is one of the major causes of morbidity and mortality. The β-1, 3-galactosyltransferase 2 (B3galt2), a member of β-1, 3-galactosyltransferase family, is playing a vital role in the pathological process of cerebral ischemic injury, but its underlying mechanisms remain unclear. In the present study, we examined the involvement of oxidative stress and NLRP3 inflammasome activation in the neuroprotective effect of B3galt2. Cerebral ischemia/reperfusion (I/R) injury was simulated in a mouse middle cerebral artery occlusion (MCAO) model. Recombinant human B3galt2 (rh-B3galt2) was administered intranasally 1h post MCAO, and TGF-β1-siRNA was administered intracerebroventricularly 24 h before MCAO. Outcome measures included brain infarct volume, neurological function, blood-brain barrier (BBB) permeability, neuronal apoptosis, oxidative stress, and the inflammatory response. First, we found that rh-B3galt2 significantly alleviated brain infarct volume and BBB permeability, improved neurological function, and attenuated I/R-induced neuron apoptosis and oxidative stress. Furthermore, rh-B3galt2 attenuated pro-inflammatory cytokines, NF-κB, IL-6, TNF-α, and IL-1β, and inhibited NLRP3 inflammasome activation. Finally, inhibition of TGF-β1 by TGF-β1-siRNA abolished the anti-oxidative and anti-inflammatory effects of rh-B3galt2 in mice after I/R. Collectively, our study demonstrated that rh-B3galt2 exerts neuroprotective effects by regulating cerebral ischemia-induced oxidative stress and NLRP3 inflammasome, which is mainly dependent on the heightening of the TGF-β1 pathway. Thus, B3galt2 might be considered a new therapeutic target for ischemic stroke treatment.

Chlorpromazine and Promethazine (C+P) Reduce Brain Injury after Ischemic Stroke through the PKC-δ/NOX/MnSOD Pathway.

Cerebral ischemia-reperfusion (I/R) incites neurologic damage through a myriad of complex pathophysiological mechanisms, most notably, inflammation and oxidative stress. In I/R injury, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) produces reactive oxygen species (ROS), which promote inflammatory and apoptotic pathways, augmenting ROS production and promoting cell death. Inhibiting ischemia-induced oxidative stress would be beneficial for reducing neuroinflammation and promoting neuronal cell survival. Studies have demonstrated that chlorpromazine and promethazine (C+P) induce neuroprotection. This study investigated how C+P minimizes oxidative stress triggered by ischemic injury. Adult male Sprague-Dawley rats were subject to middle cerebral artery occlusion (MCAO) and subsequent reperfusion. 8 mg/kg of C+P was injected into the rats when reperfusion was initiated. Neurologic damage was evaluated using infarct volumes, neurological deficit scoring, and TUNEL assays. NOX enzymatic activity, ROS production, protein expression of NOX subunits, manganese superoxide dismutase (MnSOD), and phosphorylation of PKC-δ were assessed. Neural SHSY5Y cells underwent oxygen-glucose deprivation (OGD) and subsequent reoxygenation and C+P treatment. We also evaluated ROS levels and NOX protein subunit expression, MnSOD, and p-PKC-δ/PKC-δ. Additionally, we measured PKC-δ membrane translocation and the level of interaction between NOX subunit (p47phox) and PKC-δ via coimmunoprecipitation. As hypothesized, treatment with C+P therapy decreased levels of neurologic damage. ROS production, NOX subunit expression, NOX activity, and p-PKC-δ/PKC-δ were all significantly decreased in subjects treated with C+P. C+P decreased membrane translocation of PKC-δ and lowered the level of interaction between p47phox and PKC-δ. This study suggests that C+P induces neuroprotective effects in ischemic stroke through inhibiting oxidative stress. Our findings also indicate that PKC-δ, NOX, and MnSOD are vital regulators of oxidative processes, suggesting that C+P may serve as an antioxidant.

Involvement of oxidative stress and TRP channels in cerebral ischemia

Abnormalities of intracellular free Ca+2 concentration is caused through activation of mitochondrial membrane depolarization by excessive levels of reactive oxygen species (ROS). In etiology of cerebral ischemia, the abnormalities of intracellular free Ca+2 concentration and excessive productions of ROS play an important role in the pathophysiology of cerebral ischemia (Chinopoulos and Adam-Vizi, 2006). Ca2+ influx occurs through activation of different cation channels. Well-known cations channels in cell membrane are chemical and voltage gated channels. Apart from the well-known cation channels, there is transient receptor potential (TRP) superfamily. The TRP superfamily is containing 28 members in 7 subfamilies in mammalian. Activation and inhibition mechanisms of the TRP channels are very different from the wellknown calcium channels. TRPM2 channel is activated by ADP-ribose NAD+. Another member of TRP superfamily is TRPV1 channel and it is activated several stimuli, including capsaicin, heat (≥43 °C) and acidic pH (≤ 6) (Chinopoulos and Adam-Vizi, 2006; Toda et al, 2019). Both channels are also activated by oxidative stress. Recent data indicated protective roles of some drugs on cerebral ischemia in rodents. One of the drug is duloxetine (DULOX) and it reduced the effects of Ca2+ entry and ROS through inhibition of TRPM2 channel (Toda et al. 2019). Another drug is dexmedetomidine (DEX) and it is an important drug for long-term sedation in intensive care patients, because it induces a rapid response. In addition to the intensive care patients, it has been started to use for sedation and analgesia in emergency medicine patients (McMorrow and Abramo, 2012). Recently, the protective role of DEX through inhibition of TRPM2 and TRPV1 channels on experimental cerebral ischemia in rats was reported (Akpınar et al. 2016). In the oral presentation, I discussed novel effects of TRPM2, TRPV1 and oxidative stress on the cerebral ischemia in rodents and human.  I concluded that the results of current data suggest that antioxidant drugs such as DEX and DULOX treatments reduce cerebral ischemia-induced oxidative stress and intracellular Ca2+ signaling through inhibition of TRPM2 and TRPV1 channels. It seems to that the exact relationship between TRP channel activation and the drugs in cerebral ischemia still remains to be determined. 

Molecular Characteristics of Underactive Bladder

Underactive bladder (UAB) is a common urological problem in elderly patients presenting with urinary retention and lower urinary tract symptoms. UAB causes chronic urinary retention or a large post-void residual urine which is usually difficult to manage. Treatment of UAB is a challenge to urologists. The underlying pathophysiology has not been completely elucidated. Molecular diagnosis for the clinical characteristics of UAB is important for us to understand the pathogenesis and develop new therapeutic modalities. The urodynamic finding of UAB might be detrusor acontractility of low contractility and is often termed detrusor underactivity. UAB is frequently encountered in elderly patients with chronic medical or neurological diseases. The pathophysiology of UAB may involve neurogenic, myogenic, and bladder outlet pathologies. Recent studies also reveal that increased suburothelial inflammation and altered sensory protein expressions in bladder mucosa were prominent in patients with UAB. Impaired urothelial signaling and sensory transduction pathways might be associated with impaired bladder sensation as well as impaired detrusor contractility. In addition, the bladder outlet obstruction, inflammation, or bladder ischemia-induced oxidative stress might also decrease the energy of the detrusor and result in UAB. Neurogenic inhibition, myogenic factor, and psychogenic inhibition might also be the causes for UAB. This article reviews recent researches on the pathophysiology and molecular characteristics of UAB. Neurogenic, myogenic, urotheliogenic, bladder outlet, and psychogenic factors might all contribute to UAB. Comprehensive clinical investigations and basic researches may provide a better understanding and effective treatment for this common but difficult bladder disorder.

Chrysin attenuates global cerebral ischemic reperfusion injury via suppression of oxidative stress, inflammation and apoptosis

Global cerebral ischemia is a leading cause of mortality worldwide. Several biomechanisms play a role in the pathology of cerebral ischemia reperfusion damage, such as oxidative stress, inflammation, apoptosis and excitotoxicity. Chrysin, a natural flavonoid with many important biological activities, was investigated in the present study for its possible neuroprotective properties in a rat model of global ischemia reperfusion. Male Wistar rats were allocated into three groups: sham-operated, ischemia/reperfusion, and chrysin (30 mg/kg) groups. All animals were subjected to ischemia for 15 min followed by reperfusion for 60 min, except for the sham-operated group. Rats were decapitated, then both hippocampi were rapidly excised to evaluate several biomarkers that reflect ischemic injury. The obtained results showed that pre-treatment with chrysin attenuated ischemia-induced oxidative stress by: (i) restoring the glutathione level; and (ii) depressing the levels/activities of thiobarbituric acid reactive substances, the hippocampal NADPH, as well as the xanthine oxidase. Exposure to chrysin also suppressed the inflammation accompanying the ischemia/reperfusion (I/R) damage, through increasing the interleukin-10 level, while decreasing the levels of both interleukin-6 and tumour necrosis factor-alpha. Moreover, an increase in Bcl2 and a decrease in both BAX and Hsp90 levels were recorded following chrysin exposure, which was also accompanied with elevated glutamate and aspartate levels. In conclusion, chrysin has demonstrated an anti-ischemic potential, through attenuation of the mechanisms underlying I/R injury. These data add to the knowledge on the significance of natural flavonoids as neuroprotective agents.

Phenothiazines Enhance the Hypothermic Preservation of Liver Grafts: A Pilot in Vitro Study.

In vitro liver conservation is an issue of ongoing critical importance in graft transplantation. In this study, we investigated the possibility of augmenting the standard pre-transplant liver conservation protocol (University of Wisconsin (UW) cold solution) with the phenothiazines chlorpromazine and promethazine. Livers from male Sprague-Dawley rats were preserved either in UW solution alone, or in UW solution plus either 2.4, 3.6, or 4.8 mg chlorpromazine and promethazine (C+P, 1:1). The extent of liver injury following preservation was determined by alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, the ratio of AST/ALT, morphological changes as assessed by hematoxylin-eosin staining, apoptotic cell death as determined by ELISA, and by expression of the apoptotic regulatory proteins BAX and Bcl-2. Levels of glucose (GLU) and lactate dehydrogenase (LDH) in the preservation liquid were determined at 3, 12, and 24 h after incubation to assess glucose metabolism. Oxidative stress was assessed by levels of superoxide dismutase (SOD), reactive oxygen species (ROS), and malondialdehyde (MDA), and inflammatory cytokine expression was evaluated with Western blotting. C+P augmentation induced significant reductions in ALT and AST activities; the AST/ALT ratio; as well as in cellular swelling, vacuolar degeneration, apoptosis, and BAX expression. These changes were associated with lowered levels of GLU and LDH; decreased expression of SOD, MDA, ROS, TNF-α, and IL-1β; and increased expression of Bcl-2. We conclude that C+P augments hypothermic preservation of liver tissue by protecting hepatocytes from ischemia-induced oxidative stress and metabolic dysfunction. This result provides a basis for improvement of the current preservation strategy, and thus for the development of a more effective graft conservation method.

Roles of dexmedetomidine and calcium signaling in cerebral ischemia: Focus TRP channels

An accumulating body of evidence indicates that abnormalities of intracellular free calcium ([Ca2+]i) concentration is caused by excessive levels of reactive oxygen species (ROS) in rats with cerebral ischemia in play an important role in the pathophysiology of cerebral ischemia (Miyanohara et al. 2015; Belrose and Jackson, 2018). Ca2+ passes cell membrane via different channels such as chemical and voltage gated channels. Apart from the well-known cation channels, there is recently discovered channels namely transient receptor potential (TRP) family. The TRP superfamily is containing 7 subfamilies with 28 members in mammalian. Activation and inhibition mechanisms of the TRP channels are very different from the voltage gated calcium channels. For example, TRPM2 channel is activated by ADP-ribose and oxidative stress, but TRPV1 channel is activated several stimuli, including capsaicin and oxidative stress (Belrose and Jackson, 2018). Dexmedetomidine (DEX) is an important drug for long-term sedation in intensive care patients because it induces a rapid response and is easily controllable. There is some modulator role of DEX on the [Ca2+]i concentration in several neurons (Akpınar et al. 2016). Results of a recent study indicated that DEX induced modulator role on cerebral ischemia-induced ROS, TRPM2 and TRPV1 channel activation in hippocampusof rats. I concluded that the results of recent studies suggest that DEX treatment reduces cerebral ischemiainduced oxidative stress and intracellular Ca2+ signaling through inhibition of TRP channels. It seems to that the exact relationship between TRP channel activation and DEX in cerebral ischemia still remains to be determined.

LanCL1 attenuates ischemia-induced oxidative stress by Sirt3-mediated preservation of mitochondrial function

Lanthionine synthetase C-like protein 1 (LanCL1) is homologous to prokaryotic lanthionine cyclases, and has been shown to have novel functions in neuronal redox homeostasis. A recent study showed that LanCL1 expression was developmental and activity-dependent regulated, and LanCL1 transgene protected neurons against oxidative stress. In the present study, the potential protective effects of LanCL1 against ischemia was investigated in an in vitro model mimicked by oxygen and glucose deprivation (OGD) in neuronal HT22 cells. We found that OGD exposure induced a temporal increase and persistent decreases in the expression of LanCL1 at both mRNA and protein levels. Overexpression of LanCL1 by lentivirus (LV-LanCL1) transfection preserved cell viability, reduced lactate dehydrogenase (LDH) release and attenuated apoptosis after OGD. These protective effects were accompanied by decreased protein radical formation, lipid peroxidation and mitochondrial dysfunction. In addition, LanCL1 significantly stimulated mitochondrial enzyme activities and SOD2 deacetylation in a Sirt3-dependent manner. The results of western blot analysis showed that LanCL1-induced activation of Sirt3 was dependent on Akt-PGC-1α pathway. Knockdown of PGC-1α expression using small interfering RNA (siRNA) or blocking Akt activation using specific antagonist partially prevented the protective effects of LanCL1 in HT22 cells. Taken together, our results show that LanCL1 protects against OGD through activating the Akt-PGC-1α-Sirt3 pathway, and may have potential therapeutic value for ischemic stroke.

A brain-specific isoform of apoptosis-inducing factor 2 attenuates ischemia-induced oxidative stress in HT22 cells

Apoptosis-inducing factor (AIF) is a family of conserved mitochondrial flavoproteins that have both vital and lethal functions in cells. The function and regulation of AIF-1, the original described and most abundant isoform, has been extensively studied, whereas three other AIF isoforms have not been further characterized. Here, we investigated the role of AIF-2, a brain-specific isoform of AIF, in an in vitro ischemia model in neuronal HT22 cells. We showed that AIF-2 was constitutively expressed in HT22 cells, and the oxygen and glucose deprivation (OGD) did not alter AIF-2 expression. Downregulation of AIF-2 with specific siRNA aggravated OGD-induced lactate dehydrogenase (LDH) release, apoptosis and loss of cell viability, whereas overexpression of AIF-2 through lentivirus transfection exerted the opposite effects. In OGD-treated cells, AIF-2 overexpression promoted the endogenous antioxidant enzyme activities, preserved mitochondrial membrane potential (MMP), inhibited cytochrome c release, and thereby prevented reactive oxygen species (ROS) generation and lipid peroxidation. In addition, AIF-2 significantly prevented the OGD-induced AIF-1 translocation from cytoplasm to the nuclei. In view of these considerations, AIF-2 might represent an ideal strategy to avoid AIF-1 associated neurotoxicity, and could be tested against brain ischemia in animal models.

ZL006 protects spinal cord neurons against ischemia-induced oxidative stress through AMPK-PGC-1α-Sirt3 pathway

Spinal cord ischemia (SCI) induces a range of cellular and molecular cascades, including activation of glutamate receptors and downstream signaling. Post-synaptic density protein 95 (PSD-95) links neuronal nitric oxide synthase (nNOS) with the N-methyl-d-aspartic acid (NMDA) receptors to form a ternary complex in the CNS. This molecular complex-mediated cytotoxicity has been implicated in brain ischemia, but its role in SCI has not been determined. The goal of the study was to investigate the potential protective effects of ZL006, a small-molecule inhibitor of the PSD-95/nNOS interaction, in an in vitro SCI model induced by oxygen and glucose deprivation (OGD) in cultured spinal cord neurons. We found that ZL006 reduced OGD-induced lactate dehydrogenase (LDH) release, neuronal apoptosis and loss of cell viability. This protection was accompanied by the preservation of mitochondrial function, as evidenced by reduced mitochondrial oxidative stress, attenuated mitochondrial membrane potential (MMP) loss, and enhanced ATP generation. In addition, ZL006 stimulated mitochondrial enzyme activities and SOD2 deacetylation in a Sirt3-dependent manner. The results of western blot analysis showed that ZL006 increased the activation of AMPK-PGC-1α-Sirt3 pathway, and the beneficial effects of ZL006 was partially abolished by AMPK inhibitor and PGC-1α knockdown. Therefore, our present data showed that, by the AMPK-PGC-1α-Sirt3 pathway, ZL006 protects spinal cord neurons against ischemia through reducing mitochondrial oxidative stress to prevent apoptosis.

Oral administration of grape seed polyphenol extract restores memory deficits in chronic cerebral hypoperfusion rats.

Chronic cerebral hypoperfusion (CCH) has been recognized as an important cause of both vascular dementia and Alzheimer's disease (AD), the two most prominent neurodegenerative diseases causing memory impairment in the elderly. However, an effective therapy for CCH-induced memory impairment has not yet been established. Grape seed polyphenol extract (GSPE) has powerful antioxidant properties and protects neurons and glia during ischemic injury, but its potential use in the prevention of CCH-induced memory impairment has not yet been investigated. Here, CCH-related memory impairment was modeled in rats using permanent bilateral occlusion of the common carotid artery. A Morris water maze task was used to evaluate memory, the levels of acetylcholinesterase, choline acetyltransferase, acetylcholine were used to evaluate cholinergic function, and oxidative stress was assessed by measuring the enzyme activity of superoxide dismutase, glutathione peroxidase, malonic dialdehyde, and catalase. We found that oral administration of GSPE for 1 month can rescue memory deficits. We also found that GSPE restores cholinergic neuronal function and represses oxidative damage in the hippocampus of CCH rats. We propose that GSPE protects memory in CCH rats by reducing ischemia-induced oxidative stress and cholinergic dysfunction. These findings provide a novel application of GSPE in CCH-related memory impairments.

The neuroprotective action of dexmedetomidine on apoptosis, calcium entry and oxidative stress in cerebral ischemia-induced rats: Contribution of TRPM2 and TRPV1 channels.

Dexmedetomidine (DEX) may act as an antioxidant through regulation of TRPM2 and TRPV1 channel activations in the neurons by reducing cerebral ischemia-induced oxidative stress and apoptosis. The neuroprotective roles of DEX were tested on cerebral ischemia (ISC) in the cultures of rat primary hippocampal and DRG neurons. Fifty-six rats were divided into five groups. A placebo was given to control, sham control, and ISC groups, respectively. In the third group, ISC was induced. The DEX and ISC+DEX groups received intraperitoneal DEX (40 μg/kg) 3, 24, and 48 hours after ISC induction. DEX effectively reversed capsaicin and cumene hydroperoxide/ADP-ribose-induced TRPV1 and TRPM2 densities and cytosolic calcium ion accumulation in the neurons, respectively. In addition, DEX completely reduced ISC-induced oxidative toxicity and apoptosis through intracellular reactive oxygen species production and depolarization of mitochondrial membrane. The DEX and ISC+DEX treatments also decreased the expression levels of caspase 3, caspase 9, and poly (ADP-ribose) polymerase in the hippocampus and DRG. In conclusion, the current results are the first to demonstrate the molecular level effects of DEX on TRPM2 and TRPV1 activation. Therefore, DEX can have remarkable neuroprotective impairment effects in the hippocampus and DRG of ISC-induced rats.

Reformulated meat products protect against ischemia-induced cardiac damage.

The protective effects of the antioxidants present in food are of great relevance for cardiovascular health. This study evaluates whether the extracts from reformulated meat products with a reduction in fat and/or sodium content exert a cardioprotective effect against ischemia-induced oxidative stress in cardiomyocytes, compared with non-meat foods. Ischemic damage caused loss of cell viability, increased reactive oxygen species and lipid peroxidation and decreased the antioxidant activity. Pretreatment for 24 h with digested or non-digested extracts from reformulated meat products led to protection against ischemia-induced oxidative damage: increased cell viability, reduced oxidative stress and restored the antioxidant activity. Similar results were obtained using extracts from tuna fish, but not with the extracts of green peas, salad or white beans. These results suggest that reformulated meat products have a beneficial impact in protecting cardiac cells against ischemia, and they may represent a source of natural antioxidants with benefits for cardiovascular health.

A standardized notoginseng extract exerts cardioprotection by attenuating apoptosis under endoplasmic reticulum stress conditions

Panax notoginseng possesses therapeutic potential for cardiovascular disorders. Endoplasmic reticulum (ER) stress plays a critical role in cardiovascular disease. Here we show that a rare ginsenoside-standardized extract (RGSE) from notoginseng exerts cardioprotection via attenuating ER stress-associated apoptosis. A total of 18 ginsenosides with a concentration of 816.75 mg/g were characterized and quantified in RGSE. Ginsenoside Rh4, Rg5, Rk3, and Rk1 were the most abundant. RGSE at 50 and 100 mg/kg significantly attenuated myocardial infarction and improved cardiac function in acute myocardial infarction (AMI). RGSE also prevented myocardial ischemia-induced oxidative stress and apoptosis in vivo and in vitro. In addition, RGSE decreased the overexpression of GRP78, GRP94 and CHOP, and inhibited the phosphorylation of PERK and IRE1α in ER stress. Further investigation revealed that RGSE effectually inactivated TXNIP/NLRP3 signaling pathway in AMI hearts. These observations suggest a novel role for notoginseng in regulating AMI.