Neuroprotective effect of an antioxidant in ischemic brain injury: involvement of neuronal apoptosis

Nebulized Glutathione as a Key Antioxidant for the Treatment of Oxidative Stress in Neurodegenerative Conditions

Glutathione (GSH), a tripeptide synthesized intracellularly, serves as a pivotal antioxidant, neutralizing reactive oxygen species (ROS) and reactive nitrogen species (RNS) while maintaining redox homeostasis and detoxifying xenobiotics. Its potent antioxidant properties, particularly attributed to the sulfhydryl group (-SH) in cysteine, are crucial for cellular health across various organelles. The glutathione-glutathione disulfide (GSH-GSSG) cycle is facilitated by enzymes like glutathione peroxidase (GPx) and glutathione reductase (GR), thus aiding in detoxification processes and mitigating oxidative damage and inflammation. Mitochondria, being primary sources of reactive oxygen species, benefit significantly from GSH, which regulates metal homeostasis and supports autophagy, apoptosis, and ferroptosis, playing a fundamental role in neuroprotection. The vulnerability of the brain to oxidative stress underscores the importance of GSH in neurological disorders and regenerative medicine. Nebulization of glutathione presents a novel and promising approach to delivering this antioxidant directly to the central nervous system (CNS), potentially enhancing its bioavailability and therapeutic efficacy. This method may offer significant advantages in mitigating neurodegeneration by enhancing nuclear factor erythroid 2-related factor 2 (NRF2) pathway signaling and mitochondrial function, thereby providing direct neuroprotection. By addressing oxidative stress and its detrimental effects on neuronal health, nebulized GSH could play a crucial role in managing and potentially ameliorating conditions such as Parkinson's Disease (PD) and Alzheimer's Disease (AD). Further clinical research is warranted to elucidate the therapeutic potential of nebulized GSH in preserving mitochondrial health, enhancing CNS function, and combating neurodegenerative conditions, aiming to improve outcomes for individuals affected by brain diseases characterized by oxidative stress and neuroinflammation.

Targeting cGAS-STING signaling protects retinal ganglion cells from DNA damage-induced cell loss and promotes visual recovery in glaucoma

BACKGROUND

Glaucoma is an optic neurodegenerative disease. Retinal ganglion cells (RGCs) are the fundamental neurons in the trabecular meshwork, and their loss is the main pathological reason for glaucoma. The present study was to investigate mechanisms that regulate RGCs survival.

METHODS

A mouse model of glaucoma was established by injecting hypertonic saline into the limbal veins. RGCs apoptosis was detected by using flow cytometry. Protein expressions in RGCs in response to DNA damage inducer cisplatin treatment were detected by immunofluorescence and western blot. The expressions of inflammatory cytokines were determined using ELISA and real-time PCR.

RESULTS

In the hypertonic saline-injected mice, we found visual function was impaired followed by the increased expression of γH2AX and activation of cGAS-STING signaling. We found that DNA damage inducer cisplatin treatment incurred significant DNA damage, cell apoptosis, and inflammatory response. Mechanistically, cisplatin treatment triggered activation of the cGAS-STING signaling by disrupting mitochondrial function. Suppression of cGAS-STING ameliorated inflammation and protected visual function in glaucoma mice.

CONCLUSIONS

The data demonstrated that cGAS-STING signaling is activated in the damaged retinal ganglion cells, which is associated with increased inflammatory responses, DNA damage, and mitochondrial dysfunction. Targeting the cGAS-STING signaling pathway represents a potential way to alleviate glaucoma-related visual function.

Therapeutic modulation of the phosphatidylinositol 3-kinases (PI3K) pathway in cerebral ischemic injury

The cerebral ischemic reperfusion injury may leads to morbidity and mortality in patients. phosphatidylinositol 3-kinase (PI3K) signaling pathway has been believed to work in association with its downstream targets, other receptors, and pathways that may offer antioxidant, anti-inflammatory, anti-apoptotic effects, neuroprotective role in neuronal excitotoxicity. This review elaborates the mechanistic interventions of the PI3K pathway in cerebral ischemic injury in context to nuclear factor erythroid 2-related factor 2 (Nrf2) regulation, Hypoxia-inducible factor 1 signaling (HIF-1), growth factors, Endothelial NOS (eNOS) proinflammatory cytokines, Erythropoietin (EPO), Phosphatase and tensin homologous protein of chromosome 10 gene (PTEN) signaling, NF-κB/Notch signaling, c-Jun N-terminal kinase (JNK) and Glycogen synthase kinase-3β (GSK-3β) signaling pathway. Evidences showing the activation of PI3K inhibits apoptotic pathway, which results in its neuroprotective effect in ischemic injury. Despite discussing the therapeutic role of the PI3K pathway in treating cerebral ischemic injury, the review also enlighten the selective modulation of PI3K pathway with activators and inhibitors which may provide promising results in clinical and preclinical settings.

Postoperative hemorrhage during the acute phase after direct or combined revascularization for moyamoya disease: risk factors, prognosis, and literature review

OBJECTIVE

Postoperative hemorrhage during the acute phase is rarely observed after revascularization surgery for moyamoya disease (MMD) but can have severe complications. Its risk factors and outcomes are still unclear. The aim of this study was to investigate the predictors of postoperative hemorrhage during the acute phase in MMD and examine the outcomes of the hemorrhage.

METHODS

The authors reviewed the preoperative clinical characteristics and radiographic features of 465 consecutive MMD cases (518 procedures) that had undergone direct or combined bypass surgery at their institution between 2009 and 2015. Patients with postoperative intracerebral hemorrhage (ICH) or ICH plus intraventricular hemorrhage (IVH) during the acute phase were screened, and then the incidence, location, and risk factors of hemorrhage in these patients were analyzed. Short-term and long-term outcomes (modified Rankin Scale scores) for these patients were also collected. Outcomes were compared between patients with and those without postoperative ICH using propensity score analysis to reduce the between-group differences in baseline characteristics.

RESULTS

Postoperative hemorrhage occurred in 11 (2.1%; ICH = 9, IVH = 2) of 518 procedures (mean patient age 39.82 ± 8.8 years). Hemorrhage occurred in the first 24 hours after the operation in 8 cases (72.7%). In the ICH group, most of the hemorrhage sites (77.8%) were located beneath the anastomosed area, and the mean hematoma volume was 16.98 ± 22.45 ml (range 3-57 ml). One case from the ICH group required hematoma evacuation. Among the adult patients (463 procedures [89.4%]), preoperative hypertension (p = 0.008), CT perfusion (CTP) stage > III (p = 0.013), and posterior circulation involvement (p = 0.022) were significantly associated with postoperative ICH. No significant differences between the postoperative ICH group and the no-hemorrhage group were detected in terms of postoperative neurofunctional status at discharge (p = 0.569) or at the last follow-up (p = 1.000). Neither was there a significant difference in future stroke risk (p = 0.538) between these two groups.

CONCLUSIONS

Preoperative hypertension, CTP stage > III, and posterior circulation involvement are independent risk factors for postoperative ICH after direct or combined revascularization for MMD. After appropriate perioperative management, postoperative ICH has no significant correlations with the postoperative short-term and long-term neurofunctional status.

Combination of Scalp Acupuncture with Exercise Therapy Effectively Counteracts Ischemic Brain Injury in Rats

BACKGROUND

Stroke is one of the leading causes of death and disability worldwide. Scalp acupuncture and exercise therapy have been proven as two effective methods for the treatment of stroke. However, their combined action and mechanisms have not been fully elucidated. The present study aimed to investigate the protective effect of scalp acupuncture combined with exercise therapy on neurons in rats with ischemic brain injury.

METHODS

100 rats were randomly divided into 5 groups including sham group, model group, acupuncture group, rehabilitation group, and experimental group (scalp acupuncture combined with exercise therapy). Middle cerebral artery occlusion (MCAO) model in rats was established according to Longa modified suture method to mimic ischemic stroke. The modified Bedexer's neurological function score was used to evaluate the neurological deficits of rats and the brain infarct volume was measured using 2, 3, 5-triphenyl tetrazolium chloride monohydrate (TTC) staining. Moreover, the apoptosis in the hippocampus was detected by western blotting and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The pro-inflammatory cytokines such as interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α), reactive oxygen species (ROS) and superoxide dismutase (SOD) were determined by corresponding kits. Immunohistochemistry or immunofluorescence was performed to detect the expression of brain-derived neurotrophic factor (BDNF), S100β and glial fibrillary acidic protein (GFAP) in the hippocampi of rats.

RESULTS

The neurological deficit score, the expression levels of apoptotic factors such as cleaved caspase-3 and Bax, and the TUNEL-positive cell rate of the experimental group were significantly lower than those of the acupuncture group and the rehabilitation group. However, apoptosis inhibitor Bcl-2 showed downregulated expression in the MCAO model rats but this trend was reverted by single and combinatorial treatments. In addition, the contents of TNF-α, IL-1β and ROS in the acupuncture group and the rehabilitation group were significantly lower than those in the model group, but higher than the experimental group. While the opposite results were obtained in SOD activity. Furthermore, compared with the model group, the ratios of BDNF, S100β, and GFAP-positive cells in the acupuncture, rehabilitation and experimental groups were significantly increased, and the highest ratios were recorded in the experimental group.

CONCLUSIONS

This study demonstrated that scalp acupuncture combined with exercise therapy effectively counteracts ischemic brain injury via the downregulation of pro-inflammatory mediators and ROS, the increased production of the antioxidant enzyme SOD, neurotrophic factor BDNF and astrocyte activities.

Neuroprotective effects of human neural stem cells over-expressing choline acetyltransferase in a middle cerebral artery occlusion model

Stroke is one of the most-devastating brain diseases causing acute death or permanent disability. Although tissue-type plasminogen activator was approved by Food and Drug Administration for early reperfusion of the occluded vessels, oxidative injury may cause extensive brain infarction. Accordingly, there is a need for effective neuroprotection during reperfusion, and stem cell-based therapeutic approaches should fulfill this requirement. We established human neural stem cells (NSCs) encoding gene of choline acetyltransferase (F3.ChAT), an acetylcholine-synthesizing enzyme, and investigated whether infusion of the F3.ChAT cells attenuate the ischemia-reperfusion brain damage in a rat model of middle cerebral artery occlusion (MCAO). F3.ChAT cells were found to produce much higher amounts of ChAT as well as neuroprotective and anti-inflammatory neurotrophins than their parental F3 NSCs. After 2-h occlusion, the artery was reperfused, along with intravenous infusion of the stem cells (1 × 10⁶ cells/rat). Administration of the F3.ChAT cells markedly reduced the infarction volume and improved both the cognitive dysfunction and behavioural deficits of MCAO animals, in which F3.ChAT cells were superior to F3 cells. F3.ChAT cells not only restored microtubule-associated protein-2, a neuronal cytoskeletal protein, and preserved microvessels, but also suppressed lipid peroxidation, pro-inflammatory cytokines, glial fibrillary acidic protein, and intercellular adhesion molecule-1 in the brain tissues. The results demonstrate that early intravenous infusion of NSCs expressing ChAT and neurotrophins attenuate brain and capillary injuries and restore neurobehavioural functions via neuroprotective and anti-inflammatory activities, and that F3.ChAT cells could be a candidate for the neuroprotection and functional recovery of acute stroke patients.

Intracranial Hemorrhage After Superficial Temporal Artery-Middle Cerebral Artery Direct Anastomosis for Adults with Moyamoya Disease

BACKGROUND

Intracranial hemorrhage, such as intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and intraventricular hemorrhage (IVH), is an extremely rare complication after surgical revascularization for moyamoya disease (MMD). However, the incidence, timing, prognosis, possible mechanism, and prevention are not well known.

METHODS

Adult patients with MMD who underwent direct bypass or combined bypass and experienced ICH, SAH, or IVH within 7 days postoperatively were enrolled in this study. The medical records and radiologic findings of these patients, together with their intraoperative video recordings, were reviewed retrospectively.

RESULTS

Direct superficial temporal artery (STA)-middle cerebral artery (MCA) bypass or combined bypass was performed for 222 hemispheres in 193 adult patients with MMD between January 2001 and December 2016. Intracranial hemorrhage occurred perioperatively in 8 hemispheres (3.6%) in 8 patients. The hemorrhages developed immediately after STA-MCA direct anastomosis during surgery in 3 patients. Hemorrhage on computed tomography and neurologic deterioration were also observed immediately postoperatively in 2 patients and during the postoperative period in 3 patients. Although 4 patients received medical management, neurosurgical treatment was needed in the other 4 patients. One patient died, and 6 patients were left with moderate or severe disabilities.

CONCLUSIONS

Intracranial hemorrhage (ICH, IVH, or SAH) after direct bypass for adult patients with MMD is an extremely rare but fatal complication. Although these hemorrhages can be associated with hyperperfusion syndrome, no effective prevention has been established.

Intraoperative dexmedetomidine and postoperative cerebral hyperperfusion syndrome in patients who underwent superficial temporal artery-middle cerebral artery anastomosis for moyamoya disease: A retrospective observational study

Dexmedetomidine, a selective α2-agonist, reduces cerebral blood flow and has neuroprotective effects against cerebral ischemia/reperfusion injury in experimental animals. We examined whether intraoperative dexmedetomidine would reduce the incidence of postoperative cerebral hyperperfusion syndrome (CHS) after superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis in patients with moyamoya disease.The electronic medical records of 117 moyamoya patients who underwent STA-MCA anastomosis were reviewed retrospectively. The patients were divided into 2 groups: 48 patients received intraoperative dexmedetomidine (Group D), while 69 patients did not (Group ND). The incidence (primary outcome), onset, and duration of postoperative CHS were noted.The incidence of postoperative CHS was 45.8% and 40.6% in groups D and ND, respectively (P = 0.708). The duration of postoperative CHS was shorter in group D than in group ND (median [Q1-Q3], 5 [3-7] vs 8 [5-10] days, P = 0.021). There was no significant difference in the onset of CHS between group D and group ND (0 [0-2] vs 1 [0-3] days, P = 0.226).In conclusion, intraoperative dexmedetomidine did not reduce the incidence of postoperative CHS, although it reduced the duration of CHS, in patients who had undergone direct revascularization surgery for moyamoya disease.

Effect of ischemic preconditioning on antioxidant status in the gerbil hippocampal CA1 region after transient forebrain ischemia

Ischemic preconditioning (IPC) is a condition of sublethal transient global ischemia and exhibits neuroprotective effects against subsequent lethal ischemic insult. We, in this study, examined the neuroprotective effects of IPC and its effects on immunoreactive changes of antioxidant enzymes including superoxide dismutase (SOD) 1 and SOD2, catalase (CAT) and glutathione peroxidase (GPX) in the gerbil hippocampal CA1 region after transient forebrain ischemia. Pyramidal neurons of the stratum pyramidale (SP) in the hippocampal CA1 region of animals died 5 days after lethal transient ischemia without IPC (8.6% (ratio of remanent neurons) of the sham-operated group); however, IPC prevented the pyramidal neurons from subsequent lethal ischemic injury (92.3% (ratio of remanent neurons) of the sham-operated group). SOD1, SOD2, CAT and GPX immunoreactivities in the sham-operated animals were easily detected in pyramidal neurons in the stratum pyramidale (SP) of the hippocampal CA1 region, while all of these immunoreactivities were rarely detected in the stratum pyramidale at 5 days after lethal transient ischemia without IPC. Meanwhile, their immunoreactivities in the sham-operated animals with IPC were similar to (SOD1, SOD2 and CAT) or higher (GPX) than those in the sham-operated animals without IPC. Furthermore, their immunoreactivities in the stratum pyramidale of the ischemia-operated animals with IPC were steadily maintained after lethal ischemia/reperfusion. Results of western blot analysis for SOD1, SOD2, CAT and GPX were similar to immunohistochemical data. In conclusion, IPC maintained or increased the expression of antioxidant enzymes in the stratum pyramidale of the hippocampal CA1 region after subsequent lethal transient forebrain ischemia and IPC exhibited neuroprotective effects in the hippocampal CA1 region against transient forebrain ischemia.

Pharmacokinetic Comparison of Scutellarin and Paeoniflorin in Sham-Operated and Middle Cerebral Artery Occlusion Ischemia and Reperfusion Injury Rats after Intravenous Administration of Xin-Shao Formula

Xin-Shao formula is a folk remedy widely used in China to prevent and cure stroke. Cerebral ischemic reperfusion (I/R) injury often takes place during the treatment of stroke. Information about the pharmacokinetic behavior of the remedy under cerebral I/R injury conditions is lacking. The present study aimed to compare the pharmacokinetic properties of scutellarin and paeoniflorin, two major bioactive components of Xin-Shao formula, under physiological state in cerebral I/R injury rats. Neurobehavioral dysfunction was evaluated and cerebral infarcted volume was measured in middle cerebral artery occlusion I/R injury (MCAO) rats. Plasma samples were collected at various time points after a single dose (intravenous, i.v.) of Xin-Shao formula. The levels of plasma scutellarin and paeoniflorin at the designed time points were determined by a UPLC-MS/MS method, and drug concentration versus time plots were constructed to estimate pharmacokinetic parameters. Increase in terminal elimination half-life (t_1/2z) and mean residence time (MRT_(0–t)) of scutellarin as well as elevation in area under the plasma drug concentration-time curve from 0 h to the terminal time point (AUC_(0–t)) and maximum plasma drug concentration (C_max) of paeoniflorin, along with decreased clearance of paeoniflorin and scutellarin as well as reduced apparent volume of distribution (V_z) of paeoniflorin, were observed in MCAO rats, compared with those in sham-operated animals. The elimination of scutellarin and paeoniflorin were reduced in cerebral I/R injury reduced rats.

Green Tea Catechin Prevents Hypoxia/Reperfusion-Evoked Oxidative Stress-Regulated Autophagy-Activated Apoptosis and Cell Death in Microglial Cells

Defective activation and proliferation in microglial cells has been suggested to be associated with the increase of cerebral ischemia/reperfusion injury. We investigated the protection and molecular mechanism of green tea catechin on hypoxia/reperfusion-induced microglial cell injury in vitro. Microglial cells were cultured in hypoxia condition (O2 < 1%) and then re-incubated to the complete normal culture medium (reperfusion). Hypoxia/reperfusion obviously decreased cell viability and induced apoptosis in microglial cells, but not in neuronal cells. Catechin significantly inhibited the hypoxia/reperfusion-induced decreased cell viability and increased reactive oxygen species (ROS) and apoptosis in microglia. The administration of both PI3K/Akt inhibitor LY294002 and mTOR inhibitor rapamycin demonstrated that Akt/mTOR-regulated autophagy was involved in the hypoxia/reperfusion-induced microglia apoptosis/death. Catechin up-regulated the Akt and mTOR phosphorylation and inhibited the hypoxia/reperfusion-induced autophagy in microglia. These results suggest that hypoxia/reperfusion can evoke autophagy-activated microglia apoptosis/death via an ROS-regulated Akt/mTOR signaling pathway, which can be reversed by catechin.

Oenanthe Javanica Extract Protects Against Experimentally Induced Ischemic Neuronal Damage via its Antioxidant Effects

BACKGROUND

Water dropwort (Oenanthe javanica) as a popular traditional medicine in Asia shows various biological properties including antioxidant activity. In this study, we firstly examined the neuroprotective effect of Oenanthe javanica extract (OJE) in the hippocampal cornus ammonis 1 region (CA1 region) of the gerbil subjected to transient cerebral ischemia.

METHODS

Gerbils were established by the occlusion of common carotid arteries for 5 min. The neuroprotective effect of OJE was estimated by cresyl violet staining. In addition, 4 antioxidants (copper, zinc superoxide dismutase [SOD], manganese SOD, catalase, and glutathione peroxidase) immunoreactivities were investigated by immunohistochemistry.

RESULTS

Pyramidal neurons in the CA1 region showed neuronal death at 5 days postischemia; at this point in time, all antioxidants immunoreactivities disappeared in CA1 pyramidal neurons and showed in many nonpyramidal cells. Treatment with 200 mg/kg, not 100 mg/kg, OJE protected CA1 pyramidal neurons from ischemic damage. In addition, 200 mg/kg OJE treatment increased or maintained antioxidants immunoreactivities. Especially, among the antioxidants, glutathione peroxidase immunoreactivity was effectively increased in the CA1 pyramidal neurons of the OJE-treated sham-operated and ischemia-operated groups.

CONCLUSION

Our present results indicate that treatment with OJE can protect neurons from transient ischemic damage and that the neuroprotective effect may be closely associated with increased or maintained intracellular antioxidant enzymes by OJE.

Efficacy, safety, and outcomes in 17 pediatric cases treated with the free radical scavenger edaravone

SUBJECTS

Edaravone is a free radical scavenger with brain protection properties and is recommended by "The Japanese Guidelines for the Management of Stroke 2009" for administration to adult patients, in whom it has been shown to improve neurological deficits after cerebral infarction. However, its dosage and effects have not yet been established in children.

METHODS

Seventeen pediatric patients with cerebral ischemia were administered edaravone at a dose based on body weight from the standard dose given to adults. Functional outcomes were evaluated using mRS and PSOM (modified ranking scale and pediatric stroke outcome scale, respectively).

RESULTS

Immediate post-treatment results were mostly positive, with no liver or renal complications. In some cases, neurological symptoms markedly improved after the administration of edaravone.

CONCLUSIONS

The efficacy of edaravone has not yet been examined in pediatric patients. The results of the present study suggest that edaravone has potential in the treatment of children safely with promising results similar to those in adults.

Panax notoginseng saponin attenuates hypoxia/reoxygenation-induced oxidative stress in cortical neurons

The present study monitored the effect of 2, 10, and 50 mg/L of Panax notoginseng saponin exposure following hypoxia-reoxygenation injury in fetal rat cortical neurons. Results showed that varying doses of Panax notoginseng saponin significantly enhanced the cell viability of neurons, reduced malondialdehyde content, increased superoxide dismutase activity, inhibited mRNA and protein expression of inducible and neuronal nitric oxide synthase, and decreased the release of nitric oxide in hypoxia/reoxygenation injured cells. In particular, 50 mg/L of Panax notoginseng saponin was the most effective dose. These findings suggest that Panax notoginseng saponin can attenuate neuronal oxidative stress injury caused by hypoxia/reoxygenation in a dose-dependent manner.

Resveratrol inhibits oxygen-glucose deprivation-induced MMP-3 expression and cell apoptosis in primary cortical cells via the NF-κB pathway

Resveratrol (Res) or trans-3,4',5-trihydroxystilbene, has been proven to exert neuroprotective effects in cerebral ischemia. The aim of the present study was to investigate whether Res has neuroprotective effects in primary cortical neurons subjected to transient oxygen-glucose deprivation (OGD) via inhibiting the expression of the gene encoding stromelysin-1, also known as matrix metalloproteinase-3 (MMP-3), and via inhibiting cell apoptosis. Primary cortical cells were exposed to OGD, followed by reoxygenation to induce transient ischemia. Res (50 µM) was added into the culture medium during transient ischemia in the presence or absence of the nuclear factor (NF)-κB inhibitor pyrrolidine dithiocarbamate (PDTC; 10 µM) or 500 µM of the nitric oxide (NO) donor NOC-18. Cell viability was assessed using the tetrazolium reduction (MTT) assay. Cell apoptosis was evaluated by flow cytometry. MMP-3 expression was analyzed by western blot and reverse transcription-polymerase chain reaction (RT-PCR), while the levels of inducible NO synthase (iNOS), NF-κB, caspase-3, cleaved caspase-3, B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax) were assayed by western blot. NO was detected using a spectrophotometric method. We found that the cellular viability was significantly reduced by transient OGD and that this effect was reversed by Res treatment. In addition, OGD was shown to induce cell apoptosis, the expression of Bax and the activation of caspase-3, and inhibit the expression of Bcl-2, and these effects were also reversed by Res treatment. Res treatment significantly reduced the level of MMP-3 that was induced by transient OGD, via inhibition of NF-κB expression. In addition, Res inhibited iNOS expression and NO synthesis that were induced by OGD. MMP-3 expression induced by NO was attenuated by Res treatment and was partially restored by exogenous NO using NOC-18. Taken together, these findings indicate that OGD induces apoptosis through canonical apoptosis signaling and by modulating the expression of MMP-3; Res can reverse the OGD-induced MMP-3 expression and cell apoptosis via the NF-κB-iNOS/NO pathway. Therefore, Res may be a promising agent for the treatment of neuronal injury associated with stroke.

Resveratrol protects primary cortical neuron cultures from transient oxygen-glucose deprivation by inhibiting MMP-9

It was recently shown that resveratrol exerts neuroprotective effects against cerebral ischemia in mice. The aim of the present study was to further confirm these effects in in vitro primary cortical neuron cultures with transient oxygen-glucose deprivation (OGD), and to investigate whether these effects are due to the inhibition of matrix metalloproteinase-9 (MMP-9) and of cell apoptosis. Neuronal primary cultures of cerebral cortex were prepared from BALB/c mice embryos (13-15 days). Cells from 14- to 16-day cultures were subjected to OGD for 3 h, followed by 21 h of reoxygenation to simulate transient ischemia. Different doses of resveratrol were added into the culture medium during the simulation of transient ischemia. The effect of the extracellular signal-regulated kinase (ERK) inhibitor U0126 was studied by adding U0126 (5 µg/µl, 4 µl) into the culture medium during transient ischemia; as a control, we used treatment of cells with 50 µM of resveratrol. Cell viability was investigated using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) reduction assay. Cell apoptosis was assessed by flow cytometry. The effects of resveratrol on the expression of MMP-9 were analyzed by western blotting and reverse transcription-polymerase chain reaction (RT-PCR), while the levels of ERK, phosphorylated (p)-ERK, cleaved caspase-3, Bax and Bcl-2 were measured by western blotting. The results of the MTT assay showed that cell viability is significantly reduced by transient OGD. OGD induced cell apoptosis, the expression of Bax and the activation of caspase-3 and ERK, inhibited the expression of Bcl-2 and increased the expression of MMP-9, while these effects were reversed by treatment with resveratrol. The therapeutic efficacy of resveratrol was shown to be dose-dependent, with the most suitable dose range determined at 50-100 µM. Treatment with U0126 inhibited MMP-9 and Bax expression and caspase-3 activation, while it further promoted the expression of the anti-apoptotic molecule Bcl-2, suggesting that resveratrol inhibits MMP-9 expression and cell apoptosis by attenuating the activation of ERK1/2. In conclusion, OGD can induce apoptosis through canonical apoptotic signals and by regulating the expression of MMP-9; the anti-apoptotic activity of resveratrol and its inhibitory effect on MMP-9 expression contribute in the reduced activation of ERK.

The potential therapeutic effect of guanosine after cortical focal ischemia in rats

BACKGROUND AND PURPOSE

Stroke is a devastating disease. Both excitotoxicity and oxidative stress play important roles in ischemic brain injury, along with harmful impacts on ischemic cerebral tissue. As guanosine plays an important neuroprotective role in the central nervous system, the purpose of this study was to evaluate the neuroprotective effects of guanosine and putative cerebral events following the onset of permanent focal cerebral ischemia.

METHODS

Permanent focal cerebral ischemia was induced in rats by thermocoagulation. Guanosine was administered immediately, 1 h, 3 h and 6 h after surgery. Behavioral performance was evaluated by cylinder testing for a period of 15 days after surgery. Brain oxidative stress parameters, including levels of ROS/RNS, lipid peroxidation, antioxidant non-enzymatic levels (GSH, vitamin C) and enzymatic parameters (SOD expression and activity and CAT activity), as well as glutamatergic parameters (EAAC1, GLAST and GLT1, glutamine synthetase) were analyzed.

RESULTS

After 24 h, ischemic injury resulted in impaired function of the forelimb, caused brain infarct and increased lipid peroxidation. Treatment with guanosine restored these parameters. Oxidative stress markers were affected by ischemic insult, demonstrated by increased ROS/RNS levels, increased SOD expression with reduced SOD activity and decreased non-enzymatic (GSH and vitamin C) antioxidant defenses. Guanosine prevented increased ROS/RNS levels, decreased SOD activity, further increased SOD expression, increased CAT activity and restored vitamin C levels. Ischemia also affected glutamatergic parameters, illustrated by increased EAAC1 levels and decreased GLT1 levels; guanosine reversed the decreased GLT1 levels and did not affect the EAAC1 levels.

CONCLUSION

The effects of brain ischemia were strongly attenuated by guanosine administration. The cellular mechanisms involved in redox and glutamatergic homeostasis, which were both affected by the ischemic insult, were also modulated by guanosine. These observations reveal that guanosine may represent a potential therapeutic agent in cerebral ischemia by preventing oxidative stress and excitotoxicity.

Neuroprotective effects of scutellarin and scutellarein on repeatedly cerebral ischemia-reperfusion in rats

Scutellarin had protective effects against neuronal injury, however, there are few studies on the protective effect of scutellarein, which is the main metabolite of scutellarin in vivo. This study investigated whether the neural injury by ischemia/reperfusion would be influenced by different doses of scutellarin and scutellarein. Male Wistar rats were orally administered with scutellarin and scutellarein at the doses of 0.09, 0.17, 0.35, 0.70, 1.40 mmol/kg, respectively; then after six consecutive days, they were subjected to global ischemia by occlusion of the bilateral common carotid arteries (BCCAO). After reperfusion for about 21 h, neurological and histological examinations were performed. The present results showed that scutellarein attenuated neuronal cell damage, reduced cerebral water content, regulated the expression of glutamic acid (Glu), aspartic acid (Asp), glycine (Gly), γ-aminobutyric acid (GABA) and taurine (Tau), and improved the Ca(2+)-ATPase and Na(+),K(+)-ATPase activity. Meanwhile, significant difference was found among various doses of scutellarin and scutellarein. Our studies indicated that scutellarin and scutellarein could improve neuronal injury, and scutellarein had better protective effect than scutellarin in rat cerebral ischemia.

Neuroprotective Activity of Water Soluble Extract fromChorispora bungeanaagainst Focal Cerebral Ischemic/Reperfusion Injury in Mice

The purpose of the present study was to clarify whether the water extract ofChorispora bungeanawas an antioxidant agent against cerebral ischemia/reperfusion (I/R). Our results showed that water extract ofChorispora bungeanatreatment significantly reduced neurological deficit scores, infarct size, MDA and carbonyl contents, and GSH/GSSG ratio compared with the model control group. After being treated byChorispora bungeana, SOD, CAT, and GSH-Px activities remarkably increased.Chorispora bungeanatreatment also improved 8-OHdG expression and cell apoptosis. Our findings indicated that the water extract ofChorispora bungeanapossesses neuroprotective effect which is most likely achieved by antioxidant and antiapoptotic activities.

Oxidative stress and genetic markers of suboptimal antioxidant defense in the aging brain: a theoretical review

Normal aging involves a gradual breakdown of physiological processes that leads to a decline in cognitive functions and brain integrity, yet the onset and progression of decline are variable among older individuals. While many biological changes may contribute to this degree of variability, oxidative stress is a key mechanism of the aging process that can cause direct damage to cellular architecture within the brain. Oligodendrocytes are at a high risk for oxidative damage due to their role in myelin maintenance and production and limited repair mechanisms, suggesting that white matter may be particularly vulnerable to oxidative activity. Antioxidant defense enzymes within the brain, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione-S-transferase (GST), are crucial for breaking down the harmful end products of oxidative phosphorylation. Previous studies have revealed that allele variations of polymorphisms that encode these antioxidants are associated with abnormalities in SOD, CAT, GPx, and GST activity in the central nervous system. This review will focus on the role of oxidative stress in the aging brain and the impact of decreased antioxidant defense on brain integrity and cognitive function. Directions for future research investigations of antioxidant defense genes will also be discussed.

Neuroprotective effect of a new synthetic aspirin-decursinol adduct in experimental animal models of ischemic stroke

Stroke is the second leading cause of death. Experimental animal models of cerebral ischemia are widely used for researching mechanisms of ischemic damage and developing new drugs for the prevention and treatment of stroke. The present study aimed to comparatively investigate neuroprotective effects of aspirin (ASA), decursinol (DA) and new synthetic aspirin-decursinol adduct (ASA-DA) against transient focal and global cerebral ischemic damage. We found that treatment with 20 mg/kg, not 10 mg/kg, ASA-DA protected against ischemia-induced neuronal death after transient focal and global ischemic damage, and its neuroprotective effect was much better than that of ASA or DA alone. In addition, 20 mg/kg ASA-DA treatment reduced the ischemia-induced gliosis and maintained antioxidants levels in the corresponding injury regions. In brief, ASA-DA, a new synthetic drug, dramatically protected neurons from ischemic damage, and neuroprotective effects of ASA-DA may be closely related to the attenuation of ischemia-induced gliosis and maintenance of antioxidants.

Aripiprazole, an atypical antipsychotic drug, improves maturation and complexity of neuroblast dendrites in the mouse dentate gyrus via increasing superoxide dismutases

Apripiprazole (APZ) is well known as an atypical antipsychotic and antidepressant. In the present study, we investigated effects of APZ on cell proliferation and neuronal differentiation in the dentate gyrus (DG) of the adolescent mouse using BruU, Ki-67 and doublecortin (DCX) immunohistochemistry. BruU, Ki-67 and DCX-positive (+) cells were easily detected in the subgranular zone of the DG in the vehicle- and APZ-treated group. We found that in the 8 mg/kg APZ-treated group numbers of Ki-67(+), DCX(+) and BrdU(+)/DCX(+) cells were significantly increased compared with those in the vehicle-treated group. We also found that maturation and complexity of DCX(+) dendrites in the 8 mg/kg APZ-treated group was well improved compared with those in the vehicle-treated group. In addition, markedly decreased lipid peroxidation and increased superoxide dismutase 2 (SOD2) level were observed in the DG of the 8 mg/kg APZ-treated group. Our present findings indicate that APZ can enhance cell proliferation and neuroblast differentiation, particularly maturation and complexity of neuroblast dendrites, in the DG via decreasing lipid peroxidation and increasing SOD2 level.

Predictive factors of symptomatic cerebral hyperperfusion after superficial temporal artery-middle cerebral artery anastomosis in adult patients with moyamoya disease

BACKGROUND

Symptomatic cerebral hyperperfusion (SCH) is a potential complication after superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis in patients with moyamoya disease. This retrospective study was designed to determine factors associated with SCH after STA-MCA anastomosis in adult moyamoya patients.

METHODS

Eighty-two adult moyamoya patients undergoing STA-MCA anastomosis between July 2005 and December 2010 were enrolled. Laboratory data such as haemoglobin and white blood cell (WBC) count, preoperative (patient characteristic data, initial clinical manifestation, the angiographic staging), intraoperative (surgical time, the operative side, anaesthetic technique, fluid balance, arterial pressure, arterial partial pressure of carbon dioxide, the lowest haematocrit, and intraoperative transfusion), and postoperative (arterial pressure, Acute Physiology and Chronic Health Evaluation II score) data were collected and used as predictable factors for postoperative SCH, in which a focal intense increase in cerebral blood flow at the anastomosis site was shown in postoperative single-photon emission computed tomography.

RESULTS

Among 82 patients with 99 surgeries, 39 patients (47 sides, 47%) suffered from transient neurological deterioration due to SCH from 1 to 9 days after operation (median: 2 days), which was sustained for 1-14 days (median: 7 days). The operation on the dominant hemisphere [odds ratio (OR), 5.09; 95% confidence interval (CI), 2.07-12.54, P<0.001] was an independent risk factor for SCH. Also, WBC count on postoperative day 1 was significantly correlated with SCH (OR 1.19; 95%CI, 1.02-1.38, P=0.029).

CONCLUSIONS

The operation on the dominant hemisphere and increased postoperative WBC count may be associated with SCH after STA-MCA anastomosis in adult-onset moyamoya patients.

Perfluorocarbon-facilitated CNS oxygen toxicity in rats: reversal by edaravone

Perfluorocarbon (PFC) has been hypothesized to potentially increase the risk of central nervous system oxygen toxicity (CNS-OT) under hyperbaric oxygen (HBO) conditions. However, little is known about the effects, mechanism and prevention of PFC-facilitated CNS-OT. A rat model of CNS-OT was used to evaluate the effects of intravenously-administered PFC emulsion. The electroencephalogram (EEG) was recorded during treatment with HBO(2) at 6.0 ATA in the presence and absence of PFC. Concentrations of malondialdehyde (MDA), nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) in the brain cortex and hippocampus were quantified. Changes in the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and NO synthase (NOS) in the brain cortex and hippocampus were also determined. Edaravone, a potent antioxidant, was used to prevent PFC-facilitated CNS-OT. The results showed that after PFC administration, the latency to first electrical discharge in EEG was significantly shortened; MDA, H(2)O(2), NO levels and NOS activity increased; and SOD, GPx and CAT activities decreased. Edaravone effectively protected against CNS-OT and the adverse effects of PFC. The results clearly demonstrate that PFC administered before HBO(2) would promote the occurrence of CNS-OT, and edaravone could serve as a promising chemoprophylactic agent to prevent CNS-OT.

Antioxidant strategies in neurocritical care

An increase in oxidative stress and overproduction of oxidizing reactive species plays an important role in the pathophysiology of several conditions encountered in the neurocritical care setting including: ischemic and hemorrhagic strokes, traumatic brain injury, acute respiratory distress syndrome, sepsis, and organ failure. The presence of oxidative stress in these conditions is supported by a large body of pre-clinical and clinical studies, and provides a rationale to support a potential therapeutic role for antioxidants. The purpose of this article is to briefly review the basic mechanisms and molecular biology of oxidative stress, summarize its role in critically ill neurological patients, and review available data regarding the potential role of antioxidant strategies in neurocritical care and future directions.

Acetylation of the pro-apoptotic factor, p53 in the hippocampus following cerebral ischemia and modulation by estrogen

BACKGROUND

Recent studies demonstrate that acetylation of the transcription factor, p53 on lysine(373) leads to its enhanced stabilization/activity and increased susceptibility of cells to stress. However, it is not known whether acetylation of p53 is altered in the hippocampus following global cerebral ischemia (GCI) or is regulated by the hormone, 17β-estradiol (17β-E(2)), and thus, this study examined these issues.

METHODOLOGY/PRINCIPAL FINDINGS

The study revealed that Acetyl p53-Lysine(373) levels were markedly increased in the hippocampal CA1 region after GCI at 3 h, 6 h and 24 h after reperfusion, an effect strongly attenuated by 17β-E(2). 17β-E(2) also enhanced interaction of p53 with the ubiquitin ligase, Mdm2, increased ubiquitination of p53, and induced its down-regulation, as well as attenuated elevation of the p53 transcriptional target, Puma. We also observed enhanced acetylation of p53 at a different lysine (Lys(382)) at 3 h after reperfusion, and 17β-E(2) also markedly attenuated this effect. Furthermore, administration of an inhibitor of CBP/p300 acetyltransferase, which acetylates p53, was strongly neuroprotective of the CA1 region following GCI. In long-term estrogen deprived (LTED) animals, the ability of 17β-E(2) to attenuate p53 acetylation was lost, and intriguingly, Acetyl p53-Lysine(373) levels were markedly elevated in sham (non-ischemic) LTED animals. Finally, intracerebroventricular injections of Gp91ds-Tat, a specific NADPH oxidase (NOX2) inhibitor, but not the scrambled tat peptide control (Sc-Tat), attenuated acetylation of p53 and reduced levels of Puma following GCI.

CONCLUSIONS/SIGNIFICANCE

The studies demonstrate that p53 undergoes enhanced acetylation in the hippocampal CA1 region following global cerebral ischemia, and that the neuroprotective agent, 17β-E(2), markedly attenuates the ischemia-induced p53 acetylation. Furthermore, following LTED, the suppressive effect of 17β-E(2) on p53 acetylation is lost, and p53 acetylation increases in the hippocampus, which may explain previous reports of increased sensitivity of the hippocampus to ischemic stress following LTED.

Increases of antioxidants are related to more delayed neuronal death in the hippocampal CA1 region of the young gerbil induced by transient cerebral ischemia

In age-related studies, young animals are resistant to ischemic damage. In present study, we investigated the neuronal death of pyramidal neurons and compared changes in the immunoreactivities and levels of antioxidants, Cu/Zn-SOD (SOD1), Mn-SOD (SOD2), catalase (CAT) and glutathione peroxidase (Gpx), in the hippocampal CA1 region between adult and young gerbils after 5 min of transient cerebral ischemia. In the adult ischemia-group, only a few (12%) of CA1 pyramidal neurons survived 4 days after ischemia-reperfusion (I-R); however, in the 4 days after I-R the young group, most of CA1 pyramidal neurons survived. Seven days after I-R, many (about 39%) of CA1 pyramidal neurons survived, thereafter, the neuronal death in the CA1 pyramidal neurons was not significantly changed. The immunoreactivities of all the antioxidants were well detected in CA1 pyramidal neurons in the adult sham-groups; in the young sham-groups, they were distinctively low compared to those in the adult sham-group. Four days after I-R in the adult group, all the immunoreactivities in the pyramidal neurons were dramatically deceased. However, at this time after I-R in the young groups, they were dramatically increased in the pyramidal neurons. From 7 days after I-R, all the immunoreactivities in the pyramidal neurons in the young ischemia-groups were distinctively decreased. In addition, the levels of all the antioxidants in the CA1 region of the young sham-groups were lower than those in the adult sham-group. Four days after I-R in the adult groups, the levels of all the antioxidants were dramatically deceased; however, at this time in the young ischemia-groups, they were distinctively increased in the CA1 region. Seven days after I-R, all the antioxidants levels in the CA1 region were distinctively decreased. In brief, we conclude that the increased antioxidants levels were related to a less and much delayed neuronal death in the CA1 pyramidal neurons in the young group following I-R injury.

Normobaric hyperoxia protects the blood brain barrier through inhibiting Nox2 containing NADPH oxidase in ischemic stroke

Normobaric hyperoxia (NBO) has been shown to be neuro- and vaso-protective during ischemic stroke. However, the underlying mechanisms remain to be fully elucidated. Activation of NADPH oxidase critically contributes to ischemic brain damage via increase in ROS production. We herein tested the hypothesis that NBO protects the blood-brain barrier (BBB) via inhibiting gp91^phox (or called Nox2) containing NADPH oxidase in a mouse model of middle cerebral artery occlusion (MCAO). Wild-type C57/BL6 mice and gp91^phoxknockout mice were given NBO (95% O₂) or normoxia (21% O₂) during 90-min MCAO, followed by 22.5 hrs of reperfusion. BBB damage was quantified by measuring Evans blue extravasation. The protein levels of matrix metalloproteinase-9 (MMP-9), tight junction protein occludin and gp91^phox were assessed with western blot. Gel zymography was used to assess the gelatinolytic activity of MMP-9. In the wild type mice, cerebral ischemia and reperfusion led to remarkable Evans blue extravasation, significantly increased gp91^phox and MMP-9 levels and decreased occludin levels in the ischemic brain tissue. In gp91^phox knockout mice, the changes in Evans blue extravasation, MMP-9 and occludin were at much smaller magnitudes when compared to the wild type. Importantly, NBO treatment significantly reduced the changes in all measured parameters in wild type mice, while did not cause additional reductions in these changes when gp91^phox was knocked out. These results indicate that activation of Nox2 containing NADPH oxidase is implicated in the induction of MMP-9, loss of occludin and BBB disruption in ischemic stroke, and inhibition of Nox2 may be an important mechanism underlying NBO-afforded BBB protection.

Pro-apoptotic activity of inhibitory PAS domain protein (IPAS), a negative regulator of HIF-1, through binding to pro-survival Bcl-2 family proteins

Inhibitory PAS (Per/Arnt/Sim) domain protein (IPAS) is a dominant negative transcription factor that represses hypoxia-inducible factor 1 (HIF-1) activity. In this study, we show that IPAS also functions as a pro-apoptotic protein through binding to pro-survival Bcl-2 family members. In a previous paper, we reported that NF-κB-dependent IPAS induction by cobalt chloride repressed the hypoxic response in PC12 cells. We found that prolonged incubation under the same conditions caused apoptosis in PC12 cells. Repression of IPAS induction protected cells from apoptosis. Furthermore, knockdown of IPAS recovered cell viability. EGFP-IPAS protein was localized in both the nucleus and the cytoplasm, with a large fraction associated with mitochondria. Mitochondrial IPAS induced mitochondria depolarization and caspase-3 activation. Immunoprecipitation assays revealed that IPAS is associated with Bcl-x(L), Bcl-w and Mcl-1. The association of IPAS with Bcl-x(L) was also observed in living cells by the FLIM-based FRET analysis, indicating direct binding between the two proteins. IPAS contributed to dysfunction of Bcl-x(L) by inhibiting the interaction of Bcl-x(L) with Bax. These results demonstrate that IPAS functions as a dual function protein involved in transcription repression and apoptosis.

Mechanisms of estrogens' dose-dependent neuroprotective and neurodamaging effects in experimental models of cerebral ischemia

Ever since the hypothesis was put forward that estrogens could protect against cerebral ischemia, numerous studies have investigated the mechanisms of their effects. Despite initial studies showing ameliorating effects, later trials in both humans and animals have yielded contrasting results regarding the fundamental issue of whether estrogens are neuroprotective or neurodamaging. Therefore, investigations of the possible mechanisms of estrogen actions in brain ischemia have been difficult to assess. A recently published systematic review from our laboratory indicates that the dichotomy in experimental rat studies may be caused by the use of insufficiently validated estrogen administration methods resulting in serum hormone concentrations far from those intended, and that physiological estrogen concentrations are neuroprotective while supraphysiological concentrations augment the damage from cerebral ischemia. This evidence offers a new perspective on the mechanisms of estrogens’ actions in cerebral ischemia, and also has a direct bearing on the hormone replacement therapy debate. Estrogens affect their target organs by several different pathways and receptors, and the mechanisms proposed for their effects on stroke probably prevail in different concentration ranges. In the current article, previously suggested neuroprotective and neurodamaging mechanisms are reviewed in a hormone concentration perspective in an effort to provide a mechanistic framework for the dose-dependent paradoxical effects of estrogens in stroke. It is concluded that five protective mechanisms, namely decreased apoptosis, growth factor regulation, vascular modulation, indirect antioxidant properties and decreased inflammation, and the proposed damaging mechanism of increased inflammation, are currently supported by experiments performed in optimal biological settings.

Methyleugenol reduces cerebral ischemic injury by suppression of oxidative injury and inflammation

The present study tested the cytoprotective effect of methyleugenol in an in vivo ischemia model (i.e. middle cerebral artery occlusion (MCAO) for 1.5 h and subsequent reperfusion for 24 h) and further investigated its mechanism of action in in vitro cerebral ischemic models. When applied shortly after reperfusion, methyleugenol largely reduced cerebral ischemic injury. Methyleugenol decreased the caspase-3 activation and death of cultured cerebral cortical neurons caused by oxygen-glucose deprivation (OGD) for 1 h and subsequent re-oxygenation for 24 h. Methyleugenol markedly reduced superoxide generation in the ischemic brain and decreased the intracellular oxidative stress caused by OGD/re-oxygenation. It was found that methyleugenol elevated the activities of superoxide dismutase and catalase. Further, methyleugenol inhibited the production of nitric oxide and decreased the protein expression of inducible nitric oxide synthase. Methyleugenol down-regulated the production of pro-inflammatory cytokines in the ischemic brain as well as in immunostimulated mixed glial cells. The results indicate that methyleugenol could be useful for the treatment of ischemia/inflammation-related diseases.

Antecedent ethanol attenuates cerebral ischemia/reperfusion-induced leukocyte-endothelial adhesive interactions and delayed neuronal death: role of large conductance, Ca2+-activated K+ channels

EtOH-PC reduces postischemic neuronal injury in response to cerebral (I/R). We examined the mechanism underlying this protective effect by determining (i) whether it was associated with a decrease in I/R-induced leukocyte-endothelial adhesive interactions in postcapillary venules, and (ii) whether the protective effects were mediated by activation of large conductance, calcium-activated potassium (BK(Ca)) channels. Mice were administered ethanol by gavage or treated with the BK(Ca) channel opener, NS1619, 24 hours prior to I/R with or without prior treatment with the BK(Ca) channel blocker, PX. Both CCA were occluded for 20 minutes followed by two and three hours of reperfusion, and rolling (LR) and adherent (LA) leukocytes were quantified in pial venules using intravital microscopy. The extent of DND, apoptosis and glial activation in hippocampus were assessed four days after I/R. Compared with sham, I/R elicited increases in LR and LA in pial venules and DND and apoptosis as well as glial activation in the hippocampus. These effects were attenuated by EtOH-PC or antecedent NS1619 administration, and this protection was reversed by prior treatment with PX. Our results support a role for BK(Ca) channel activation in the neuroprotective effects of EtOH-PC in cerebral I/R.

mGluR1 antagonist decreased NADPH oxidase activity and superoxide production after transient focal cerebral ischemia

NADPH oxidase, which is activated by PKC and signaling via the NMDA receptor, is one of the crucial enzymes for superoxide production in the CNS. We showed earlier that the metabotropic glutamate receptor 1 (mGluR1) plays an important role in the activation of PKC and tyrosine phosphorylation of the NMDA receptor, which has been implicated in enhancement of the channel activity, after cerebral ischemia. In this study, we sought to determine the role of mGluR1 in the activation of NADPH oxidase and subsequent superoxide production after transient focal cerebral ischemia. The amounts of NADPH oxidase subunits in the membrane fraction were increased after the start of reperfusion. These changes were accompanied by increased NADPH oxidase activity followed by superoxide production. The administration of an mGluR1 antagonist attenuated NADPH oxidase activity, which was coincident with inhibition of superoxide production. We further showed that the increase in the amount of PKCδ, but not of PKCζ, as well as the increase in those of NADPH oxidase subunits, was attenuated by the mGluR1 antagonist. These results suggest that mGluR1 may be linked to the increase in NADPH oxidase activity that is mediated by PKCδ and subsequent superoxide production after cerebral ischemia.

Reperfusion and neurovascular dysfunction in stroke: from basic mechanisms to potential strategies for neuroprotection

Effective stroke therapies require recanalization of occluded cerebral blood vessels. However, reperfusion can cause neurovascular injury, leading to cerebral edema, brain hemorrhage, and neuronal death by apoptosis/necrosis. These complications, which result from excess production of reactive oxygen species in mitochondria, significantly limit the benefits of stroke therapies. We have developed a focal stroke model using mice deficient in mitochondrial manganese-superoxide dismutase (SOD2-/+) to investigate neurovascular endothelial damage that occurs during reperfusion. Following focal stroke and reperfusion, SOD2-/+ mice had delayed blood-brain barrier breakdown, associated with activation of matrix metalloproteinase and high brain hemorrhage rates, whereas a decrease in apoptosis and hemorrhage was observed in SOD2 overexpressors. Thus, induction and activation of SOD2 is a novel strategy for neurovascular protection after ischemia/reperfusion. Our recent study identified the signal transducer and activator of transcription 3 (STAT3) as a transcription factor of the mouse SOD2 gene. During reperfusion, activation of STAT3 and its recruitment into the SOD2 gene were blocked, resulting in increased oxidative stress and neuronal apoptosis. In contrast, pharmacological activation of STAT3 induced SOD2 expression, which limits ischemic neuronal death. Our studies point to antioxidant-based neurovascular protective strategies as potential treatments to expand the therapeutic window of currently approved therapies.

8-O-acetyl shanzhiside methylester attenuates apoptosis and ameliorates mitochondrial energy metabolism in rat cortical neurons exposed to oxygen-glucose deprivation

8-O-acetyl shanzhiside methylester (ND01), an iridoid glucoside compound, was isolated from the leaves of Lamiophlomis rotata (Benth.) Kudo. The present study elucidated the effects of ND01 on the cultured rat cortical neuron injury induced by oxygen-glucose deprivation. The results showed that ND01 treatment obviously attenuated apoptosis and ameliorated mitochondrial energy metabolism in rat cortical neurons by increasing cell survival rate, mitochondrial respiratory enzyme activities, mitochondrial respiratory control ratio and adenosine triphosphate (ATP) content, and by attenuating lactate dehydrogenase (LDH) leakage, intracellular Ca(2+) level and caspase-3 activity in a concentration-dependent manner. These findings indicated that ND01 has potential against cerebral ischemic injury, and its protective effect on oxygen-glucose deprivation-induced injury might be due to the suppression of intracellular Ca(2+) elevation and caspase-3 activity, and improvement of mitochondrial energy metabolism.

The protective effect of early hypothermia on PTEN phosphorylation correlates with free radical inhibition in rat stroke

We recently showed that intraischemic moderate hypothermia (30 degrees C) reduces ischemic damage through the Akt pathway after permanent distal middle cerebral artery occlusion in rats. The only Akt pathway component preserved by hypothermia is phosphorylated phosphatase and tensin homolog deleted on chromosome 10 (p-PTEN), which suggests that p-PTEN may have a central role in neuroprotection. Reactive oxygen species (ROS) are critically involved in mediating ischemic damage after stroke by interacting with signaling molecules, including Akt, PTEN, and delta-protein kinase C (PKC). We investigated the protective mechanisms of moderate hypothermia on these signaling proteins after transient focal ischemia in rats. Early moderate hypothermia (3 h) was administered 15 mins before reperfusion, and delayed moderate hypothermia (3 h) was applied 15 mins after reperfusion. Our results indicate that early hypothermia reduced infarction, whereas delayed hypothermia did not. However, both early and delayed hypothermia maintained levels of Mn-SOD (superoxide dismutase) and phosphorylated Akt and blocked delta-PKC cleavage, suggesting that these factors may not be critical to the protection of hypothermia. Nevertheless, early hypothermia preserved p-PTEN levels after reperfusion, whereas delayed hypothermia did not. Furthermore, ROS inhibition maintained levels of p-PTEN after stroke. Together, these findings suggest that phosphorylation levels of PTEN are closely associated with the protective effect of early hypothermia against stroke.

delta-Opioid receptor activation attenuates oxidative injury in the ischemic rat brain

Background

We have recently shown that δ-opioid receptors (DORs) play an important role in neuroprotection from hypoxic injury via the regulation of extracellular signaling-regulated kinase (ERK) and cytochrome c release. Since ERK and cytochrome c are differentially involved in caspase signaling of oxidative injury that significantly contributes to neuronal damage in ischemia/reperfusion, we considered if DOR activation protects the ischemic brain by attenuating oxidative injury.

Results

We observed that, in a model of cerebral ischemia with middle cerebral artery occlusion, DOR activation increased the activity of major antioxidant enzymes, glutathione peroxidase and superoxide dismutase, and decreased malondialdehyde and nitric oxide levels in the cortex exposed to cerebral ischemia/reperfusion. In addition, DOR activation reduced caspase 3 expression, though it did not significantly affect the increase in interleukin (IL)1β and tumor necrosis factor (TNF)α expression at the same timepoint. PD98059, an inhibitor of mitogen-activated protein kinase (MAPK) extracellular signaling-regulated kinase kinase, accelerated animal death during ischemia/reperfusion.

Conclusion

DOR activation attenuates oxidative injury in the brain exposed to ischemia/reperfusion by enhancing antioxidant ability and inhibiting caspase activity, which provides novel insights into the mechanism of DOR neuroprotection.

Water extract of samultang reduces apoptotic cell death by h(2)o(2)-induced oxidative injury in sk-N-mc cells

The purpose of this study was to evaluate the effects of the water extract of Samultang (SMT), a Chinese herb, on apoptotic cell death by H(2)O(2)-induced oxidative stress in SK-N-MC cells. A nuclear fragmentation was observed via fluorescence imaging 12 h after exposure to 30 microM H(2)O(2) and DNA laddering was detected via agarose electrophoresis gel. In addition, increases in sub-G1 phase and cleavage of the PARP protein were observed. However, treatment with SMT for 2 h prior to H(2)O(2) exposure significantly reduced apoptotic cell death induced by incubation with 30 microM H(2)O(2) in SK-N-MC cells. Pre-incubation with water extract of SMT for 2 h prevented the H(2)O(2)-induced decrease in mitochondrial transmembrane potential. SMT also attenuated the increase in caspase-3 activity and the breakdown of PARP protein caused by H(2)O(2)-induced oxidative stress. These results suggest that the water extract of SMT provides inhibition of apoptotic cell death against oxidative injury in SK-N-MC cells.

Neuroprotective effects of glycyrrhizic acid and 18beta-glycyrrhetinic acid in PC12 cells via modulation of the PI3K/Akt pathway

Glycyrrhizic acid (GA) and 18beta-glycyrrhetinic acid (18betaGA) are the bioactive compounds of licorice. The neuroprotective effects of GA and 18betaGA against serum/glucose deprivation and 6-hydroxydopamine (6-OHDA)-induced cytotoxicity in PC12 cells were investigated. The intracellular reactive oxygen species (ROS) content, the activity of the antioxidant enzymes of glutathione peroxidase (GPx) and catalase, the mitochondrial membrane potential (MMP), and the mitochondrial Bax/Bcl-2 ratio were determined. PI3K/Akt pathway signaling was also evaluated to study the possible protective mechanism. The results showed that GA treatment decreased the ROS content by elevating the activities of GPx and catalase, leading to a decreased MMP. GA and 18betaGA also lowered the mitochondrial Bax/Bcl-2 ratio and activated PI3K/Akt signal. The results suggest that GA may protect PC12 cells from ischemic injury via modulation of the intracellular antioxidant system and mitochondria-induced apoptosis. Moreover, GA and 18betaGA may modulate the ratio of the mitochondrial Bcl-2 family and influence PI3K/Akt signaling. These results demonstrate the neuroprotective ability of GA and 18betaGA and suggest that the cytotoxicity of 6-OHDA may influence the mitochondrial Bax/Bcl-2 ratio without altering the expression of Bax. This study also suggests a possible compound for treating neural disease and general neuronal health.

Brain oxidative stress as basic target of antioxidant traditional oriental medicines

Prevention and amelioration of Mibyou (sub-healthy condition) is the critical target for disease prevention including age-related diseases and cancer although the Mibyou condition is not yet pathologically defined. Since the oxidative stress is an underlying basic etiology associated with many diseases and aging, the psychologically induced oxidative stress, especially in the brain was supposed as one of the pathology of Mibyou. Several traditional herbal prescriptions applied for the brain disorder were found effective to prevent cerebral oxidative stress induced by ischemia/reperfusion and also under psychological distress produced by whiskers cut in mice. Shengmai San comprising three herbs, Panax ginseng, Ophiopogon japonicus and Schisandra chinensis is a traditional herbal medicine formula having a long history of using as a remedy and clinical prescription to treat coronal heart diseases. Multifunctional aspect of traditional herbal prescription was discussed in terms of preventing oxidative injury in the brain using Shengmai San as a typical prescription.

Protection of capsaicin against hypoxia–reoxygenation-induced apoptosis of rat hippocampal neurons

The aim of this study was to investigate the effect of capsaicin on hypoxia–reoxygenation (H/R)-induced apoptosis in primary rat hippocampal neurons. Three hours of hypoxia (1% O2) and subsequent reoxygenation for 24 h significantly increased the apoptotic death of hippocampal neurons, as evidenced by increases in both TUNEL-positive cell number and caspase-3 activity. Pretreatment with capsaicin (3–30 µmol/L) or the caspase-3-specific inhibitor acetyl-DEVD-CHO (100 µmol/L) markedly attenuated H/R-induced apoptosis in hippocampal neurons. Capsaicin also markedly induced the phosphorylation of Akt. The phosphoinositide 3-kinase (PI3K) inhibitor LY294002 (10 µmol/L) prevented any capsaicin-induced survival effect in hippocampal neurons. Intracellular levels of reactive oxygen species (ROS), which were greatly increased after H/R, were significantly inhibited by capsaicin, pyrrolidine dithiocarbamate (PDTC) (50 µmol/L), and LY294002. Taken together, these data suggest that capsaicin protects against H/R-induced apoptosis of hippocampal neurons via the PI3K/Akt-mediated signaling pathway, which is related to the inhibition of oxidative stress and caspase-3 activation.

Efficacy of superficial temporal artery-middle cerebral artery anastomosis with routine postoperative cerebral blood flow measurement during the acute stage in childhood moyamoya disease

OBJECT

Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving cerebral blood flow (CBF). It is undetermined, however, how rapid increase in CBF affects chronic ischemic brain during the acute stage in childhood moyamoya disease.

MATERIALS AND METHODS

The present study includes nine consecutive cases of patients with childhood moyamoya disease (2 to approximately 8 years old, 6.2 in average), who underwent superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis on 17 hemispheres. We prospectively performed single-photon emission computed tomography 1 and 7 days after 17 surgeries. The follow-up period ranged from 12 to 37 months (24.9 in average).

RESULTS

The outcome of 17 surgeries was excellent (disappearance of transient ischemic attack) in 14 hemispheres (82.4%) and good (reduction of transient ischemic attack) in three hemispheres (17.6%). No patient suffered peri-operative infarction, except for one (5.9%) manifesting as pseudolaminar necrosis in a part of the cerebral cortex supplied by STA-MCA bypass at the subacute stage, which did not affect his long-term neurological status. One patient (5.9%) presented with transient facial palsy due to hyperperfusion, which resolved within several days. No patient manifested permanent neurological deterioration during the follow-up period.

CONCLUSION

The STA-MCA anastomosis is a safe and effective treatment for childhood moyamoya disease. We recommend routine CBF measurement for avoiding surgical complications including both cerebral ischemia and hyperperfusion.