Sevoflurane postconditioning attenuates cerebral ischemia‐reperfusion injury via protein kinase B/nuclear factor‐erythroid 2‐related factor 2 pathway activation

Sevoflurane preconditioning promotes mesenchymal stem cells to relieve myocardial ischemia/reperfusion injury via TRPC6-induced angiogenesis

Background

Ischemic heart diseases is one of the leading causes of death worldwide. Although revascularization timely is an effective therapeutic intervention to salvage the ischemic myocardium, reperfusion itself causes additional myocardial injury called ischemia/reperfusion (I/R) injury. Bone marrow-derived mesenchymal stem cells (MSCs) is one of the promising cells to alleviate ischemic myocardial injury. However, this cell therapy is limited by poor MSCs survival after transplantation. Here, we investigated whether sevoflurane preconditioning could promote MSCs to attenuate myocardial I/R injury via transient receptor potential canonical channel 6 (TRPC6)-induced angiogenesis.

Methods

The anti-apoptotic effect of sevoflurane preconditioning on MSCs was determined by Annexin V-FITC/propidium iodide staining. TRPC6, hypoxia-inducible factor-1α (HIF-1α), Chemokine receptor 4 (CXCR4) and vascular endothelial growth factor (VEGF) protein expressions and VEGF release from MSCs were determined after hypoxia and reoxygenation (H/R). Small interfering RNA (siRNA) was used to knock down TRPC6 gene expression in MSCs. The angiogenesis of human umbilical vein endothelial cells (HUVECs) co-cultured with MSCs was determined by Matrigel tube formation. Myocardial I/R mouse model was induced by occluding left anterior descending coronary artery for 30 min and then reperfusion. MSCs or sevoflurane preconditioned MSCs were injected around the ligature border zone 5 min before reperfusion. Left ventricle systolic function, infarction size, serum LDH, cTnI and inflammatory cytokines were determined after reperfusion.

Results

Sevoflurane preconditioning up-regulated TRPC6, HIF-1α, CXCR4 and VEGF expressions in MSCs and VEGF release from MSCs under H/R, which were reversed by knockdown of TRPC6 gene using siRNA in MSCs. Furthermore, sevoflurane preconditioning promoted the angiogenic and anti-inflammatory effect of HUVECs co-cultured with MSCs. Sevoflurane preconditioned MSCs improved left ventricle systolic function and alleviated myocardial infarction and inflammation in mice subjected to I/R insult.

Conclusion

The current findings reveal that sevoflurane preconditioned MSCs boost angiogenesis in HUVECs subjected to H/R insult and attenuate myocardial I/R injury, which may be mediated by TRPC6 up-regulated HIF-1α, CXCR4 and VEGF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02649-3.

Phosphoinositide-3-Kinase/Akt-Endothelial Nitric Oxide Synthase Signaling Pathway Mediates the Neuroprotective Effect of Sevoflurane Postconditioning in a Rat Model of Hemorrhagic Shock and Resuscitation

BACKGROUND

Although extensive reports have demonstrated the neuroprotection of sevoflurane postconditioning in cases of focal and global cerebral ischemia/reperfusion, the underlying mechanisms are not completely elucidated. This study investigated whether this effect is related to endothelial nitric oxide synthase (eNOS) and mediated by the phosphoinositide-3-kinase pathway in a rat model of hemorrhagic shock and resuscitation.

METHODS

Adult male Sprague Dawley rats were subjected to hemorrhagic shock for 60 minutes and then resuscitation for 30 minutes in experimental groups. Sevoflurane postconditioning was performed at the beginning of resuscitation to completion. At 24 hours after resuscitation, the brain infarct volume was evaluated by 2,3,5-triphenyltetrazolium chloride staining. The neuronal morphological changes and apoptosis were determined by hematoxylin and eosin staining and immunohistochemistry analysis, respectively. The activity of phosphorylated Akt and eNOS was evaluated by Western blot analysis.

RESULTS

Brain injuries such as the cerebral infarct volume and pathological neuronal changes as well as cell apoptosis were observed in the hippocampus after hemorrhagic shock and resuscitation. Postconditioning with 2.4% sevoflurane significantly attenuated brain injuries. Wortmannin prevented the improvements of neuronal characteristics elicited by sevoflurane postconditioning as well as the hyperactivity of eNOS and phosphorylated Akt.

CONCLUSIONS

Sevoflurane postconditioning could attenuate brain injury induced by hemorrhagic shock and resuscitation, and this neuroprotective effect may be partly by upregulation of eNOS through the phosphoinositide-3-kinase/Akt signaling pathway.

The Nrf2 Pathway in Ischemic Stroke: A Review

Ischemic stroke, characterized by the sudden loss of blood flow in specific area(s) of the brain, is the leading cause of permanent disability and is among the leading causes of death worldwide. The only approved pharmacological treatment for acute ischemic stroke (intravenous thrombolysis with recombinant tissue plasminogen activator) has significant clinical limitations and does not consider the complex set of events taking place after the onset of ischemic stroke (ischemic cascade), which is characterized by significant pro-oxidative events. The transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of a great number of antioxidant and/or defense proteins, has been pointed as a potential pharmacological target involved in the mitigation of deleterious oxidative events taking place at the ischemic cascade. This review summarizes studies concerning the protective role of Nrf2 in experimental models of ischemic stroke, emphasizing molecular events resulting from ischemic stroke that are, in parallel, modulated by Nrf2. Considering the acute nature of ischemic stroke, we discuss the challenges in using a putative pharmacological strategy (Nrf2 activator) that relies upon transcription, translation and metabolically active cells in treating ischemic stroke patients.

Post-Treatment Sevoflurane Protects Against Hypoxic-Ischemic Brain Injury in Neonatal Rats by Downregulating Histone Methyltransferase G9a and Upregulating Nuclear Factor Erythroid 2-Related Factor 2 (NRF2)

BACKGROUND Perinatal hypoxia and subsequent reduction of cerebral blood flow leads to neonatal hypoxic-ischemic brain injury (HIBI), resulting in severe disability and even death. Preconditioning or post-conditioning with sevoflurane protects against cerebral injury. This study investigated the mechanism of sevoflurane in HIBI. MATERIAL AND METHODS The HIBI model of neonatal rats was established and the model rats were post-treated with sevoflurane. The oxygen-glucose deprivation (OGD) cell model was established, and the OGD cells were transfected with NRF2-siRNA plasmid and post-treated with sevoflurane. The Morris water maze test was used to detect the motor activity, spatial learning, and memory ability of HIBI rats. Histological stainings were performed to observe the area of cerebral infarction, record the number of neurons in the hippocampus, and assess neuron apoptosis. The levels of inflammatory factors were detected by ELISA. The protein levels of histone methyltransferase G9a and histone H3 lysine 9 (H3K9me2) were detected by western blot assay. The apoptosis was detected by flow cytometry. RESULTS Sevoflurane post-treatment significantly shortened the escape latency of HIBI neonatal rats, increased the density of neurons, reduced the area of cerebral infarction, and decreased the levels of inflammatory factors and neuronal apoptosis. Sevoflurane post-treatment decreased G9a and H3K9me2 levels, and G9a level was negatively correlated with NRF2 level. NRF2 silencing reversed the alleviation of sevoflurane post-treatment on OGD-induced cell injury. CONCLUSIONS Sevoflurane post-treatment promotes NRF2 expression by inhibiting G9a and H3K9me2, thus alleviating HIBI in neonatal rats.

Mechanism underlying sevoflurane-induced protection in cerebral ischemia–reperfusion injury

Cerebral ischemia is an extremely complex disease that can be caused by a variety of factors. Cerebral ischemia can cause great harm to human body. Sevoflurane is a volatile anesthetic that is frequently used in clinic, and has a lot of advantages, such as quick induction of general anesthesia, quick anesthesia recovery, no respiratory tract irritation, muscle relaxation, and small cycle effect. The mechanism of sevoflurane preconditioning or post-treatment induction is poorly understood. The purpose of this study was to illustrate the mechanism underlying sevoflurane-induced protection in cerebral ischemia–reperfusion injury and also provide theoretical guidance for future research.

Targeting autophagy to modulate hepatic ischemia/reperfusion injury: A comparative study between octreotide and melatonin as autophagy modulators through AMPK/PI3K/AKT/mTOR/ULK1 and Keap1/Nrf2 signaling pathways in rats

Hepatic ischemia-reperfusion (HIR) injury is a common pathophysiological process in many clinical settings. This study was designed to compare the protective role of octreotide (somatostatin analogue, OCT) and melatonin (N-acetyl-5-methoxytryptamine, MLT) through the modulation of autophagy against HIR injury in rats. Male albino rats were divided into sham, HIR, OCT at three doses (50, 75, and 100 μg/kg), MLT, MLT + OCT75, compound C (AMPK inhibitor, CC), and CC + OCT75 groups. Ischemia was induced for 30 min followed by 24 h reperfusion. Biochemical, histopathological, immunohistochemical, lipid peroxidation, ELISA, qPCR, and western blot techniques were performed in our study. Liver autophagy was restored by OCT at doses (50 or 75 μg/kg) as indicated by elevating the expressions of Beclin-1, ATG7, and LC3 accompanied by the reduction of p62 expression through induction of AMPK/S317-ULK1 and inhibition of PI3K/AKT/mTOR/S757-ULK1 signaling pathways. As well, OCT maintained the integrity of the Keap1-Nrf2 system for the normal hepatic functions via controlling the Keap1 turnover through autophagy in a p62-dependent manner, resulting in upholding a series of anti-oxidant and anti-inflammatory cascades. These effects were abolished by compound C. On the other hand, MLT showed a decrease in the autophagy markers via inhibiting AMPK/pS317-ULK1 and activating PI3K/AKT/mTOR/pS757-ULK1 pathways. Autophagy inhibition with MLT markedly reversed the hepatoprotective effects of OCT75 after HIR injury. Finally, our results proved for the first time that OCT75 was more effective than MLT as it was sufficient to induce protective autophagy in our HIR model, which led to the induction of Nrf2-dependent AMPK/autophagy pathways.

Protective effects of sevoflurane in cerebral ischemia reperfusion injury: a narrative review

Ischemia/reperfusion (I/R) injury is a phenomenon that the reperfusion of ischemic organs or tissues aggravates their damage, which poses a serious health threat and economic burden to the world. I/R gives rise to a series of physiological and pathological world, including inflammatory response, oxidative stress, brain edema, blood-brain barrier destruction, and neuronal death. Therefore, finding effective treatment measures is extremely important to the recovery of I/R patients and the improvement of long-term quality of life. Sevoflurane is an important volatile anesthetic which has been reported to reduce myocardial I/R damage and infarct size. Sevoflurane also has anti-inflammatory and neuroprotective effects. As reported sevoflurane treatment could reduce nerve function injury, cerebral infarction volume and the level of inflammatory factors. At the same time, there is evidence that sevoflurane can reduce neuron apoptosis and antioxidant stress. The protective effect of sevoflurane in brain injury has been proved to be existed in several aspects, so that a comprehensive understanding of its neuroprotective effect is helpful to exploit new treatment paths for I/R, provide clinicians with new clinical treatment decisions, contribute to the effective treatment of I/R patients and the improvement of quality of life after I/R healing.

Critical Role of Nrf2 in Experimental Ischemic Stroke

Ischemic stroke is one of the leading causes of death and long-term disability worldwide; however, effective clinical approaches are still limited. The transcriptional factor Nrf2 is a master regulator in cellular and organismal defense against endogenous and exogenous stressors by coordinating basal and stress-inducible activation of multiple cytoprotective genes. The Nrf2 network not only tightly controls redox homeostasis but also regulates multiple intermediary metabolic processes. Therefore, targeting Nrf2 has emerged as an attractive therapeutic strategy for the prevention and treatment of CNS diseases including stroke. Here, the current understanding of the Nrf2 regulatory network is critically examined to present evidence for the contribution of Nrf2 pathway in rodent ischemic stroke models. This review outlines the literature for Nrf2 studies in preclinical stroke and focuses on the in vivo evidence for the role of Nrf2 in primary and secondary brain injuries. The dynamic change and functional importance of Nrf2 signaling, as well as Nrf2 targeted intervention, are revealed in permanent, transient, and global cerebral ischemia models. In addition, key considerations, pitfalls, and future potentials for Nrf2 studies in preclinical stroke investigation are discussed.

Uric Acid Protects against Focal Cerebral Ischemia/Reperfusion-Induced Oxidative Stress via Activating Nrf2 and Regulating Neurotrophic Factor Expression

The aim of this study was to investigate whether uric acid (UA) might exert neuroprotection via activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway and regulating neurotrophic factors in the cerebral cortices after transient focal cerebral ischemia/reperfusion (FCI/R) in rats. UA was intravenously injected through the tail vein (16 mg/kg) 30 min after the onset of reperfusion in rats subjected to middle cerebral artery occlusion for 2 h. Neurological deficit score was performed to analyze neurological function at 24 h after reperfusion. Terminal deoxynucleotidyl transferase-mediated dNTP nick end labeling (TUNEL) staining and hematoxylin and eosin (HE) staining were used to detect histological injury of the cerebral cortex. Malondialdehyde (MDA), the carbonyl groups, and 8-hydroxyl-2′-deoxyguanosine (8-OHdG) levels were employed to evaluate oxidative stress. Nrf2 and its downstream antioxidant protein, heme oxygenase- (HO-) 1,were detected by western blot. Nrf2 DNA-binding activity was observed using an ELISA-based measurement. Expressions of BDNF and NGF were analyzed by immunohistochemistry. Our results showed that UA treatment significantly suppressed FCI/R-induced oxidative stress, accompanied by attenuating neuronal damage, which subsequently decreased the infarct volume and neurological deficit. Further, the treatment of UA activated Nrf2 signaling pathway and upregulated BDNF and NGF expression levels. Interestingly, the aforementioned effects of UA were markedly inhibited by administration of brusatol, an inhibitor of Nrf2. Taken together, the antioxidant and neuroprotective effects afforded by UA treatment involved the modulation of Nrf2-mediated oxidative stress and regulation of BDNF and NGF expression levels. Thus, UA treatment could be of interest to prevent FCI/R injury.

The effect of pre- and after-treatment of sevoflurane on central ischemia tolerance and the underlying mechanisms

In recent years, with continuous research efforts targeted at studying the effects of pre- and after-treatment of inhaled anesthetics, significant progress has been made regarding the common clinical use of low concentrations of inhaled sevoflurane and its effect on induced central ischemia tolerance by pre- and post-treatment. In this study, we collected, analyzed, classified, and summarized recent literature regarding the effect of sevoflurane on central ischemia tolerance and its related mechanisms. In addition, we provide a theoretical basis for the clinical application of sevoflurane to protect the central nervous system and other important organs against ischemic injury.

Sevoflurane postconditioning attenuates reactive astrogliosis and glial scar formation after ischemia-reperfusion brain injury

Cerebral ischemia leads to astrocyte's activation and glial scar formation. Glial scar can inhibit axonal regeneration during the recovery phase. It has demonstrated that sevoflurane has neuroprotective effects against ischemic stroke, but its effects on ischemia-induced formation of astrogliosis and glial scar are unknown. This study was designed to investigate the effect of sevoflurane postconditioning on astrogliosis and glial scar formation in ischemic stroke model both in vivo and in vitro. The results showed that 2.5% of sevoflurane postconditioning could significantly reduce infarction volume and improve neurologic deficits. And it could also decrease the expression of the glial scar marker glial fibrillary acidic protein (GFAP), neurocan and phosphacan in the peri-infarct region and markedly reduce the thickness of glial scar after ischemia/reperfusion (I/R). Consistent with the in vivo data, in the oxygen and glucose deprivation/reoxygenation (OGD/Re) model, sevoflurane postconditioning could protect astrocyte against OGD/Re-induced injury, decrease the expression of GFAP, neurocan and phosphacan. Further studies demonstrated that sevoflurane postconditioning could down-regulate the expression of Lamp1 and active cathepsin B, and block I/R or OGD/Re-induced release of cathepsin B from the lysosomes into cytoplasm. In order to confirm whether inhibition of cathepsin B could attenuate the formation of glial scar, we used cathepsin B inhibitor CA-074Me as a positive control. The results showed that inhibition of cathepsin B could decrease the expression of GFAP, neurocan and phosphacan. Taken together, sevoflurane postconditioning can attenuate astrogliosis and glial scar formation after ischemic stroke, associating with inhibition of the activation and release of lysosomal cathepsin B.

Anti-oxidative aspect of inhaled anesthetic gases against acute brain injury

Acute brain injury is a critical and emergent condition in clinical settings, which needs to be addressed urgently. Commonly acute brain injuries include traumatic brain injury, ischemic and hemorrhagic strokes. Oxidative stress is a key contributor to the subsequent injuries and impedes the reparative process after acute brain injury; therefore, facilitating an anti-oxidative approach is important in the care of those diseases. Readiness to deliver and permeability to blood brain barrier are essential for the use of this purpose. Inhaled anesthetic gases are a group of such agents. In this article, we discuss the anti-oxidative roles of anesthetic gases against acute brain injury.

SMND-309 promotes neuron survival through the activation of the PI3K/Akt/CREB-signalling pathway

Context In clinical practice, the promotion of neuron survival is necessary to recover neurological functions after the onset of stroke. Objective This study aimed to investigate the post-ischaemic neuroprotective effect of SMND-309, a novel metabolite of salvianolic acid, on differentiated SH-SY5Y cells. Materials and methods SH-SY5Y cells were differentiated by pre-treating with 5 μM all-trans-retinoic acid for 6 d. The differentiated SH-SY5Y cells were exposed to oxygen-glucose deprivation (OGD) for 2 h and reperfusion (R) for 24 h to induce OGD/R injury. After OGD injury, differentiated SH-SY5Y cells were treated with or without SMND-309 (5, 10, 20 μM) for another 24 h. Cell viability was detected through Cell counting kit-8 assay and lactate dehydrogenase leakage assay. Apoptosis was evaluated through flow cytometry, caspase-3 activity assay. Changes in protein levels were assessed through Western blot. Results SMND-309 ameliorated the degree of injury in the differentiated SH-SY5Y cells by increasing cell viabilities (5 μM, 65.4% ± 4.1%; 10 μM, 69.8% ± 3.7%; 20 μM, 75.3% ± 5.1%) and by reducing LDH activity (20 μM, 2.5 fold) upon OGD/R stimulation. Annexin V-fluorescein isothiocyanate/propidium iodide staining results suggested that apoptotic rate of differentiated SH-SY5Y cells decreased from 43.8% induced by OGD/R injury to 19.2% when the cells were treated with 20 μM SMND-309. SMND-309 significantly increased the Bcl-2 level of the injured differentiated SH-SY5Y cells but decreased the caspase-3 activity of these cells by 1.6-fold. In contrast, SMND-309 did not affect the Bax level of these cells. SMND-309 evidently increased the protein expression of BDNF when Akt and CREB were activated. This function was antagonized by the addition of LY294002. Conclusion SMND-309 can prevent neuronal cell death in vitro. This process may be related to the activation of the PI3K/Akt/CREB-signalling pathway.

Sevoflurane prevents stroke-induced depressive and anxiety behaviors by promoting cannabinoid receptor subtype I-dependent interaction between β-arrestin 2 and extracellular signal-regulated kinases 1/2 in the rat hippocampus

One of the most frequent psychological consequences of stroke is depression. Previous animal studies have demonstrated that post-conditioning with sevoflurane protects against focal cerebral ischemia and reperfusion injury. Thus, we hypothesized that repeated exposure to sevoflurane after transient ischemia can prevent the development of depressive-like behavior. To test this hypothesis, we induced transient cerebral ischemia via transient occlusion of bilateral common carotid arteries and examined the effects of subsequent repeated exposure to sevoflurane on sucrose preference, locomotor activity, and rearing activity in rats. To explore the putative neurobiological mechanisms, we further investigated the roles of hippocampal CB1 receptor in the behavioral effects of sevoflurane. We found that repeated sevoflurane exposures reversed ischemia-induced depressive-like behaviors. Furthermore, CB1 receptor inhibition in the dorsal hippocampus (DH) abolished the effects of sevoflurane exposures on ischemia-induced depressive-like behaviors. In addition, repeated sevoflurane exposures increased CB1 receptor expression and endocannabinoids levels in the DH of ischemic rats. Moreover, repeated sevoflurane exposures enhanced the expression of β-arrestin 2, increased the activation of extracellular signal-regulated kinases (ERK)1/2, and promoted the interaction of β-arrestin 2 and ERK1/2 in the DH, and such effects were reversed by CB1 receptor antagonism in the DH. Finally, β-arrestin 2 expression and ERK1/2 activation in the DH were critical for the preventative effects of sevoflurane exposures on ischemia-induced depressive-like behaviors. Taken together, our results suggested that sevoflurane exposure after brain ischemia may prevent the development of depression, and such preventative effects of sevoflurane are likely ascribed to the activation of CB1 receptor-mediated β-arrestin 2-ERK1/2 signaling pathways. We propose that the following mechanisms are critical for the preventative effects of sevoflurane against post-stroke depressive and anxiety behaviors: repeated sevoflurane exposure after transient brain ischemia enhances N-arachidonoylethanolamine (AEA) and 2-Arachidonoylglycerol (2-AG) levels and normalize cannabinoid receptor type 1 (CB1) receptor expression in the dorsal hippocampus, which results in enhanced interaction of β-arrestin 2 and extracellular signal-regulated kinases (ERK1/2) and increased ERK1/2 activation, leading to decreased depressive and anxiety behaviors. We think these findings should provide a new strategy for treatment of post-stroke depression.

Nrf2 Weaves an Elaborate Network of Neuroprotection Against Stroke

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a neuroprotective transcription factor that has recently attracted increased attention. Stroke, a common and serious neurological disease, is currently a leading cause of death in the USA so far. It is therefore of vital importance to explore how Nrf2 behaves in stroke. In this review, we first introduce the structural features of Nrf2 and Kelch-like ECH-associated protein 1 (Keap1) and briefly depict the activation, inactivation, and regulation processes of the Nrf2 pathway. Next, we discuss the physiopathological mechanisms, upstream modulators, and downstream targets of the Nrf2 pathway. Following this background, we expand our discussion to the roles of Nrf2 in ischemic and hemorrhagic stroke and provide several potential future directions. The information presented here may be useful in the design of future experimental research and increase the likelihood of using Nrf2 as a therapeutic target for stroke in the future.

Pre-treatment with metformin activates Nrf2 antioxidant pathways and inhibits inflammatory responses through induction of AMPK after transient global cerebral ischemia

Global cerebral ischemia arises in patients who have a variety of clinical conditions including cardiac arrest, shock and asphyxia. In spite of advances in understanding of the brain ischemia and stroke etiology, therapeutic approaches to improve ischemic injury still remain limited. It has been established that metformin can attenuate cell death in cerebral ischemia. One of the main functions of metformin is proposed to be conducted via AMP-activated protein kinase (AMPK)-dependent pathway in the experimental cerebral ischemia model. It is also established that metformin can suppress inflammation and activate Nuclear factor erythroid 2-related factor (Nrf2) pathways in neurons. In the current study, the role of metformin in regulating inflammatory and antioxidant pathways in the global cerebral ischemia was investigated. Our results indicated that pretreatment of rats by metformin attenuated cellular levels of nuclear factor-κB, Tumor Necrosis Factor alpha and Cyclooxygenase-2 which are considered as three important proteins involved in the inflammation pathway. Pretreatment by metformin increased the level of Nrf2 and heme oxygenase-1 in the hippocampus of ischemic rats compared with untreated ischemic group. Moreover, pretreatment by metformin enhanced the level of glutathione and catalase activities compared with them in ischemic group. Such protective changes detected by metformin pretreatment were reversed by injecting compound c, an AMPK inhibitor. These findings suggested that metformin might protect cells through modulating inflammatory and antioxidant pathways via induction of AMPK. However, more experimental and clinical trial studies regarding neuroprotective potential of metformin and the involved mechanisms, especially in the context of cerebral ischemic injuries, are necessary.