Sevoflurane Preconditioning Research Articles

Sevoflurane preconditioning ameliorates traumatic spinal cord injury through caveolin-3-dependent cyclooxygenase-2 inhibition.

Acute traumatic spinal cord injury (tSCI) results in a lifetime of paralysis associated with a host of medical complications. The developing secondary complications of tSCI may result in further chronic neurodegenerative diseases. Sevoflurane preconditioning (SF-PreCon) has shown guaranteed protective effects in myocardial or cerebral ischemic/reperfusion injury. However, the role of SF-PreCon in tSCI still remains to be elucidated. Here, we found that SF-PreCon ameliorated the developing secondary complications through reducing the apoptosis rate and the secretion of inflammatory cytokines in injured spinal cord tissues, and therefore enhancing the recovery after tSCI. Notably, we demonstrated that SF-PreCon ameliorates tSCI through inhibiting Cycloxygenase-2 (COX-2). Importantly, we verified that SF-PreCon inhibits the expression of COX-2 and reduces the apoptosis rate after tSCI via the induction of Caveolin-3 (Cav-3). Taken together, our results suggest that SF-PreCon ameliorates tSCI via Cav-3-dependent COX-2 inhibition and provide an economical and practical method against the secondary injury after tSCI.

Sevoflurane preconditioning protects from posttransplant injury in mouse lung transplantation

BackgroundAlthough sevoflurane (Sevo) had been shown to ameliorate posttransplant injury in various organs, data available are inconsistent, particularly in the context of lung transplantation (Tx). We here investigated if preconditioning by Sevo can protect from posttransplant injury regarding both, primary graft dysfunction (PGD) and acute rejection (AR) after experimental lung Tx, thereby focusing on two important clinical outcome parameters. Materials and methodsThree experimental approaches were used: (1) BALB/c mice were preconditioned for 2 h with Sevo or a fentanyl cocktail (Control; n = 10); (2) syngeneic (Syn) mouse lung Tx (C57BL/6) with a Sevo-preconditioned graft followed by 18 h storage to mimic PGD (Syn-Tx, n = 12) versus controls (fentanyl cocktail); and (3) allogeneic (Allo) Tx (BALB/c, donor; C57BL/6, recipient) to mimic AR (Allo-Tx, n = 12) versus controls (fentanyl cocktail). Syn-Tx grafts were harvested on Day 1, Allo-Tx grafts on Day 3 and analyzed for histology, immunohistochemistry, blood gas analysis, and inflammatory cytokines (enzyme-linked immunosorbent assay or reverse transcription polymerase chain reaction). ResultsEvaluating the preconditioning effect of Sevo only showed significantly better oxygenation (P = 0.03) and a tendency toward lower levels of lung tissue messenger RNA for tumor necrosis factor-α. In Syn-Tx recipients, the Sevo group had histologically a tendency toward an attenuation of PGD and showed significantly lower levels of interleukin 6 (P = 0.01) in plasma, but higher levels of interleukin 10 (P < 0.01) in lungs. Allo-Tx grafts in Sevo Tx recipients showed attenuated AR with histologically significantly lower rejection scores (P = 0.03), fewer classical macrophages (F4/80+; P < 0.01), but more anti-inflammatory activated macrophages (M2, CD206+; P < 0.01). Functionally, the Sevo group had a tendency toward improved oxygenation. ConclusionsWe demonstrated that Sevo preconditioning has protective effects on lung transplants in both, PGD and AR. The observed amelioration may be attributed to suppressed inflammatory cytokines during PGD and the induction of alternatively activated macrophages during AR. These promising data could set the base for using Sevo preconditioning in donor lungs for a human trial.

Kelch-like ECH-associated Protein 1-dependent Nuclear Factor-E2-related Factor 2 Activation in Relation to Antioxidation Induced by Sevoflurane Preconditioning.

The authors have reported that antioxidative effects play a crucial role in the volatile anesthetic-induced neuroprotection. Accumulated evidence shows that endogenous antioxidation could be up-regulated by nuclear factor-E2-related factor 2 through multiple pathways. However, whether nuclear factor-E2-related factor 2 activation is modulated by sevoflurane preconditioning and, if so, what is the signaling cascade underlying upstream of this activation are still unknown. Sevoflurane preconditioning in mice was performed with sevoflurane (2.5%) 1 h per day for five consecutive days. Focal cerebral ischemia/reperfusion injury was induced by middle cerebral artery occlusion. Expression of nuclear factor-E2-related factor 2, kelch-like ECH-associated protein 1, manganese superoxide dismutase, thioredoxin-1, and nicotinamide adenine dinucleotide phosphate quinolone oxidoreductase-1 was detected (n = 6). The antioxidant activities and oxidative product expression were also examined. To determine the role of kelch-like ECH-associated protein 1 inhibition-dependent nuclear factor-E2-related factor 2 activation in sevoflurane preconditioning-induced neuroprotection, the kelch-like ECH-associated protein 1-nuclear factor-E2-related factor 2 signal was modulated by nuclear factor-E2-related factor 2 knockout, kelch-like ECH-associated protein 1 overexpression lentivirus, and kelch-like ECH-associated protein 1 deficiency small interfering RNA (n = 8). The infarct volume, neurologic scores, and cellular apoptosis were assessed. Sevoflurane preconditioning elicited neuroprotection and increased nuclear factor-E2-related factor 2 nuclear translocation, which in turn up-regulated endogenous antioxidation and reduced oxidative injury. Sevoflurane preconditioning reduced kelch-like ECH-associated protein 1 expression. Nuclear factor-E2-related factor 2 ablation abolished neuroprotection and reversed sevoflurane preconditioning by mediating the up-regulation of antioxidants. Kelch-like ECH-associated protein 1 overexpression reversed nuclear factor-E2-related factor 2 up-regulation and abolished the neuroprotection induced by sevoflurane preconditioning. Kelch-like ECH-associated protein 1 small interfering RNA administration improved nuclear factor-E2-related factor 2 expression and the outcome of mice subjected to ischemia/reperfusion injury. Kelch-like ECH-associated protein 1 down-regulation-dependent nuclear factor-E2-related factor 2 activation underlies the ability of sevoflurane preconditioning to activate the endogenous antioxidant response, which elicits its neuroprotection.

Sevoflurane preconditioning induced endogenous neurogenesis against ischemic brain injury by promoting microglial activation.

Brain ischemia causes irreversible damage to functional neurons in cases of infarct. Promoting endogenous neurogenesis to replace necrotic neurons is a promising therapeutic strategy for ischemia patients. The neuroprotective role of sevoflurane preconditioning implies that it might also enhance endogenous neurogenesis and functional restoration in the infarct region. By using a transient middle cerebral artery occlusion (tMCAO) model, we discovered that endogenous neurogenesis was enhanced by sevoflurane preconditioning. This enhancement process is characterized by the promotion of neuroblast proliferation within the subventricular zone (SVZ), migration and differentiation into neurons, and the presence of astrocytes and oligodendrocytes at the site of infarct. The newborn neurons in the sevoflurane preconditioning group showed miniature excitatory postsynaptic currents (mEPSCs), increased synaptophysin and PSD95 staining density, indicating normal neuronal function. Furthermore, long-term behavioral improvement was observed in the sevoflurane preconditioning group consistent with endogenous neurogenesis. Further histological analyses showed that sevoflurane preconditioning accelerated microglial activation, including migration, phagocytosis and secretion of brain-derived neurotrophic factor (BDNF). Intraperitoneal injection of minocycline, a microglial inhibitor, suppressed microglial activation and reversed neurogenesis. Our data showed that sevoflurane preconditioning promoted microglial activities, created a favorable microenvironment for endogenous neurogenesis and accelerated functional reconstruction in the infarct region.

Sevoflurane pre-conditioning increases phosphorylation of Erk1/2 and HO-1 expression via inhibition of mPTP in primary rat cortical neurons exposed to OGD/R

BackgroundAs an indispensable clinical inhalation anesthetic, sevoflurane is widely used for peri-operative sedation. The neuroprotective effect of sevoflurane pre-conditioning against cerebral ischemia/reperfusion has been gradually realized, but the underlying mechanism during the early reperfusion period has not been established. MethodPrimary cultured cortical neurons were treated with 2% sevoflurane pre-conditioning for 30min, exposed to oxygen-glucose deprivation for 90min, and followed by 60min of reperfusion (OGD/R). Additionally, neuronal cells were treated with an inhibitor of extracellular signal–related kinases 1 and 2 (Erk1/2) phosphorylation (PD98059), a mPTP opener (atractyloside), or a mPTP opening inhibitor (cyclosporine A) before sevoflurane pre-conditioning. ResultSevoflurane pre-conditioning decreased neuronal apoptosis (assessed by TUNEL), oxidative stress (assessed by malondialdehyde [MDA], superoxide dismutase [SOD], and heme oxygenase [HO]-1), and opening of mitochondrial permeability transition pores [mPTPs] (assessed by calcein-cobalt), but increased neuronal viability (assessed by MTT) and mitochondrial membrane potential (assessed by JC-1) after OGD/R exposure compared with OGD/R treatment alone. Pre-treatment with the mPTP opener and inhibitor of Erk1/2 phosphorylation abolished the protective effect induced by sevoflurane pre-conditioning. Pre-treatment with the mPTP opener attenuated the phosphorylation of Erk1/2 in mitochondria of neuronal cultures exposed to OGD/R induced by sevoflurane pre-conditioning. The mPTP opening inhibitor, like sevoflurane pre-conditioning, increased phosphorylation of Erk1/2 after OGD/R exposure, while PD98059 failed to reverse inhibition of mPTP opening in cultures exposed to OGD/R induced by sevoflurane pre-conditioning. ConclusionThe neuroprotective mechanism of sevoflurane pre-conditioning might be associated with increased Erk1/2 phosphorylation in mitochondria via inhibition of mPTP opening in the early reperfusion period.

Sevoflurane preconditioning in on-pump coronary artery bypass grafting: a meta-analysis of randomized controlled trials.

Sevoflurane preconditioning (SevoPreC) has been proved to prevent organ ischemia/reperfusion (I/R) injury in various animal models and preclinical studies. Clinical trials on cardioprotection by SevoPreC for adult patients undergoing coronary artery bypass graft (CABG) revealed mixed results. The aim of this meta-analysis was to evaluate the cardiac effect of SevoPreC in on-pump CABG. Randomized controlled trials (RCT) comparing the cardiac effect of SevoPreC (compared with control) in adult patients undergoing CABG were searched from PubMed, Embase, and the Cochrane Library (up to November 2015). The primary endpoints were postoperative troponin levels. Additional endpoints were CK-MB levels, mechanic ventilation (MV) duration, intensive care unit (ICU) stay, and hospital length of stay (LOS). Six trials with eight comparisons enrolling a total of 384 study patients reporting postoperative troponin levels were identified. Compared with controls, SevoPreC decreased postoperative myocardial troponin levels [standardized mean difference (SMD)=-0.38; 95% CI, -0.74 to -0.03; P=0.04; I 2=63.9%]. However, no significant differences were observed in postoperative CK-MB levels [weighted mean difference (WMD)=-1.71; P=0.37; I 2=37.7%], MV duration (WMD=-0.53; P=0.47; I 2=0.0%), ICU stay (WMD=-0.91; P=0.39; I 2=0.9%), and hospital LOS (WMD=0.08; P=0.86; I 2=8.0%). Available evidence from the present systematic review and meta-analysis suggests that sevoflurane preconditioning may reduce troponin levels in on-pump CABG. Future high-quality, large-scale clinical trials should focus on the early and long-term clinical effect of SevoPreC in on-pump CABG.

Sevoflurane anesthetic preconditioning protects the lung endothelial glycocalyx from ischemia reperfusion injury in an experimental lung autotransplant model.

The glycocalyx is a glycoprotein-polysaccaride layer covering the endothelium luminal surface, and plays a key regulatory role in several endothelial functions. Lung ischemia reperfusion (IR) is a clinical entity that occurs in everyday thoracic surgery and causes glycocalix destruction and a florid local and systemic immune response. Moreover, sevoflurane is able to modulate the inflammatory response triggered by IR lung injury. In this study, we evaluated the protective effects of sevoflurane on the pulmonary endothelial glycocalyx in an in-vivo lung autotransplant model in pigs. Sixteen Large White pigs underwent pneumonectomy plus lung autotransplant. They were divided into two groups depending on the hypnotic agent received (propofol or anesthetic preconditioning with sevoflurane). Glycocalyx components (syndecan-1 and heparan sulphate), cathepsin B, chemokines (MCP-1, MIP-1, and MIP-2) and adhesion molecules (VCAM and ICAM-1) were measured at four different timepoints using porcine-specific enzyme-linked immunosorbent assay (ELISA) kits. There were no differences between groups in weight or in surgical and one-lung ventilation time. Greater glycocalyx destruction and higher chemokine and adhesion molecule expression were observed in the group that did not receive sevoflurane. Heparan sulphate and serum syndecan levels were higher in the propofol group (P<0.0001) after reperfusion, as was cathepsin B activity (P<0.015). MCP-1, MIP-1, MIP-2, VCAM, and ICAM-1 levels were also higher in the propofol group (P<0.006). Sevoflurane preconditioning protects pulmonary glycocalyx and reduces expression of leukocyte chemokines in an in-vivo model of pulmonary IR.

Molecular studies of the immunological effects of the sevoflurane preconditioning in the liver and lung in a rat model of liver ischemia/reperfusion injury

Sevoflurane has been shown to improve ischemia/reperfusion injury (IRI) through several mechanisms, including amelioration of inflammatory response. However, there haven't been any studies considering the potential role of the complement system in sevoflurane-mediated amelioration of ischemia/reperfusion injury. Our purpose was to investigate the molecular mechanisms involved in sevoflurane preconditioning in liver and lung injury induced by liver ischemia-reperfusion (LIR), giving emphasis to the immunological mechanisms. In order to do that, fifty male Wistar rats were randomly allocated in five groups (n=10 each): Animals in group LIR received ketamine and xylazine and were then subjected to ischemia of the right and median hepatic lobe for 45 min and reperfusion for 6h. Group SEVO/LIR received sevoflurane and then LIR was induced, as in group LIR. Animals in group SHAM/LIR were anesthetized with ketamine and xylazine and then laparotomy followed. Group SHAM/SEVO received sevoflurane for 30 min and then laparotomy followed. Finally, in group VEN, animals only received ketamine and xylazine. Our results showed that sevoflurane preconditioning significantly improved liver-biochemical tests (decreased Alanine transaminase (ALT), Alkaline phosphatase (ALP), Aspartate transaminase (AST) and Alkaline phosphatase (ALP) levels) and limited inflammatory cell infiltration in BALF. Additionally, compared with the LIR group, the reduction in plasma C3 was significantly reduced in the SEVO/LIR group. No significant differences were observed in histological examination in the liver and lung. Immunostaining of the liver for Intracellular Adhesion Molecule 1 (ICAM1) however, showed a decrease in ICAM1 levels in the SEVO/LIR group. In the lung, sevoflurane seemed to exert no effect in ICAM1 levels. Caspase 3 (CASP3) levels in the liver and the lung also appeared unaffected by sevoflurane preconditioning. In the SEVO/LIR group, ICAM1 mRNA expression was significantly reduced in the liver. No statistical significantly differences were observed in Complement component 3 (C3), Complement component 5 (C5) and Clusterin (CLU) mRNA levels in the liver or the lung tissue. Summarizing, sevoflurane preconditioning seems to ameliorate LIR-induced injury in the rats, mediated by mechanisms that include ICAM1 and complement C3 down regulation.

Effect of sevoflurane preconditioning on brain injury induced by cardiopulmonary bypass in rats

Objective To evaluate the effect of sevoflurane preconditioning on brain injury induced by cardiopulmonary bypass(CPB)in rats. Methods Forty adult male Sprague-Dawley rats, aged 6-8 months, weighing 350-450 g, were randomly divided into 5 groups(n=8 each)using a random number table: sham operation group(S group), CPB group, and preconditioning with different concentrations of sevoflurane groups(SP1, SP2 and SP3 groups). In SP1, SP2 and SP3 groups, sevoflurane with the final concentrations of 1.2%, 2.4% and 3.6%, respectively, was inhaled for 1 h, and then CPB was started.After sevoflurane preconditioning and before CPB(T0), at 30 min of CPB(T1), at the end of CPB(T2), and at 1, 2 and 3 h after termination of CPB(T3-5), venous blood samples were collected from the right internal jugular vein for determination of serum S100-β protein concentrations by enzyme-linked immunosorbent assay.Rats were sacrificed at T5, and hippocampi were isolated for determination of neuronal apoptosis(by TUNEL)and NF-κB p65 expression(by immunohistochemistry). Results Compared with group S, the concentration of serum S100-β protein was significantly increased at T1-5, the number of apoptotic neurons was significantly increased, and the expression of NF-κB p65 was significantly up-regulated in CPB, SP1, SP2 and SP3 groups(P<0.05). Compared with group CPB, the serum S100-β protein concentration was significantly decreased at T1-5, the number of apoptotic neurons was significantly decreased, and the expression of NF-κB p65 was significantly down-regulated in SP1, SP2 and SP3 groups(P<0.05). Compared with group SP1, the serum S100-β protein concentration was significantly decreased at T1-5, the number of apoptotic neurons was significantly decreased, and the expression of NF-κB p65 was significantly down-regulated in SP2 and SP3 groups(P<0.05). Compared with group SP2, the serum S100-β protein concentration was significantly decreased at T1-5, the number of apoptotic neurons was significantly decreased, and the expression of NF-κB p65 was significantly down-regulated in group SP3(P<0.05). Conclusion Sevoflurane preconditioning can attenuate CPB-induced brain injury probably by inhibiting activation of NF-κB in hippocampal neurons of rats. Key words: Anesthetics, inhalation; Ischemic preconditioning; Cardiopulmonary bypass; Brain injuries

Effect of Sevoflurane Preconditioning on Inflammatory Cytokines and Oxygen Radicals During Single Lung Ventilation in Patients with Lung Cancer

Objective: To observe the effect of sevoflurane preconditioning on inflammatory cytokines and oxygen radicals during single lung ventilation (SLV) in patients with lung cancer and to discuss the mechanism of sevoflurane induced lung protection. Methods: Thirty patients, ASA I or II, with non-small-cell lung cancer underwent pulmonary surgeries were randomized into two groups: sevoflurane preconditioning group (group S, n=15) and control group (group C, n=15). After general anaesthesia induction. A double-lumen tube was placed and the position was checked by a fibre optic bronchoscope. During the mechanical ventilation, patients in group S, received sevoflurane at 1.0 minimum alveolar concentration (MAC) for 30 min as a preconditioning and then replaced by oxygen for a complete rapid gas exchange to reduce the sevoflurane inhalation concentration to 0 before SLV. While in group C, only intravenous anaesthetic agents, fentanyl and propofol, were administrated before SLV. Blood concentrations of TNF-α, IL-6, IL-8, SOD and MDA were measured at Post-induction of anaesthesia (T1), 30 min after SLV in the lateral position (T2), 60 min after SLV in the lateral position (T3), and at the end of the operation (T4). Results: When compared with Tl, the concentrations of TNF-α, IL-6 and MDA in both groups and the IL-8 in group S were significantly increased at T2-T4 (P<0.05), while the expression of SOD in two groups were decreased significantly(P<0.05). The concentrations of TNF-α, IL-6, IL-8 and MDA in group S were decreased significantly at T2-T4 (P<0.05 or P<0.01) when compared with those in group C. The activity of SOD in group S was significantly increased at T3 and T4 (P<0.05). Conclusion: Sevoflurane preconditioning may moderate the release of inflammatory cytokines to inhibit the inflammatory reaction and may reduce the lipid peroxidation by inhibiting the generation of oxygen free radical. It may protect the lung from the injury during SLV.

Sevoflurane Preconditioning Confers Neuroprotection via Anti-apoptosis Effects.

Neuroprotection against cerebral ischemia afforded by volatile anesthetic preconditioning (APC) has been demonstrated both in vivo and in vitro, yet the underlying mechanism is poorly understood. We previously reported that repeated sevoflurane APC reduced infarct size in rats after focal ischemia. In this study, we investigated whether inhibition of apoptotic signaling cascades contributes to sevoflurane APC-induced neuroprotection. Male Sprague-Dawley rats were exposed to ambient air or 2.4 % sevoflurane for 30 min per day for 4 consecutive days and then subjected to occlusion of the middle cerebral artery (MCAO) for 60 min at 24 h after the last sevoflurane intervention. APC with sevoflurane markedly decreased apoptotic cell death in rat brains, which was accompanied by decreased caspase-3 cleavage and cytochrome c release. The apoptotic suppression was associated with increased ratios of anti-apoptotic Bcl-2 family proteins over pro-apoptotic proteins and with decreased activation of JNK and p53 pathways. Thus, our data suggest that suppression of apoptotic cell death contributes to the neuroprotection against ischemic brain injury conferred by sevoflurane preconditioning.

Sevoflurane Preconditioning Reduces Intestinal Ischemia-Reperfusion Injury: Role of Protein Kinase C and Mitochondrial ATP-Sensitive Potassium Channel

Ischemic preconditioning (IPC) has been considered to be a potential therapy to reduce ischemia-reperfusion injury (IRI) since the 1980s. Our previous study indicated that sevoflurane preconditioning (SPC) also reduced intestinal IRI in rats. However, whether the protective effect of SPC is similar to IPC and the mechanisms of SPC are unclear. Thus, we compared the efficacy of SPC and IPC against intestinal IRI and the role of protein kinase C (PKC) and mitochondrial ATP-sensitive potassium channel (mKATP) in SPC. A rat model of intestinal IRI was used in this study. The superior mesenteric artery (SMA) was clamped for 60 min followed by 120 min of reperfusion. Rats with IPC underwent three cycles of SMA occlusion for 5 min and reperfusion for 5 min before intestinal ischemia. Rats with SPC inhaled sevoflurane at 0.5 minimum alveolar concentration (MAC) for 30 min before the intestinal ischemic insult. Additionally, the PKC inhibitor Chelerythrine (CHE) or mKATP inhibitor 5-Hydroxydecanoic (5-HD) was injected intraperitoneally before sevoflurane inhalation. Both SPC and IPC ameliorated intestinal IRI-induced histopathological changes, decreased Chiu’s scores, reduced terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) positive cells in the epithelium, and inhibited the expression of malondialdehyde (MDA) and tumor necrosis factor-α (TNF-α). These protective effects of SPC were similar to those of IPC. Pretreatment with PKC or mKATP inhibitor abolished SPC—induced protective effects by increasing Chiu’s scores, down-regulated the expression of Bcl-2 and activated caspase-3. Our results suggest that pretreatment with 0.5 MAC sevoflurane is as effective as IPC against intestinal IRI. The activation of PKC and mKATP may be involved in the protective mechanisms of SPC.

Cardioand neuroprotection with volatile anesthetics in cardiac surgery

The researcher's opinions about myocardial and brain anesthetic preconditioning efficiency are yet contradictive. In addition, the anesthetic neuroprotection phenomenon is poorly investigated. In this study the authors attempted to evaluate the efficiency of myocardial and central nervous system (CNS) protection by using a modified method of volatile induction and maintenance of anesthesia (VIMA) based on pulse-like sevoflurane dosing that excludes propofol usage. Ninety CABG patients aged 45-75 years were included in the study group (VIMA) and underwent volatile induction with sevoflurane and anesthetic preconditioning (2 MAC) for 10 min before aortic cross-clamping, with ataralgesia used during CPB. The control group patients (TIVA) received propofol and fentanyl, no inhalation anesthetics were applied. Preoperative concentrations of NTpro-BNP were comparable. There was no significant rise of NTpro-BNP concentration in the VIMA group during the postoperative period. In the TIVA group NTpro-BNP concentrations were 3.8 and 4.8 times as much as the baseline values at 24 and 48 postoperative hours respectively (р&lt;0.05). 17 patients in the VIMA group needed dopamine infusion during 24 postoperative hours, this number was 1.7 times less than that in the TIVA group (23 patients) (р&lt;0.05). VIMA patients had 2-fold lower troponin T concentration in 24 hours after surgery (р&lt;0.01). Significant differences in protein S100B concentrations were observed only during the postoperative period. No significant differences in cognitive functions of the patients from both groups were identified before surgery. On postoperative day 2 MMSE scale count was significantly lower in TIVA patients (20.843.73) in comparison with VI-MA patients (23.364.34) (р&lt;0.05). Thus, the modified VIMA technique with sevoflurane has a greater neuroprotective potential during CABG with CPB and provides better preservation of myocardium structural integrity and cardiac performance than fentanyl/4propofol-based TIVA would do.

Wnt/Glycogen Synthase Kinase 3β/β-catenin Signaling Activation Mediated Sevoflurane Preconditioning-induced Cardioprotection.

Background:Sevoflurane preconditioning (SP) has been shown to invoke potent myocardial protection in animal studies and clinical trials. However, the mechanisms underlying SP are complex and not yet well understood. We investigated the hypothesis that the cardioprotection afforded by SP is mediated via the Wnt/glycogen synthase kinase 3β (GSK3β)/β-catenin signaling pathway.Methods:Two models were established: A Langendorff perfused rat heart model and the H9C2 cell hypoxia/reoxygenation model. Both rats and H9C2 cells were randomly divided into 6 groups as follows: S group, ischemia-reperfusion (I/R) group, DMSO group, IWP group, SP group, and SP + IWP group. Hemodynamic parameters, lactate dehydrogenase (LDH) activity in coronary effluent and cell culture supernatant, and the infarct size were measured to evaluate myocardial ischemia-reperfusion injuries. To determine the activity of Wnt/GSK3β/β-catenin signaling pathway, the expressions of Wnt3a, phospho-GSK3β, and β-catenin were measured by Western blotting.Results:SP improved cardiac function recovery, reduced infarct size (18 ± 2% in the SP group compared with 35 ± 4% in the I/R group; P < 0.05), decreased LDH activity in coronary effluent, and culture supernatant. IWP-2, an inhibitor of Wnt, abolished the cardioprotection by SP. In addition, Western blotting analysis demonstrated that the expressions of Wnt3a, phospho-GSK3β, and β-catenin significantly (P < 0.05) increased in the I/R group, compared with the S group; and compared to I/R group, SP significantly (P < 0.05) increased Wnt3a, phospho-GSK3β, and β-catenin expressions. Pretreatment with IWP-2 significantly (P < 0.05) abolished SP-induced Wnt/GSK3β/β-catenin signaling activation.Conclusions:The results showed for the first time that cardioprotection afforded by SP may be mediated partly via the Wnt/GSK3β/β-catenin signaling pathway.

Identification of miRNAs Involved in the Protective Effect of Sevoflurane Preconditioning Against Hypoxic Injury in PC12 Cells.

The mechanism of sevoflurane preconditioning-induced neuroprotection is poorly understood. This study was aimed at identifying microRNAs (miRNAs) involved in the protective effect of sevoflurane preconditioning against hypoxic injury using the miRCURYTM LNA Array. The screened differentially expressed miRNAs were further validated using qRT-PCR. Finally, after transfection of miRNA (miR-101a or miR-34b) mimics or inhibitor, MTT and flow cytometry assays were used to evaluate cell survival and apoptosis in sevoflurane preconditioning. qRT-PCR confirmed the changes in expression of differentially expressed miRNAs that were screened by the microarray: down-regulation of rno-miR-101a, rno-miR-106b, and rno-miR-294 and up-regulation of rno-miR-883, rno-miR-16, and rno-miR-34b. MiR-101a and miR-34b were the most differentially expressed miRNAs. Sevoflurane preconditioning-inhibited apoptosis and preconditioning-enhanced cell viability of PC12 cells were significantly attenuated by transfection of miR-101a mimetic or miR-34b inhibitors, but were significantly enhanced by transfection of miR-34b mimetic. Therefore, a number of miRNAs, including miR-101a and miR-34b, might play important roles in the neuroprotection induced by sevoflurane preconditioning. Such miRNAs might provide novel targets for preventive and therapeutic strategies against cerebral ischemia-reperfusion injury.

Sevoflurane preconditioning improving cerebral focal ischemia–reperfusion damage in a rat model via PI3K/Akt signaling pathway

In this study, we aimed to assess the neuroprotective effect of sevoflurane preconditioning in a cerebral focal ischemia–reperfusion rat model. Sixty Sprague Dawley rats were divided into six groups: sham operated group, cerebral focal ischemia–reperfusion (CIR) group, CIR+sevoflurane preconditioning (SP) (2%) group, CIR+sevoflurane preconditioning (2.5%) group, CIR+sevoflurane preconditioning (3%) group, and CIR+sevoflurane preconditioning (3.5%) group. All subjects were euthanized 2days post-surgery and their hippocampus tissues were removed. Tissue malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH) and glutathione peroxidase (GSH-Px) levels were measured and hippocampus tissue samples were examined histopathologically. Results showed that significant difference in antioxidant, immunity indexes, and apoptosis-related protein expression was detected in hippocampus tissue between sham-operated control and CIR groups. Sevoflurane preconditioning significantly dose-dependently reduced MDA, IL-1β, IL-6, IL-10 and TNF-α levels and enhanced antioxidant enzyme activities in hippocampus tissue of CIR+SP groups compared to CIR group. In addition, sevoflurane preconditioning significantly dose-dependently upregulated PI3K, p-Akt and Bcl-2 levels and downregulated caspase-3 and Bax levels in hippocampus tissue of CIR+SP groups compared to CIR group. It can be concluded that sevoflurane preconditioning demonstrates a strong and ameliorative effect on cerebral I/R damage in rats. The neuroprotective mechanisms of sevoflurane preconditioning are associated with its properties of anti-apoptosis and anti-oxidation as well as regulation of PI3K and p-Akt signal activation.

Role of HIF-1α in reduction of apoptosis in cortical neurons of rats by sevoflurane preconditioning: the relationship with Bid, Bim and Puma

Objective To evaluate the role of hypoxia inducible factor-1α(HIF-1α)in reduction of apoptosis in cortical neurons of rats by sevoflurane preconditioning. Methods Primary cortical neurons obtained from neonatal Sprague-Dawley rats were seeded in 6-well plates(2 ml/well), and randomly divided into 4 groups(n=15 each)using a random number table: control group(C group), anoxia-reoxygenation(A/R)group, sevoflurane preconditioning group(SP group)and HIF-1α inhibitor 2-methoxyestradiol group(H group). The neurons were subjected to O2-glucose deprivation for 90 min followed by restoration of O2-glucose supply for 24 h. In group SP, the neurons were exposed to 2.0% sevoflurane for 2 h followed by 5 min washout for 3 times, and then sevoflurane preconditioning was performed immediately.In group H, sevoflurane preconditioning was performed at 72 h of incubation with 5 μmol/L 2-methoxyestradiol.The apoptosis in neurons was assessed using Annexin Ⅴ-FITC/PI assay, and apoptosis rate was calculated.The expression of Bid, Bim, Puma and activated caspase-3 in neurons was detected by Western blot. Results Compared with group C, apoptosis rate was significantly increased, and the expression of Bid, Bim, Puma and activated caspase-3 was up-regulated in group A/R.Compared with group A/R, apoptosis rate was significantly decreased, and the expression of Bid, Bim, Puma and activated caspase-3 was down-regulated in group SP.Compared with group SP, apoptosis rate was significantly increased, and the expression of Bid, Bim, Puma and activated caspase-3 was up-regulated in group H. Conclusion HIF-1α mediates reduction of apoptosis in rat neurons by sevoflurane preconditioning, and down-regulated expression of Bid, Bim, and Puma is involved in the mechanism. Key words: Hypoxia-inducible factor 1, alpha subunit; Apoptosis regulatory proteins; Anesthetics, inhalation; Ischemic preconditioning; Cell hypoxia; Oxygen; Neurons; Apoptosis

Effect of apoptosis in neural stem cells treated with sevoflurane.

BackgroundAt present, sevoflurane inhalation anesthesia used on infants is well-known. But long-time exposure to inhalation anesthetic could cause neurologic disorder, especially nerve degeneration in infant and developing brain. The central nervous system degeneration of infants could affect the memory and cognitive function. γ-Aminobutyric acid (GABA) is a known inhibitory neurotransmitter in central nervous system. Inhalation anesthetic sevoflurane may activate GABAA receptor to inhibit central nervous system, leading to apoptosis of neural degeneration, cognitive dysfunction in the critical period of brain development.MethodsNeural stem cells were derived from Wistar embryos, cultured in vitro. Third generation of neural stem cells were randomly divided into four groups according to cultured suspension: Sevoflurane group (Group S), GABAA receptor antagonists, Bicuculline group (Group B), Sevoflurane + GABAA receptor antagonists, Bicuculline group (Group S + B), dimethyl sulphoxide (DMSO) group (Group D). Group B and Group D did not receive sevoflurane preconditioning. Group S and Group S + B were pretreated with 1 minimum alveolar concentration (MAC) sevoflurane for 0 h, 3 h, 6 h, and 12 h. Group S + B and Group B were pretreated with bicuculline (10 uM). Group D was treated with DMSO (10 uL/mL). After treatments above, all groups were cultured for 48 h. Then we measured the cells viability by Cell Counting Kit (CCK-8) assay, cytotoxicity by Lactate Dehydrogenase (LDH) assay, apoptosis ratio with Annexin V/propidium iodide (PI) staining by flow cytometry, and the expression of GABAAR, anti-apoptotic protein Bcl-2, pro-apoptotic protein Bax and Caspase-3 by western blotting.ResultsAfter exposing to sevoflurane for 0 h, 3 h, 6 h, and 12 h with 1MAC, we found that cell viability obviously decreased and cytotoxicity increased in time-dependent way. And Annexin V/PI staining indicated increased apoptosis ratio by flow cytometry. The protein level of GABAA receptor, pro-apoptotic protein Bax and apoptosis protein Caspase-3 increased; while anti-apoptotic protein Bcl-2 decreased. And bicuculline could reverse all detrimental results caused by sevoflurane.ConclusionSevoflurane can inhibit the central nervous system by activating GABAA, resulting in apoptosis of neural stem cells, thus leading to the NSCs degeneration.

Sevoflurane preconditioning-induced neuroprotection is associated with Akt activation via carboxy-terminal modulator protein inhibition

Sevoflurane preconditioning has a neuroprotective effect, but the underlying mechanism is not fully understood. The aim of the present investigation was to evaluate whether sevoflurane-induced cerebral preconditioning involves inhibition of carboxy-terminal modulator protein (CTMP), an endogenous inhibitor of Akt, in a rat model of focal cerebral ischaemia. Male Sprague-Dawley rats were exposed to 2.7% sevoflurane for 45 min. One hour later, rats were subjected to 60 min of focal cerebral ischaemia. The phosphoinositide 3-kinase inhibitors wortmannin and LY294002 were administered 10 min before preconditioning. Rats in the lentiviral transduction group received an intracerebroventricular injection of lentiviral vector Ubi-MCS-CTMP 3 days before ischaemia. Neurological deficits and infarct volumes were evaluated 24 h and 7 days after reperfusion. Phosphorylation of Akt, glycogen synthase kinase-3β (GSK3β), and expression of CTMP were determined at 1, 3, 12, and 24 h after reperfusion. Akt activity was measured at 3 h after reperfusion. Sevoflurane preconditioning improved neurological score and reduced infarct size at 24 h of reperfusion. Pretreatment with wortmannin or LY294002 attenuated these neuroprotective effects. Expression of CTMP correlated with reduced Akt activity after ischaemia, while sevoflurane preconditioning preserved Akt activity and increased phosphorylation of GSK3β. CTMP over-expression diminished the beneficial effects of sevoflurane preconditioning. Activation of Akt signalling via inhibition of CTMP is involved in the mechanism of neuroprotection provided by sevoflurane preconditioning.

Effects of sevoflurane preconditioning and postconditioning on activity of NF-κB during lung ischemia-reperfusion in rats

Objective To evaluate the effects of sevoflurane preconditioning and postconditioning on the activity of NF-κB during lung ischemia-reperfusion (I/R) in rats.Methods Fifty-four adult male Sprague-Dawley rats,weighing 300-350 g,were randomly divided into 3 groups (n =18 each) using a random number table:sham operation group (S group),I/R group and sevoflurane preconditioning and postconditioning group (SPP group).Lung I/R was induced by clamping the left pulmonary hilum for 45 min followed by 120 min reperfusion in I/R and SP groups.The left pulmonary hilum was only isolated but not ligated in group S.In group SP,2.1％ sevoflurane was inhaled for 30 min followed by 10 min washout,the left pulmonary hilum was then ligated for 45 min,and 2.1％ sevoflurane was inhaled for 30 min again starting from onset of reperfusion.Six rats were chosen at 30,60 and 120 min of reperfusion and sacrificed in each group,lungs were removed for determination of wet/dry lung weight (W/D) ratio and content of tumor necrosis factor-α (TNF-α) (by ELISA) and expression of nuclear transcription factor κB (NF-κB) p65 of nuclear protein (by Western blot) and for microscopic examination of the pathologic changes of lungs (with light microscope).Results Compared with S group,W/D ratio,TNF-α content and nuclear protein NF-κB p65 expression in lung tissues were significantly increased at each time point of reperfusion in I/R and SPP groups.Compared with I/R group,W/D ratio,TNF-α content and nuclear protein NF-κB p65 expression in lung tissues were significantly increased at each time point of reperfusion,and the pathological changes of lungs were attenuated in SPP group.Conclusion Sevoflurane preconditioning combined with postconditioning can reduce the lung I/R injury in rats through inhibiting NF-κB activity in lung tissues. Key words: Anesthetics, inhalation; Ischemic preconditioning; Reperfusion injury; Lung; NF-kappa B; Ischemic postconditioning