Postconditioning with sevoflurane protects against focal cerebral ischemia and reperfusion injury via PI3K/Akt pathway

Sevoflurane postconditioning alleviates hypoxic-ischemic brain damage in rats by inhibiting the endoplasmic reticulum stress PERK/ATF4/CHOP pathway

Hypoxic-ischemic brain damage (HIBD) frequently induces cognitive impairments. Investigating the role of sevoflurane postconditioning (SPC) in HIBD, we conducted experiments involving HIBD modeling, SPC treatment, and interventions with the PERK inhibitor GSK2656157 or the PERK activator CCT020312, administered 30 min before modeling, followed by SPC treatment. Behavioral testing using the Morris water maze test and Neurological Deficiency Scale (NDS) was conducted. Additionally, Nissl staining assessed hippocampal CA1 area neuronal density, TUNEL staining evaluated hippocampal CA1 area neuronal apoptosis, and Western blot determined hippocampal CA1 area protein levels, including Bax, Bcl-2, p-PERK/PERK, p-eIF2/eIF2, ATF4, CHOP, GRP78, Bax, and Bcl-2 protein levels. Following SPC treatment, HIBD rats exhibited improved spatial learning and memory abilities, reduced neuronal apoptosis, increased neuronal density in the hippocampal CA1 area, elevated Bcl-2 protein level, decreased Bax protein levels, and decreased levels of endoplasmic reticulum stress pathway related proteins (p-PERK/PERK, p-eIF2/eIF2, ATF4, CHOP and GRP78). Pre-modeling treatment with the PERK inhibitor treatment improved outcomes in HIBD rats. However, pre-modeling treatment with the PERK activator CCT020312 counteracted the protective effects of SPC against HIBD in rats. In conclusion, SPC alleviates neuronal apoptosis in the hippocampus CA1 area of HIBD rats by inhibiting the endoplasmic reticulum stress pathway PERK/ATF4/CHOP, thereby mitigating HIBD in rats.

Pro-Con Debate: Should All General Anesthesia Be Done Using Target-Controlled Propofol Infusion Guided by Objective Monitoring of Depth of Anesthesia?

In this Pro-Con commentary article, we discuss whether all general anesthesia should be done using target-controlled propofol anesthesia guided by monitoring of depth of anesthesia. This is an ongoing debate since more than 25 years, representing a scientific, cultural as well as geographical divide in the anesthesia community. The Pro side argues that total intravenous anesthesia causes less postoperative nausea and higher patient satisfaction than anesthesia using volatile anesthetics. Target-controlled infusion (TCI) of anesthetic agents allows for better titration of intravenous anesthesia using pharmacokinetic models. Processed EEG monitors, such as bispectral index monitoring, allows for better assessing the effect of TCI anesthesia than solely assessment of clinical parameters, such as ECG or blood pressure. The combination of TCI propofol and objective depth of anesthesia monitoring allows creating a pharmacokinetic-pharmacodynamic profile for each patient. Finally, anesthesia using volatile anesthetics poses health risks for healthcare professionals and contributes to greenhouse effect. The Con side argues that for procedures accompanied with ischemia and reperfusion injury of an organ or tissue and for patients suffering from a severe inflammation' the use of volatile anesthetics might well have its advantages above propofol. In times of sudden shortage of drugs, volatile anesthetics can overcome the restriction in the operating theater or even on the intensive care unit, which is another advantage. Volatile anesthetics can be used for induction of anesthesia when IV access is impossible, end-tidal measurements of volatile anesthetic concentration allows confirmation that patients receive anesthetics. Taking environmental considerations into account, both propofol and volatile anesthetics bear certain harm to the environment, be it as waste product or as greenhouse gases. The authors therefore suggest to carefully considering advantages and disadvantages for each patient in its according environment. A well-balanced choice based on the available literature is recommended. The authors recommend careful consideration of advantages and disadvantages of each technique when tailoring an anesthetic to meet patient needs. Where appropriate, anesthesia providers are encouraged to account for unique features of anesthetic drug behavior, patient-reported and observed postoperative outcomes, and economic and environmental considerations when choosing any of the 2 described techniques.

Ischemic Tolerance—A Way to Reduce the Extent of Ischemia–Reperfusion Damage

Individual tissues have significantly different resistance to ischemia–reperfusion damage. There is still no adequate treatment for the consequences of ischemia–reperfusion damage. By utilizing ischemic tolerance, it is possible to achieve a significant reduction in the extent of the cell damage due to ischemia–reperfusion injury. Since ischemia–reperfusion damage usually occurs unexpectedly, the use of preconditioning is extremely limited. In contrast, postconditioning has wider possibilities for use in practice. In both cases, the activation of ischemic tolerance can also be achieved by the application of sublethal stress on a remote organ. Despite very encouraging and successful results in animal experiments, the clinical results have been disappointing so far. To avoid the factors that prevent the activation of ischemic tolerance, the solution has been to use blood plasma containing tolerance effectors. This plasma is taken from healthy donors in which, after exposure to two sublethal stresses within 48 h, effectors of ischemic tolerance occur in the plasma. Application of this activated plasma to recipient animals after the end of lethal ischemia prevents cell death and significantly reduces the consequences of ischemia–reperfusion damage. Until there is a clear chemical identification of the end products of ischemic tolerance, the simplest way of enhancing ischemic tolerance will be the preparation of activated plasma from young healthy donors with the possibility of its immediate use in recipients during the initial treatment.

Experimental and Clinical Aspects of Sevoflurane Preconditioning and Postconditioning to Alleviate Hepatic Ischemia-Reperfusion Injury: A Scoping Review

Ischemia-reperfusion injury (IRI) is an inflammatory process inherent in organ transplantation procedures. It is associated with tissue damage and, depending on its intensity, can impact early graft function. In liver transplantation (LT), strategies to alleviate IRI are essential in order to increase the use of extended criteria donor (ECD) grafts, which are more susceptible to IRI, as well as to improve postoperative graft and patient outcomes. Sevoflurane, a commonly used volatile anesthetic, has been shown to reduce IRI. This scoping review aims to give a comprehensive overview of the existing experimental and clinical data regarding the potential benefits of sevoflurane for hepatic IRI (HIRI) and to identify any gaps in knowledge to guide further research. We searched Medline and Embase for relevant articles. A total of 380 articles were identified, 45 of which were included in this review. In most experimental studies, the use of sevoflurane was associated with a significant decrease in biomarkers of acute liver damage and oxidative stress. Administration of sevoflurane before hepatic ischemia (preconditioning) or after reperfusion (postconditioning) appears to be protective. However, in the clinical setting, results are conflicting. While some studies showed a reduction of postoperative markers of liver injury, the benefit of sevoflurane on clinical outcomes and graft survival remains unclear. Further prospective clinical trials remain necessary to assess the clinical relevance of the use of sevoflurane as a protective factor against HIRI.

AKT/GSK-3β signaling is altered through downregulation of mTOR during cerebral Ischemia/Reperfusion injury

PURPOSE

Cellular responses following cerebral ischemia/reperfusion injury are critical to recovery and survival after ischemic stroke. Understanding of these cellular responses can help the design of therapies to protect brain tissue and promote recovery after stroke. One of these cellular responses may be mediated by the AKT (protein kinase B) signal transduction pathway. This study was aimed to investigate the cerebral ischemia-induced alterations of AKT signaling and the upstream molecular pathways.

METHODS

We modeled cerebral ischemia by middle cerebral artery occlusion in 2-3-month-old male C57BL/6J mice and then analyze the brain samples by using quantitative Western blots and phosphorylation/activation-dependent kinase antibodies. Cerebral ischemia was confirmed by staining of brain slices with 1% 2,3,5-triphenyltetrazolium chloride (TTC) and Nissl, as well as neurological assessments of the mice 24 h after ischemia-reperfusion surgery.

RESULTS

We found marked downregulation of AKT within 12 h of cerebral ischemia/reperfusion, which leads to overactivation of glycogen synthase kinase-3β (GSK-3β). Furthermore, we found that the downregulation of AKT was mediated by downregulation of mTORC2 (the complex 2 of the mechanistic target of rapamycin) instead of its common upstream kinases, phosphatidylinositol 3-kinase and phosphoinositide-dependent kinase-1.

CONCLUSION

Our findings provide new insight into the cellular responses to ischemia/reperfusion brain injury and will help develop new treatments targeting the AKT signaling pathway for the treatment of ischemic stroke.

Targeting focal ischemic and hemorrhagic stroke neuroprotection: Current prospects for local hypothermia

Therapeutic hypothermia (TH) has applications dating back millennia. In modern history, however, TH saw its importation into medical practice where investigations have demonstrated that TH is efficacious in ischemic insults, notably cardiac arrest and hypoxic-ischemic encephalopathy. As well, studies have been undertaken to investigate whether TH can provide benefit in focal stroke (i.e., focal ischemia and intracerebral hemorrhage). However, clinical studies have encountered various challenges with induction and maintenance of post-stroke TH. Most clinical studies have attempted to use body-wide cooling protocols, commonly hindered by side effects that can worsen post-stroke outcomes. Some of the complications and difficulties with systemic TH can be circumvented by using local hypothermia (LH) methods. Additional advantages include the potential for lower target temperatures to be achieved and faster TH induction rates with LH. This systematic review summarizes the body of clinical and preclinical LH focal stroke studies and raises key points to consider for future LH research. We conclude with an overview of LH neuroprotective mechanisms and a comparison of LH mechanisms with those observed with systemic TH. Overall, whereas many LH studies have been conducted preclinically in the context of focal ischemia, insufficient work has been done in intracerebral hemorrhage. Furthermore, key translational studies have yet to be done in either stroke subtype (e.g., varied models and time-to-treat, studies considering aged animals or animals with co-morbidities). Few clinical LH investigations have been performed and the optimal LH parameters to achieve neuroprotection are unknown.

Shogaol potentiates sevoflurane mediated neuroprotection against ischemia/reperfusion-induced brain injury via regulating apoptotic proteins and PI3K/Akt/mTOR/s6K signalling and HIF-1α/HO-1 expression

The current research was intended to evaluate the impact of 6-shogaol in rodent model of ischemic-reperfusion induced- brain injury and also assessed 6-shogaol enhanced sevoflurane's neuroprotective effects. Ischemic-Reperfusion (I/R) injury was induced by middle cerebral artery occlusion (MCAO) method in Sprague-Dawley rats. A separate group of animal was exposed to sevoflurane (2.5%) post-conditioning for 1 h immediately after reperfusion. The 6-shogaol (25 mg or 50 mg/kg body weight) was orally administered to treatment group rats for 14 days and then subjected to I/R. The 6-shogaol treatment along with/without sevoflurane post-conditioning reduced the number of apoptotic cell counts, brain edema and cerebral infarct volume. The western blotting analysis revealed a significant stimulation of the PI3K/Akt/mTOR signal pathway. RT-PCR and western blotting studies revealed improved expressions of HIF-1α and HO-1 at both gene level and protein levels. I/R induced neurological deficits were also alleviated on sevoflurane post-conditioning with/without 6-shogaol treatment. The present findings revealed that pre-treatment with 6-shogoal enhanced the neuroprotective properties of sevoflurane post-conditioning, illustrated the efficacy of the compound against I/R injury.

Sevoflurane protects against ischemia-reperfusion injury in mice after total knee arthroplasty via facilitating RASD1-mediated protein kinase A pathway activation

This study aimed to explore effects of Sevoflurane on ischemia-reperfusion (I/R) injury after total knee arthroplasty (TKA). To explore potential molecular mechanism, Ras related dexamethasone induced 1 (RASD1), a Protein kinase A (PKA) activator, frequently associated with various models of I/R injury, was also investigated. In vivo mouse models with I/R injury after TKA and in vitro cell models with I/R injury were induced. Contents of creatinine kinase (CK), lactic dehydrogenase (LDH), superoxide dismutase (SOD), and malondialdehyde (MDA), serum levels of inflammatory factors, expression of PKA pathway-related genes and cell proliferation and apoptosis were measured. RASD1 was altered and PKA pathway was inhibited in mice and cells to elucidate the involvement of RASD1 and PKA pathway in Sevoflurane treatment on I/R injury. RASD1 was upregulated in I/R injury after TKA. Sevoflurane treatment or silencing RASD1 reduced RASD1 expression, CK, LDH and MDA contents, inflammation, apoptosis, but increased proliferation, SOD content, cAMP expression, and extents of PKA and cAMP responsive element binding protein (CREB) phosphorylation in skeletal muscle cells of I/R injury. Additionally, PKA pathway activation potentiated the therapeutic effect of Sevoflurane on I/R injury after TKA. Altogether, Sevoflurane treatment confines I/R injury after TKA via RASD1-mediated PKA pathway activation.

Postconditioning with Sevoflurane or Propofol Alleviates Lipopolysaccharide-Induced Neuroinflammation but Exerts Dissimilar Effects on the NR2B Subunit and Cognition

Neuroinflammation can cause cognitive deficits, and preexisting neuroinflammation is observed frequently in the clinic after trauma, surgery, and infection. Patients with preexisting neuroinflammation often need further medical treatment under general anesthesia. However, the effects of postconditioning with general anesthetics on preexisting neuroinflammation have not been determined. In this study, adult rats were posttreated with sevoflurane or propofol after intracerebroventricular administration of lipopolysaccharide. The effects of sevoflurane or propofol postconditioning on neuroinflammation-induced recognition memory deficits were detected. Our results found that postconditioning with sevoflurane but not propofol reversed the selective spatial recognition memory impairment induced by neuroinflammation, and these differential effects did not appear to be associated with the similar anti-neuroinflammatory responses of general anesthetics. However, postconditioning with propofol induced a selective long-lasting upregulation of extrasynaptic NR2B-containing N-methyl-D-aspartate receptors in the dorsal hippocampus, which downregulated the cAMP response element-binding signaling pathway and impaired spatial recognition memory. Additionally, the NR2B antagonists memantine and Ro25-6981 reversed this neurotoxicity induced by propofol postconditioning. Taken together, these results indicate that under preexisting neuroinflammation, postconditioning with sevoflurane can provide reliable neuroprotection by attenuating lipopolysaccharide-induced neuroinflammation, apoptosis, and neuronal loss and eventually improving spatial recognition deficits. However, although posttreatment with propofol also has the same anti-neuroinflammatory effects, the neurotoxicity caused by propofol postconditioning following neuroinflammation warrants further consideration.

Sevoflurane Postconditioning Attenuates Hepatic Ischemia-Reperfusion Injury by Limiting HMGB1/TLR4/NF-κB Pathway via Modulating microRNA-142 in vivo and in vitro

Preconditioning of sevoflurane (Sevo) has been demonstrated to protect the liver from ischemia/reperfusion (I/R) injury. However, it is unknown whether it has hepatoprotective when given at the onset of reperfusion (postconditioning), a protocol with more clinical impact. The present study aimed to explore the hepatoprotective effects of Sevo postconditioning against hepatic IR injury in vivo and in vitro and the possible mechanisms. Using a mouse model of hepatic I/R, Sevo postconditioning significantly improved hepatic injury after reperfusion, as demonstrated by reduced AST, ALT, and LDH serum levels and reduced histologic damage in liver tissues. Furthermore, Sevo postconditioning could suppress the apoptosis, inhibit oxidative stress and inflammatory response in liver tissue of HIRI mice, as well as improve the survival rate of HIRI mice. Through analyzing GSE72314 from the gene expression omnibus (GEO) database, it was demonstrated that microRNA (miR)-142 is downregulated by HIRI, which was reversed by Sevo treatment. Further investigation showed that agomiR-142 injection could enhance the hepatoprotective effects of Sevo postconditioning on I/R injury, while antagomiR-142 reversed these effects in mice. Notably, high mobility group box 1 (HMGB1), an important inflammatory factor, was directly targeted by miR-142 in hepatic cells, and we further found that Sevo could inhibit the expression of HMGB1 through up-regulating miR-142 expression in HIRI mice model. In addition, we found that I/R injury induced the activation of TLR4/NF-κB inflammatory pathway was partially suppressed by Sevo postconditioning, and miR-142 mediated the regulatory role of Sevo postconditioning. In line with the in vivo results, Sevo treatment improved the cell viability, inhibited cell apoptosis, oxidative stress and inflammatory response in vitro HIRI model, while these effects were reversed by antagomiR-142 transfection. Collectively, our findings demonstrated that Sevo postconditioning counteracts the downregulation of miR-142 provoked by I/R, in turn decreased the expression of HMGB1, blocking TLR4/NF-κB pathway activation, thus improving hepatic I/R injury. Our data suggest that Sevo may be a valuable alternative anaesthetic agent in liver transplantation and major liver surgeries.

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.

Molecular Aspects of Volatile Anesthetic-Induced Organ Protection and Its Potential in Kidney Transplantation

Ischemia reperfusion injury (IRI) is inevitable in kidney transplantation and negatively impacts graft and patient outcome. Reperfusion takes place in the recipient and most of the injury following ischemia and reperfusion occurs during this reperfusion phase; therefore, the intra-operative period seems an attractive window of opportunity to modulate IRI and improve short- and potentially long-term graft outcome. Commonly used volatile anesthetics such as sevoflurane and isoflurane have been shown to interfere with many of the pathophysiological processes involved in the injurious cascade of IRI. Therefore, volatile anesthetic (VA) agents might be the preferred anesthetics used during the transplantation procedure. This review highlights the molecular and cellular protective points of engagement of VA shown in in vitro studies and in vivo animal experiments, and the potential translation of these results to the clinical setting of kidney transplantation.

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.

Advances in intervention methods and brain protection mechanisms of in situ and remote ischemic postconditioning

Ischemic postconditioning (PostC) conventionally refers to a series of brief blood vessel occlusions and reperfusions, which can induce an endogenous neuroprotective effect and reduce cerebral ischemia/reperfusion (I/R) injury. Depending on the site of adaptive ischemic intervention, PostC can be classified as in situ ischemic postconditioning (ISPostC) and remote ischemic postconditioning (RIPostC). Many studies have shown that ISPostC and RIPostC can reduce cerebral IS injury through protective mechanisms that increase cerebral blood flow after reperfusion, decrease antioxidant stress and anti-neuronal apoptosis, reduce brain edema, and regulate autophagy as well as Akt, MAPK, PKC, and KATP channel cell signaling pathways. However, few studies have compared the intervention methods, protective mechanisms, and cell signaling pathways of ISPostC and RIPostC interventions. Thus, in this article, we compare the history, common intervention methods, neuroprotective mechanisms, and cell signaling pathways of ISPostC and RIPostC.

Isoflurane versus sevoflurane for early brain injury and expression of sphingosine kinase 1 after experimental subarachnoid hemorrhage

The first step to treat aneurysmal subarachnoid hemorrhage (SAH) is aneurysmal obliteration under general anesthesia but not treat the SAH itself and the secondary effects. However, the identification of anesthetics with properties that help to attenuate post-SAH brain injury can be useful for improving outcomes of SAH patients. We examined whether 2% isoflurane and 3% sevoflurane posttreatment are protective against early brain injury (EBI) after SAH. This study used 87 8-week-old male CD-1 mice. We induced SAH by endovascular perforation in mice. Animals were randomly divided into 4 groups: sham-operated (n = 16), SAH + vehicle-medical air (n = 26), SAH + 2% isoflurane (n = 22), and SAH + 3% sevoflurane (n = 23). Neurobehavioral function, brain water content and Western blotting were evaluated at 24 h. The expression of sphingosine kinase (SphK), cleaved caspase-3 and cyclooxygenase-2 (COX2) was determined by Western blotting. Cell death was examined by terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling staining. Both 2% isoflurane and 3% sevoflurane significantly improved neurobehavioral function, and brain edema at 24 h after SAH and attenuated cell death, associated with an increase in SphK1, a decrease in cleaved caspase-3 and COX2. The neuroprotective effects were similar between 2% isoflurane and 3% sevoflurane. These findings suggest that both 2% isoflurane and 3% sevoflurane significantly inhibited EBI by suppressing post-SAH apoptosis and brain inflammation possibly via the SphK1-related pathway.

Cold stress protein RBM3 responds to hypothermia and is associated with good stroke outcome

RNA-binding motif protein 3 is a molecular marker of hypothermia that has proved neuroprotective in neurodegenerative disease models. However, its relationship to the well-recognized therapeutic effect of hypothermia in ischaemic stroke had not been studied. In this work, the expression of RNA-binding motif protein 3 was investigated in ischaemic animal models subjected to systemic and focal brain hypothermia, specifically the effects of RNA-binding motif protein 3 silencing and overexpression on ischaemic lesions. Moreover, the association of RNA-binding motif protein 3 levels with body temperature and clinical outcome was evaluated in two independent cohorts of acute ischaemic stroke patients (n = 215); these levels were also determined in a third cohort of 31 patients derived from the phase III EuroHYP-1 trial of therapeutic cooling in ischaemic stroke. The preclinical data confirmed the increase of brain RNA-binding motif protein 3 levels in ischaemic animals subjected to systemic and focal hypothermia; this increase was selectively higher in the cooled hemisphere of animals undergoing focal brain hypothermia, thus confirming the direct effect of hypothermia on RNA-binding motif protein 3 expression, while RNA-binding motif protein 3 up-regulation in ischaemic brain regions led to functional recovery. Clinically, patients with body temperature <37.5°C in the first two cohorts had higher RNA-binding motif protein 3 values at 24 h and good outcome at 3 months post-ischaemic stroke, while RNA-binding motif protein 3 levels in the cooled third cohort tended to exceed those in placebo-treated patients. These results make RNA-binding motif protein 3 a molecular marker associated with the effect of hypothermia in ischaemic stroke and suggest its potential application as a promising protective target.

Kaempferol Protects Against Cerebral Ischemia Reperfusion Injury Through Intervening Oxidative and Inflammatory Stress Induced Apoptosis

The aim of this research is to investigate the potential neuro-protective effect of kaempferol which with anti-oxidant, anti-inflammatory, and immune modulatory properties, and understand the effect of kaempferol on reducing cerebral ischemia reperfusion (I/R) injury in vivo. Male adult Sprague Dawley (SD) rats were pretreated with kaempferol for one week via gavage before cerebral I/R injury operation. We found that kaempferol treatment can reduce the cerebral infarct volume and neurological score after cerebral I/R. Rats were sacrificed after 24 h reperfusion. We observed that kaempferol improved the arrangement, distribution, and morphological structure of neurons, as well as attenuated cell apoptosis in brain tissue via hematoxylin and eosin (H&E) staining, Nissl staining and TUNEL staining. Superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione peroxidase (GSH) kit analysis, enzyme-linked immunosorbent (ELISA) assay, real-time PCR, Western blot, and immunohistochemical examination indicated that kaempferol mitigated oxidative and inflammatory stress via regulating the expression of proteins, p-Akt, p-GSK-3β, nuclear factor erythroid2-related factor 2 (Nrf-2), and p-NF-κB during cerebral I/R, thus increasing the activity of SOD and GSH, meanwhile decreasing the content of MDA in serum and brain tissue, as well as restoring the expression levels of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 in vivo. Taken together, this study suggested that kaempferol protects against cerebral I/R induced brain damage. The possible mechanism is related with inhibiting oxidative and inflammatory stress induced apoptosis.

Isorhapontigenin alleviates cerebral ischemia/reperfusion injuries in rats and modulated the PI3K/Akt signaling pathway

Isorhapontigenin (ISO) is one of the main bioactive components of Gnetum cleistostachyum and was shown to possess antioxidant and antitumor functions. Herein, we hope to examine the neuroprotection impacts of ISO in rats subjected to transient middle cerebral artery occlusion/reperfusion (MCAO/R, 2/24 h) injuries. ISO was injected intraperitoneally into the rats immediately after cerebral ischemia. After 24 h of the reperfusion, infarct volume, brain water contents, neurological deficit, and cerebral blood flow were assessed. Hippocampus histopathology change was detected by H&E and TUNEL staining. The expressions of cleaved caspase-3, Bax and Bcl-2, and phospho-Akt (p-Akt) were investigated by real-time RT-PCR or western blot analysis. We found that ISO significantly suppressed the infarct volumes, brain water contents, and neurological deficit, increased CBF, and relieved histopathologic change in a dose-dependent manner. Reduced malondialdehyde (MDA) and elevated activities of superoxide dismutase (SOD) and GSH and glutathione peroxidase (GSH-PX) were observed in ISO group. ISO remarkably decreased caspase-3 and Bax and increased levels of Bcl-2. Additionally, ISO upregulated p-Akt expression. Blocking of PI3K activities by wortmannin can abolish the ISO-caused decrease in infarct volumes and neurologic deficit scores and abrogate the promotion of p-Akt. The data indicated that ISO played neuroprotective impacts against focal I/R injuries, possibly related to the activating of PI3K/Akt signaling.

Sevoflurane postconditioning improves spatial learning and memory ability involving mitochondrial permeability transition pore in hemorrhagic shock and resuscitation rats

BACKGROUND

Hemorrhagic shock induces the cognitive deficiency. Sevoflurane postconditioning has been documented to provide neuroprotection against ischemic-reperfusion injury by suppressing apoptosis. Mitochondrial permeability transition pore (mPTP) plays an important role in apoptosis, but it is unknown if the protective effect of sevoflurane postconditioning on hemorrhagic shock and resuscitation is associated with the change of mPTP opening. Hence, the aim of the study was to find out the precise mechanism of the sevoflurane postconditioning.

METHODS

Sprague Dawley rats were subjected to hemorrhage shock for 60 min and then exposed to 2.4% sevoflurane for 30 min at the instant of reperfusion. Additionally, an opener (atractyloside) or an inhibitor (cyclosporine A) of mPTP was used in the animal model before sevoflurane postconditioning. Rats were randomly assigned into groups of Sham, Shock, Shock+Sevoflurane, Shock+Atractyloside, Shock+Sevoflurane+Atractyloside, Shock+Cyclosporin A, and Shock+Sevoflurane+Cyclosporin A treatment. Rat behavior was assessed for 5 days by Morris water maze 72 hr after surgery, and then hippocampus CA1 region was immunohistochemically stained. Brains were harvested 24 hr after surgery to detect the protein expression levels of Bcl-2, Bax, and cytochrome C by Western blot, the changes of mPTP opening, and mitochondrial membrane potential (MMP).

RESULTS

We found that sevoflurane postconditioning significantly improved rats' spatial learning and memory ability, down-regulated the expression of Bax, cytochrome C, and caspase-3, up-regulated the expression of Bcl-2, decreased the mPTP opening, and increased the MMP. The neuroprotective effect of sevoflurane postconditioning was abolished by atractyloside, but cyclosporin A played the similar protective role as sevoflurane postconditioning.

CONCLUSION

These findings proved that sevoflurane postconditioning improved spatial learning and memory ability in hemorrhage shock and resuscitation rats, the mechanism of which may be related to block mPTP opening, increase MMP, and reduce neuron apoptosis in the hippocampus.

Plasma amyloid beta level changes in aged mice with cognitive dysfunction following sevoflurane exposure

INTRODUCTION

Previous studies have stated that cognitive impairment induced by anesthetics was associated with amyloid beta (Aβ). However, few researchers have investigated the transport of Aβ inside and outside of the brain.

AIM

We attempted to probe the effects of sevoflurane on cognitive functions, the plasma Aβ, and transporters of Aβ in aged mice. The receptor for advanced glycation end-products (RAGE) is an Aβ influx protein, and Low-density lipoprotein receptor-related protein-1 (LRP-1) is an Aβ efflux protein.

METHODS

Aged mice were divided into the control group and the sevoflurane group. The mice were exposed to 100% oxygen or 2.5% sevoflurane for 2 h. The abilities of spatial learning and memory in mice were tested using the Morris water maze. Aβ concentrations of plasma were measured with enzyme-linked immunosorbent assay kits. The RAGE and LRP-1 gene levels in the brain were assessed with quantitative polymerase chain reaction, and the protein levels were determined by western blot analysis. The locations of RAGE in the brain were confirmed via immunofluorescence.

RESULTS

In the sevoflurane group mice, the escape latency was increased on the 5th day of training, and the time spent in the target quadrant was decreased on the 7th day after anesthesia. Sevoflurane reduced the concentration of plasma Aβ1-40. In addition, sevoflurane increased both gene and protein levels of RAGE in the brain, and increased RAGE proteins co-localized with the hippocampal vascular endothelial cells.

CONCLUSION

RAGE over-expression in the hippocampal vascular endothelial cells possibly resulted in the excessive transport of the plasma Aβ1-40 into the brain after treatment with sevoflurane, which was associated with sevoflurane-induced cognitive dysfunction in aged mice.

Inhibition of the PI3K/Akt signaling pathway impedes the restoration of neurological function following hypoxic-ischemic brain damage in a neonatal rabbit model

OBJECTIVE

Hypoxic-ischemic brain damage (HIBD), frequently occurring in infancy and childhood, is a major cause of mortality and severe neurologic impairment. This study was performed to examine the effect of the PI3K/Akt signaling pathway on HIBD in a neonatal rabbit model.

MATERIALS AND METHODS

Uterine artery occlusion was used to establish HIBD models in neonatal rabbits, which were then subjected to sham operation, dimethyl sulfoxide (2 mL) or LY294002 (inhibitor of PI3K/Akt signaling pathway, 6.4 μg/kg). Behavioral neurological assessment was performed in neonatal rabbits delivered by cesarean section, after which serum neuron-specific enolase (NSE) level and cerebral water content were determined. The level of cleaved caspase-3 level and apoptosis of neurons were observed by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. Furthermore, the expression of PI3K/Akt signaling pathway- and apoptosis-related factors was examined.

RESULTS

In neonatal rabbits, HIBD increased the fetal death rate; reduced neurological scores of posture, righting reflex, and deglutition reflex; elevated serum NSE levels, cerebral water content, cleaved caspase-3-positive expression in hippocampal CA1 region and apoptotic neurons; inactivated PI3K/Akt signaling pathway as well as reduced Bcl-2 expression and increased BAD and Bax expression. Notably, the treatment of LY294002 further aggravated neurological impairment in neonatal rabbits in response to HIBD.

CONCLUSION

Following the HIBD caused by intrauterine asphyxia, the LY294002 administered through auricular vein infusion into pregnant rabbits exacerbates neurological impairment of neonatal rabbits, suggesting that inhibition of PI3K/Akt signaling pathway may serve as a candidate therapeutic target for neurological recovery.

Volatile anaesthetics and postoperative delirium in older surgical patients-A secondary analysis of prospective cohort studies

BACKGROUND

Volatile Anaesthetics (VAs) may be associated with postoperative delirium (POD). However, to date, the effects of VAs on POD are not completely understood. The objective of this study was to investigate the incidence of POD in different VA groups.

METHODS

A secondary analysis was conducted using a database created from prospective cohort studies in patients who underwent elective major noncardiac surgery. Patients who received general anaesthesia with desflurane, isoflurane, or sevoflurane were included in the study. POD occurring on either of the first two postoperative days was measured using the Confusion Assessment Method.

RESULTS

Five hundred and thirty-two patients were included in this study, with a mean age of 73.5 ± 6.0 years (range, 65-96 years). The overall incidence of POD on either postoperative day 1 or 2 was 41%. A higher incidence of POD was noted in the desflurane group compared with the isoflurane group (Odds Ratio = 3.35, 95% CI = 1.54-7.28). The incidence of POD between the sevoflurane and isoflurane or desflurane group was not statistically significant.

CONCLUSION

Each VA may have different effects on postoperative cognition. Further studies using a prospective randomized approach will be necessary to discern whether anaesthetic type or management affects the occurrence of postoperative delirium.

The Antiapoptosis Effect of Geum japonicum Thunb. var. chinense Extracts on Cerebral Ischemia Reperfusion Injury via PI3K/Akt Pathway

Geum japonicum Thunb. var. chinense (GJ) is a type of wild vegetable found in China and other Asian countries; it has been reported that its extracts possess a neuroprotective effect against cerebral ischemia reperfusion (CIR) injury. The aim of this study is to explore the effect GJ extracts on transient focal CIR injury and neurons apoptosis and to clarify its possible underlying mechanisms in vivo. Our results indicated that pretreatment with GJ extracts significantly ameliorated the infarct volume, decreased neurological deficits, lessened neural cells apoptosis, downregulated GFAP activity level, and increased surviving neurons. Moreover, GJ extracts preadministration increased Bcl-2 levels and attenuated the increase in the expressions of Bax and it also lowered the cleaved caspase-3 activity in ischemic cortex tissues which was caused by CIR and increased the expression of PI3K and p-Akt. The above effects of high dose of GJ (GJ-H) group were much better than those of low dose of GJ (GJ-L), which indicated that GJ extracts may be helpful in the suppression of CIR injury with a dose-dependent manner.

Sevoflurane exerts brain-protective effects against sepsis-associated encephalopathy and memory impairment through caspase 3/9 and Bax/Bcl signaling pathway in a rat model of sepsis

Objective We compared the effects of sevoflurane and isoflurane on systemic inflammation, sepsis-associated encephalopathy, and memory impairment in a rat sepsis model of cecal ligation and puncture (CLP)-induced polymicrobial peritonitis. Methods Twenty-four rats were assigned to sham, CLP, CLP + sevoflurane, and CLP + isoflurane groups. At 72 hours after CLP, the rats underwent behavior tests. Serum cytokines were evaluated. Brain tissue samples were collected for determination of glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase; the wet/dry weight ratio; myeloperoxidase (MPO) and malondialdehyde (MDA); apoptotic gene release; and histologic examinations. Results The MPO level, wet/dry weight ratio, and histopathology scores were lower and the Bcl2a1 and Bcl2l2 expressions were upregulated in both the CLP + sevoflurane and CLP + isoflurane groups compared with the CLP group. The interleukin-6, interleukin-1β, MDA, and caspase 3, 8, and 9 levels were lower; the GPX, SOD, Bax, Bcl2, and Bclx levels were higher; and non-associative and aversive memory were improved in the CLP + sevoflurane group compared with the CLP + isoflurane group. Conclusion Sevoflurane decreased apoptosis and oxidative injury and improved memory in this experimental rat model of CLP. Sevoflurane sedation may protect against brain injury and memory impairment in septic patients.

Postconditioning with sevoflurane ameliorates spatial learning and memory deficit via attenuating endoplasmic reticulum stress induced neuron apoptosis in a rat model of hemorrhage shock and resuscitation

Hemorrhage shock could initiate endoplasmic reticulum stress (ERS) and then induce neuronal apoptosis. The aim of this study was to investigate whether sevoflurane postconditioning could attenuate brain injury via suppressing apoptosis induced by ERS. Seventy male rats were randomized into five groups: sham, shock, low concentration (sevo1, 1.2%), middle concentration (sevo2, 2.4%) and high concentration (sevo3, 3.6%) of sevoflurane postconditioning. Hemorrhage shock was induced by removing 40% of the total blood volume during an interval of 30 min. 1 h after the completion of bleeding, the animals were reinfused with shed blood during the ensuing 30 min. The spatial learning and memory ability of rats were measured by Morris water maze (MWM) test three days after the operation. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positive cells in the hippocampus CA1 region were assessed after the MWM test. The expression of C/EBP-homologousprotein (CHOP) and glucose-regulated protein 78 (GRP78) in the hippocampus were measured at 24 h after reperfusion. We found that sevoflurane postconditioning with the concentrations of 2.4% and 3.6% significantly ameliorated the spatial learning and memory ability, decreased the TUNEL-positive cells, and reduced the GRP78 and CHOP expression compared with the shock group. These results suggested that sevoflurane postconditioning with the concentrations of 2.4% and 3.6% could ameliorate spatial learning and memory deficit after hemorrhage shock and resuscitation injury via suppressing apoptosis induced by ERS.

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.

Kappa-opioid receptor agonist U50448H protects against renal ischemia-reperfusion injury in rats via activating the PI3K/Akt signaling pathway

Renal ischemia-reperfusion injury (IRI) is regarded as a leading cause of acute kidney failure and renal dysfunction. Previous studies show that kappa opioid receptor (KOR) agonists can attenuate IRI in cardiomycytes and neuronal cells. In this study we explored the effects of a KOR agonist on renal IRI and the underlying mechanisms in vivo and in vitro. An IRI model was established in SD rats, which were intravenously pretreated with a KOR agonist U50448H (1 mg/kg), a KOR antagonist Nor-BNI (2 mg/kg) followed by U50448H (1 mg/kg), or the PI3K inhibitor wortmannin (1.4 mg/kg) followed by U50448H (1 mg/kg). U50448H pretreatment significantly decreased the serum levels of creatinine (Cr) and BUN, the renal tubular injury scores and the apoptotic index (AI) in IRI model rats. Furthermore, U50448H significantly increased SOD activity and NO levels, and reduced the MDA levels in the kidney tissues of IRI model rats. Moreover, U50448H significantly increased the phosphorylation of Akt, eNOS and PI3K in the kidney tissues of IRI model rats. All the beneficial effects of U50448H were blocked by Nor-BNI or wortmannin pre-administered. Similar results were observed in vitro in renal tubular epithelial NRK-52E cells subjected to a hypoxia-reoxygenation (HR) procedure. Our results demonstrate that the KOR agonist U50448H protects against renal IRI via activating the PI3K/Akt signaling pathway.

Sevoflurane inhibits the malignant potential of head and neck squamous cell carcinoma via activating the hypoxia‑inducible factor-1α signaling pathway in vitro

Sevoflurane, an inhalational anesthetic, is extensively used during oral cancer surgery. However, the effect of sevoflurane on head and neck squamous cell carcinoma (HNSCC) remains unclear. The objective of the present study was to investigate the effects of sevoflurane on the proliferation, apoptosis and invasion in HNSCC cell lines and the underlying molecular mechanism. The Cell Counting Kit-8 assay was used to evaluate cell proliferation. Apoptosis was analyzed by flow cytometry. Cell invasion was evaluated using the Transwell invasion assay. The expression levels of Akt, p-Akt (Ser473), hypoxia‑inducible factor-1α (HIF-1α), Fas and Bcl-2 were measured by western blotting. Significant inhibition of cell proliferation and induction of apoptosis were observed in FaDu and CAL-27 cells following sevoflurane treatment. The expression of Akt, p-Akt (Ser473) and Bcl-2 was supressed, while that of Fas was significantly increased, which was partly associated with the activation of the HIF-1α pathway. In addition, the results revealed a statistically significant inhibition of cell invasion in the FaDu cell line following exposure to 2 and 4% sevoflurane for 2, 4, 6 and 8 h. Therefore, the present study demonstrated that sevoflurane decreased the malignant behavior of HNSCC cell lines in vitro, which was associated with activation of the HIF-1α pathway.

RETRACTED: Dexmedetomidine exerts neuroprotective effect via the activation of the PI3K/Akt/mTOR signaling pathway in rats with traumatic brain injury

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figures 3A, 5C and 7A which appear to have a similar phenotype as many other publications, as detailed here: https://pubpeer.com/publications/7D9475A7397928053FFE9442F8E943; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. Several additional suspected image duplication issues were also identified in Figures 3A, 5A, and 7A. The journal requested the corresponding authors comment on these concerns and provide the raw data. The authors were unable to provide a satisfactory explanation or the raw data. The Supervision Committee of the National Natural Science Foundation of China launched an investigation into several papers of Jiangsu Normal University, including this one, and found evidence of "Falsification of pictures or data, fabrication of research process, use of others' signatures without consent, and false information in project final reports", as detailed here: https://www.nsfc.gov.cn/publish/portal0/tab442/info85495.htm. The Academic Committee at Jiangsu Normal University requested retraction of the article. The Editor-in-Chief assessed the case and decided to retract the article.

Transient Cerebral Ischemia Alters GSK-3β and p-GSK-3β Immunoreactivity in Pyramidal Neurons and Induces p-GSK-3β Expression in Astrocytes in the Gerbil Hippocampal CA1 Area

Glycogen synthase kinase 3β (GSK-3β) is a key downstream protein in the PI3K/Akt pathway. Phosphorylation of serine 9 of GSK-3β (GSK-3β activity inhibition) promotes cell survival. In this study, we examined changes in expressions of GSK-3β and phosphorylation of GSK-3β (p-GSK-3β) in the gerbil hippocampal CA1 area after 5 min of transient cerebral ischemia. GSK-3β immunoreactivity in the CA1 area was increased in pyramidal cells at 6 h after ischemia-reperfusion. It was decreased in CA1 pyramidal cells from 12 h after ischemia-reperfusion, and hardly detected in the CA1 pyramidal cells at 5 days after ischemia-reperfusion. p-GSK-3β immunoreactivity was slightly decreased in CA1 pyramidal cells at 6 and 12 h after ischemia-reperfusion. It was significantly increased in these cells at 1 and 2 days after ischemia-reperfusion. Five days after ischemia-reperfusion, p-GSK-3β immunoreactivity was hardly found in CA1 pyramidal cells. However, p-GSK-3β immunoreactivity was strongly expressed in astrocytes primarily distributed in strata oriens and radiatum. In conclusion, GSK-3β and p-GSK-3β were significantly changed in pyramidal cells and/or astrocytes in the gerbil hippocampal CA1 area following 5 min of transient cerebral ischemia. This finding indicates that GSK-3β and p-GSK-3β are closely related to delayed neuronal death.

TASK channels contribute to neuroprotective action of inhalational anesthetics

Postconditioning with inhalational anesthetics can reduce ischemia-reperfusion brain injury, although the cellular mechanisms for this effect have not been determined. The current study was designed to test if TASK channels contribute to their neuroprotective actions. Whole cell recordings were used to examine effects of volatile anesthetic on TASK currents in cortical neurons and to verify loss of anesthetic-activated TASK currents from TASK^−/− mice. A transient middle cerebral artery occlusion (tMCAO) model was used to establish brain ischemia-reperfusion injury. Quantitative RT-PCR analysis revealed that TASK mRNA was reduced by >90% in cortex and hippocampus of TASK^−/− mice. The TASK^−/− mice showed a much larger region of infarction than C57BL/6 J mice after tMCAO challenge. Isoflurane or sevoflurane administered after the ischemic insult reduced brain infarct percentage and neurological deficit scores in C57BL/6 J mice, these effect were reduced in TASK^−/− mice. Whole cell recordings revealed that the isoflurane-activated background potassium current observed in cortical pyramidal neurons from wild type mice was conspicuously reduced in TASK^−/− mice. Our studies demonstrate that TASK channels can limit ischemia-reperfusion damage in the cortex, and postconditioning with volatile anesthetics provides neuroprotective actions that depend, in part, on activation of TASK currents in cortical neurons.

β-Caryophyllene Pretreatment Alleviates Focal Cerebral Ischemia-Reperfusion Injury by Activating PI3K/Akt Signaling Pathway

β-Caryophyllene (BCP) has been reported to be protective against focal cerebral ischemia-reperfusion (I/R) injury by its anti-oxidative and anti-inflammatory features. Recent study demonstrates that the BCP exhibits potential neuroprotection against I/R injury induced apoptosis, however, the mechanism remains unknown. Therefore, we investigate the underlying anti-apoptotic mechanism of BCP pretreatment in I/R injury. Sprague-Dawley rats (pretreated with BCP suspensions or solvent orally for 7 days) were subjected to transient Middle Cerebral Artery Occlusion (MCAO) for 90 min, followed by 24 h reperfusion. Results showed that BCP pretreatment improved the neurologic deficit score, lowered the infarct volume and decreased number of apoptotic cells in the hippocampus. Moreover, in western blot and RT-qPCR detections, BCP pretreatment down-regulated the expressions of Bax and p53, up-regulated the expression of Bcl-2, and enhanced the phosphorylation of Akt on Ser473. Blockage of PI3K activity by wortmannin not only abolished the BCP-induced decreases in infarct volume and neurologic deficit score, but also dramatically abrogated the enhancement of AKt phosphorylation. Our results suggested that BCP pre-treatment protects against I/R injury partly by suppressing apoptosis via PI3K/AKt signaling pathway activation.

Enhanced neuroinflammation mediated by DNA methylation of the glucocorticoid receptor triggers cognitive dysfunction after sevoflurane anesthesia in adult rats subjected to maternal separation during the neonatal period

BACKGROUND

Mounting evidence indicates that children who experience abuse and neglect are prone to chronic diseases and premature mortality later in life. One mechanistic hypothesis for this phenomenon is that early life adversity alters the expression or functioning of the glucocorticoid receptor (GR) throughout the course of life and thereby increases sensitivity to inflammatory stimulation. An exaggerated pro-inflammatory response is generally considered to be a key cause of postoperative cognitive dysfunction (POCD). The aim of this study was to examine the effects of early life adversity on cognitive function and neuroinflammation after sevoflurane anesthesia in adult rats and to determine whether such effects are associated with the epigenetic regulation of GR.

METHODS

Wistar rat pups were repeatedly subjected to infant maternal separation (early life stress) from postnatal days 2-21. In adulthood, their behavior and the signaling of hippocampal pro-inflammatory factors and nuclear factor-kappa B (NF-κB) after sevoflurane anesthesia were evaluated. We also examined the effects of maternal separation (MS) on the expression of GR and the DNA methylation status of the promoter region of exon 1₇ of GR and whether behavioral changes and neuroinflammation after anesthesia were reversible when the expression of GR was increased by altering DNA methylation.

RESULTS

MS induced cognitive decline after sevoflurane inhalation in the Morris water maze and context fear conditioning tests and enhanced the release of cytokines and the activation of astrocyte intracellular NF-κB signaling induced by sevoflurane in the hippocampus of adult rats. Blocking NF-κB signaling by pyrrolidine dithiocarbamate (PDTC) inhibited the release of cytokines. MS also reduced the expression of GR and upregulated the methylation levels of the promoter region of GR exon 1₇, and such effects were reversed by treatment with the histone deacetylase inhibitor trichostatin A (TSA) in adult rats. Moreover, TSA treatment in adult MS rats inhibited the overactivation of astrocyte intracellular NF-κB signaling and the release of cytokines and alleviated cognitive dysfunction after sevoflurane anesthesia.

CONCLUSIONS

Early life stress induces cognitive dysfunction after sevoflurane anesthesia, perhaps due to the aberrant methylation of the GR gene promoter, which reduces the expression of the GR gene and facilitates exaggerated inflammatory responses.

Anesthesia specific differences in a cardio-pulmonary resuscitation rat model; halothane versus sevoflurane

OBJECTIVE

Our asphyxia cardiac arrest (ACA) rat model is well established. The original model was designed in the 1990th using halothane and nitrous oxide for pre-insult anesthesia. Because of its hepato-toxicity and its potential to induce severe liver failures, halothane is no longer used in clinical anesthesia for several years. In order to minimize the health risk for our laboratory staff as well as to keep the experimental settings of our model on a clinically oriented basis we decided to replace halothane by sevoflurane. In this study we intended to determine if the change of the narcotic gas regiment causes changes in the neurological damage and how far our model had to be adjusted.

METHODS

Adult rats were subjected to 5min of ACA followed by resuscitation. There were four treatment groups: ACA - halothane, ACA - sevoflurane and with halothane or sevoflurane sham operated animals. Vital and blood parameters were monitored during the 45min post-resuscitation intensive care phase. After a survival time of 7 days histological evaluation of the hippocampus was performed.

RESULTS

We observed that resuscitated rats anesthetized prior by sevoflurane (i) have had a lower heart rate and a higher MAP compared to halothane anesthetized animals; (ii) The neurological damaged were significantly reduced in the hippocampal CA1 region in sevoflurane treated rats.

CONCLUSION

Using sevoflurane instead of halothane for anesthesia requires some physiological and experimental changes. However the model keeps its validity. Sevoflurane caused less pronounced neurodegeneration in the CA1 region of the hippocampus. This had to be considered in further resuscitation-studies containing sevoflurane as anesthetic. Institutional protocol number for animal studies: 42502-2-2-947 Uni MD.

Sevoflurane and isoflurane inhibit KCl-induced Class II phosphoinositide 3-kinase α subunit mediated vasoconstriction in rat aorta

BACKGROUND

Class II phosphoinositide 3-kinase α-isoform (PI3K-C2α) is involved in regulating KCl-induced vascular smooth muscle contraction. The current study was to investigate the effects of sevoflurane (SEVO) and isoflurane (ISO) on KCl-elicited PI3KC2α mediated vasoconstriction in rat aortic smooth muscle.

METHODS

Isometric force, in the absence or presence of SEVO or ISO (1 ~ 3 minimum alveolar concentration, MAC), PI3K inhibitor LY294002, Rho kinase inhibitor Y27632, and membrane translocation of PI3K-p85, PI3K-C2α, Rho kinase (Rock II), or phosphorylation of MYPT1/Thr853, MYPT1/Thr696, CPI-17/Thr38 and MLC in response to KCl (60 mM) was measured by using isometric force transducer and western blotting analysis, respectively.

RESULTS

KCl elicited a rapid and sustained contraction of rat aortic smooth muscle that was inhibited by both SEVO and ISO in a concentration-dependent manner, and also suppressed by LY294002 (1 mM) and Y27632 (1 uM). LY294002 (1 mM) and Y27632 (1 uM) also inhibited KCl-induced MLC phosphorylation. LY294002 (1 mM) inhibited KCl-induced PI3K-p85, PI3K-C2α membrane translocation in response to KCl (p <0.05, p < 0.01, respectively). Not only Y27632 (1 uM), but also LY294002 (1 mM), inhibited KCl-induced Rock-II membrane translocation (p < 0.01). SEVO and ISO inhibited KCl-stimulated MLC phosphorylation, PI3K-C2α and Rock-II,not PI3K p85 membrane translocation in a concentration-dependent manner in rat aorta. Both SEVO and ISO suppressed the MYPT1/Thr853, not MYPT1/Thr696 and CPI-17/Thr38, MLC phosphorylation in response to KCl.

CONCLUSION

PI3K-C2α mediates part of SEVO and ISO-mediated vasodilation in rat aorta. The cellular mechanisms underlying the inhibitory effect of volatile anesthetics might be mediated by KCl/PI3K-C2α/Rho kinase/MYPT1/MLC pathway.

Rats with Chronic, Stable Pulmonary Hypertension Tolerate Low Dose Sevoflurane Inhalation as Well as Normal Rats Do

BACKGROUND

The effects of low concentration of sevoflurane on right ventricular (RV) function and intracellular calcium in the setting of pulmonary arterial hypertension (PAH) have not been investigated clearly. We aim to study these effects and associated signaling pathways in rats with PAH.

METHODS

Hemodynamics were assessed with or without sevoflurane inhalation in established PAH rats. We analysis the classic RV function parameters and RV-PA coupling efficiency using steady-state PV loop recordings. The protein levels of SERCA2, PLB and p-PLB expression was analyzed by western blot to assess their relevance in PAH.

RESULTS

Rats with PAH presented with RV hypertrophy and increased pulmonary arterial pressure. The values of Ea, R/L ratio, ESP, SW, PRSW, +dP/dtmax and the slope of the dP/dtmax-EDV relationship increased significantly in PAH rats (P<0.05). Sevoflurane induced a concentration-dependent decrease of systemic and pulmonary blood pressure, HR, RV contractility, and increased the R/L ratio in both groups. Sevoflurane reduced the expression of SERCA2 and increased the expression of PLB in both groups. Interestingly, sevoflurane only reduced the p-PLB/PLB ratio in PAH rats, not in normal rats.

CONCLUSIONS

Rats with chronic, stable pulmonary hypertension tolerate low concentrations of sevoflurane inhalation as well as normal rats do. It may be related to the modulation of the SERCA2-PLB signaling 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.

The effect of induced hypertension on neurological outcome in forebrain ischaemia model in rats

INTRODUCTION

The present study investigated the effects of induced hypertension on hippocampal cell death after forebrain ischaemia in rats.

MATERIALS AND METHODS

In this study, forebrain ischaemia was induced in 20 Sprague-Dawley rats by clamping the bilateral common carotid arteries to induce systemic hypotension for 8min. All rats then underwent reperfusion during which the induced hypertension group (n=10) received intermittent intravenous injections of phenylephrine (5μg) to maintain their mean arterial blood pressure at 20mmHg above baseline for 10min and the control group (n=10) did not receive any treatment. In both groups, the numbers of viable and apoptotic neuronal cells in the cornu ammonis 1 (CA1) area of the hippocampus were evaluated 7 days after the induction of ischaemia.

RESULTS

The mean percentage of viable neuronal cells was higher in the induced hypertension group than in the control group (35% vs. 26%, respectively; p=0.004), but there was no significant difference in the proportion of apoptotic neuronal cells between the groups (57% vs. 43%, respectively; p=0.165).

CONCLUSIONS

Induced hypertension significantly attenuated necrotic cell death in the hippocampal CA1 area, but apoptotic cell death was not affected.

Arachidonyl-2-Chloroethylamide Alleviates Cerebral Ischemia Injury Through Glycogen Synthase Kinase-3β-Mediated Mitochondrial Biogenesis and Functional Improvement

Arachidonyl-2-chloroethylamide (ACEA), a highly selective agonist of cannabinoid receptor 1 (CB1R), has been reported to protect neurons in ischemic injury. We sought to investigate whether mitochondrial biogenesis was involved in the therapeutic effect of ACEA in cerebral ischemia. Focal cerebral ischemic injury was induced in adult male Sprague Dawley rats. Intraperitoneal injection of 1 mg/kg ACEA improved neurological behavior, reduced infarct volume, and inhibited apoptosis. The volume and numbers of mitochondria were significantly increased after ACEA administration. Expression of mitochondrial transcription factor A (Tfam), nuclear transcription factor-1 (Nrf-1), and cytochrome C oxidase subunit IV (COX IV) were also significantly up-regulated in animals administered ACEA. One thousand nanomoles of ACEA inhibited mitochondrial dysfunction in primary rat cortical neurons exposed to oxygen-glucose deprivation (OGD). Furthermore, ACEA administration increased phosphorylation of glycogen synthase kinase-3β (GSK-3β) after reperfusion. Phosphorylation of GSK-3β induced mitochondrial biogenesis and preserved mitochondrial function whereas inhibition of phosphatidylinositol 3-kinase (PI3K) dampened phosphorylation of GSK-3β and reversed induction of mitochondrial biogenesis and function following ACEA administration. In conclusion, ACEA could induce mitochondrial biogenesis and improve mitochondrial function at the beginning of cerebral ischemia, thus alleviating cerebral ischemia injury. Phosphorylation of GSK-3β might be involved in the regulation of mitochondrial biogenesis induced by ACEA.

Isoflurane Post-Treatment Improves Outcome after an Embolic Stroke in Rabbits

Application of commonly used volatile anesthetics after brain ischemia onset (post-treatment) provides neuroprotection in rodents. To further test its translational potential, this study was designed to determine whether isoflurane post-treatment induced neuroprotection in rabbits after embolic stroke. White male New Zealand rabbits received intra-carotid injection of clots when they were awake. Some rabbits were exposed to 2.5% isoflurane for 1 h at 5 min after the injection. Isoflurane post-treatment increased the tolerance of rabbits to the amount of clots. Isoflurane post-treatment also reduced brain infarct volumes and plasma S100B 3 days after the injection of 5 mg clots and improved neurological deficit scores after the stroke. Isoflurane post-treatment improves neurological outcome in rabbits after embolic stroke.

Sevoflurane postconditioning improves long-term learning and memory of neonatal hypoxia-ischemia brain damage rats via the PI3K/Akt-mPTP pathway

BACKGROUND

Volatile anesthetic postconditioning has been documented to provide neuroprotection in adult animals. Our aim was to investigate whether sevoflurane postconditioning improves long-term learning and memory of neonatal hypoxia-ischemia brain damage (HIBD) rats, and whether the PI3K/Akt pathway and mitochondrial permeability transition pore (mPTP) opening participate in the effect.

METHODS

Seven-day-old Sprague-Dawley rats were subjected to brain HI and randomly allocated to 10 groups (n=24 each group) and treated as follows: (1) Sham, without hypoxia-ischemia; (2) HI/Control, received cerebral hypoxia-ischemia; (3) HI+Atractyloside (Atr), (4) HI+Cyclosporin A (CsA), (5) HI+sevoflurane (Sev), (6) HI+Sev+ LY294002 (LY), (7) HI+Sev+ L-NAME (L-N), (8) HI+Sev+ SB216763 (SB), (9) HI+Sev+Atr, and (10) HI+Sev+CsA. Twelve rats in each group underwent behavioral testing and their brains were harvested for hippocampus neuron count and morphology study. Brains of the other 12 animals were harvested 24h after intervention to examine the expression of Akt, p-Akt, eNOS, p-eNOS, GSK-3β, p-GSK-3β by Western bolting and mPTP opening.

RESULTS

Sevoflurane postconditioning significantly improved the long-term cognitive performance of the rats, increased the number of surviving neurons in CA1 and CA3 hippocampal regions, and protected the histomorphology of the left hippocampus. These effects were abolished by inhibitors of PI3K/eNOS/GSK-3β. Although blocking mPTP opening simulated sevoflurane postconditioning-induced neuroprotection, it failed to enhance it.

CONCLUSIONS

Sevoflurane postconditioning exerts a neuroprotective effect against HIBD in neonatal rats via PI3K/Akt/eNOS and PI3K/Akt/GSK-3β pathways, and blockage of mPTP opening may be involved in attenuation of histomorphological injury.