Propofol Inhibits Lipopolysaccharide-Induced Inflammatory Responses in Spinal Astrocytes via the Toll-Like Receptor 4/MyD88-Dependent Nuclear Factor-κB, Extracellular Signal-Regulated Protein Kinases1/2, and p38 Mitogen-Activated Protein Kinase Pathways

Myelin modulates the process of isoflurane anesthesia through the regulation of neural activity

AIMS

The mechanism underlying the reversible unconsciousness induced by general anesthetics (GA) remains unclear. Recent studies revealed the critical roles of myelin and oligodendrocytes (OLs) in higher functions of the brain. However, it is unknown whether myelin actively participates in the regulation of GA. The aim of this study is to investigate the roles and possible mechanisms of myelin in the regulation of consciousness alterations induced by isoflurane anesthesia.

METHODS

First, demyelination models for the entire brain and specific neural nuclei were established to investigate the potential role of myelination in the regulation of GA, as well as its possible regional specificity. c-Fos staining was then performed on the demyelinated nuclei to verify the impact of myelin loss on neuronal activity. Finally, the activity of neurons during isoflurane anesthesia in demyelinated mice was recorded by optical fiber photometric calcium signal. The related behavioral indicators and EEG were recorded and analyzed.

RESULTS

A prolonged emergence time was observed from isoflurane anesthesia in demyelinated mice, which suggested the involvement of myelin in regulating GA. The demyelination in distinct nuclei by LPC further clarified the region-specific roles of isoflurane anesthesia regulation by myelin. The effect of demyelination on isoflurane anesthesia in the certain nucleus was consistent with that in neurons towards isoflurane anesthesia. Finally, we found that the mechanism of myelin in the modulation of isoflurane anesthesia is possibly through the regulation of neuronal activity.

CONCLUSIONS

In brief, myelin in the distinct neural nucleus plays an essential role in regulating the process of isoflurane anesthesia. The possible mechanism of myelin in the regulation of isoflurane anesthesia is neuronal activity modification by myelin integrity during GA. Our findings enhanced the comprehension of myelin function, and offered a fresh perspective for investigating the neural mechanisms of GA.

General anesthetic agents induce neurotoxicity through astrocytes

ABSTRACT

Neuroscientists have recognized the importance of astrocytes in regulating neurological function and their influence on the release of glial transmitters. Few studies, however, have focused on the effects of general anesthetic agents on neuroglia or astrocytes. Astrocytes can also be an important target of general anesthetic agents as they exert not only sedative, analgesic, and amnesic effects but also mediate general anesthetic-induced neurotoxicity and postoperative cognitive dysfunction. Here, we analyzed recent advances in understanding the mechanism of general anesthetic agents on astrocytes, and found that exposure to general anesthetic agents will destroy the morphology and proliferation of astrocytes, in addition to acting on the receptors on their surface, which not only affect Ca2+ signaling, inhibit the release of brain-derived neurotrophic factor and lactate from astrocytes, but are even involved in the regulation of the pro- and anti-inflammatory processes of astrocytes. These would obviously affect the communication between astrocytes as well as between astrocytes and neighboring neurons, other neuroglia, and vascular cells. In this review, we summarize how general anesthetic agents act on neurons via astrocytes, and explore potential mechanisms of action of general anesthetic agents on the nervous system. We hope that this review will provide a new direction for mitigating the neurotoxicity of general anesthetic agents.

Effect of Total Intravenous Anesthesia on Postoperative Pulmonary Complications in Patients Undergoing Microvascular Reconstruction for Head and Neck Cancer: A Randomized Clinical Trial

Importance

Free flap surgery is a lengthy procedure with massive tissue destruction and reconstruction, which makes postoperative pulmonary complications (PPCs) a noticeable issue among patients with head and neck cancer. Propofol-based total intravenous anesthesia (TIVA) has better survival outcomes than inhalational anesthesia (INH) in several types of cancer surgery. A previous retrospective study found that patients in the TIVA group had a lower PPC rate, which may be correlated with a lower intraoperative fluid requirement. We hypothesize that the protective effect remains among patients undergoing free flap surgery for head and neck cancer in a prospective and goal-directed fluid therapy setting.

Objective

To assess the effect of TIVA vs INH on PPCs in patients undergoing microvascular reconstruction for head and neck cancer.

Design, Setting, and Participants

This prospective, 2-arm, randomized clinical trial was conducted at a tertiary hospital in Taiwan; a total of 78 patients 18 years and older with American Society of Anesthesiologists physical status classification 1 to 3 who were scheduled for elective free flap surgery under general anesthesia were included. The trial started in October 2017, completed in October 2019, and finished analysis in January 2022.

Interventions

Patients were enrolled and randomized to the TIVA or INH group. All patients received goal-directed fluid therapy and hemodynamic management if they had a mean arterial pressure (MAP) below 75 mm Hg or a reduction of 10% from baseline MAP.

Main Outcomes and Measures

The primary outcome was a composite of PPCs. The secondary outcomes were the differences in intraoperative hemodynamic values (mean arterial pressure, MAP; cardiac index, CI; systemic vascular resistance index, SVRI; and stroke volume variation, SVV).

Results

A total of 70 patients (65 men [93%]; 5 women [7%]) completed the trial; median (IQR) age was 52.0 (48-59) years in the TIVA group and 57.0 (46-64) years in the INH group. The demographic characteristics were similar between the 2 groups, except that patients in the TIVA group had a slightly lower body mass index. Patients in the TIVA group had a lower risk of developing PPCs (unadjusted odds ratio, 0.25; 95% CI, 0.08-0.80). The TIVA group had significantly higher MAP, lower CI, and higher SVRI than the INH group after the third hour of monitoring. The TIVA group showed a relatively stable hourly MAP, CI, SVRI, and SVV across time points, while the INH group showed a more varying pattern. The generalized estimating equation showed no clinical differences in the trend of hemodynamic parameters across time between groups.

Conclusions and Relevance

In this randomized clinical trial, using propofol-based TIVA reduced the incidence of PPCs in free flap surgery. This finding may be related to more stable hemodynamic manifestations and a lower total balance of fluid throughout the surgery.

Trial Registration

ClinicalTrials.gov Identifier: NCT03263078.

High-fat diet and alcohol induced-mice could cause colonic injury through molecular mechanisms of endogenous toxins

Due to the complexity and diverse causes, the pathological mechanism of diet-induced colonic injury and colitis remains unclear. In this study, we studied the effects of the combination of a high-fat diet (HFD) plus alcohol on colonic injury in mice. We found HFD plus alcohol treatment induced disturbance of the gut microbiota; increased the production of intestinal toxins lipopolysaccharide (LPS), indole, and skatole; destroyed the stability of the intestinal mucosa; and caused the colonic epithelial cells damage through the activation of nuclear factor (NF)-κB and aromatic hydrocarbon receptors (AhR) signaling pathways. To mimic the effect of HFD plus alcohol in vivo, NCM460 cells were stimulated with alcohol and oleic acid with/without intestinal toxins (LPS, indole, and skatole) in vitro. Combinative treatment of alcohol and oleic acid caused moderate damage on NCM460 cells, while combination with intestinal toxins induced serious cell apoptosis. Western blot data indicated that the activation of NF-κB and AhR pathways further augmented after intestinal toxins treatment in alcohol- and oleic acid-treated colonic cells. This study provided new evidence for the relationship between diet pattern and colonic inflammation, which might partly reveal the pathological development of diet-induced colon disease and the involvement of intestinal toxins.

Toll-like receptor 4 activation enhances Orai1-mediated calcium signal promoting cytokine production in spinal astrocytes

Toll-like receptor 4 (TLR4) has been implicated in pathological conditions including chronic pain. Activation of astrocytic TLRs leads to the synthesis of pro-inflammatory cytokines like interleukin 6 (IL-6) and tumor necrosis factor-ɑ (TNF-α), which can cause pathological inflammation and tissue damage in the central nervous system. However, the mechanisms of TLR4-mediated cytokine releases from astrocytes are incomplete understood. Our previous study has shown that Orai1, a key component of calcium release activated calcium channels (CRACs), mediates Ca²⁺ entry in astrocytes. How Orai1 contributes to TLR4 signaling remains unclear. Here we show that Orai1 deficiency drastically attenuated lipopolysaccharides (LPS)-induced TNF-α and IL-6 production in astrocytes. Acute LPS treatment did not induce Ca²⁺ response and had no effect on thapsigargin (Ca²⁺-ATPase inhibitor)-induced store-dependent Ca²⁺ entry. Inhibition or knockdown of Orai1 showed no reduction in LPS-induced p-ERK1/2, p-c-Jun N-terminal kinase, or p-p38 MAPK activation. Interestingly, Orai1 protein level was significantly increased after LPS exposure, which was blocked by inhibition of NF-κB activity. LPS significantly increased basal Ca²⁺ level and SOCE after exposure to astrocytes. Moreover, elevating extracellular Ca²⁺ concentration increased cytosolic Ca²⁺ level, which was almost eliminated in Orai1 KO astrocytes. Our study reports novel findings that Orai1 acts as a Ca²⁺ leak channel regulating the basal Ca²⁺ level and enhancing cytokine production in astrocytes under the inflammatory condition. These findings highlight an important role of Orai1 in astrocytic TRL4 function and may suggest that Orai1 could be a potential therapeutic target for neuroinflammatory disorders including chronic pain.

Propofol ameliorates ischemic brain injury by blocking TLR4 pathway in mice

Ischemic brain injury is one of the most serious perioperative complications. However, effective preventative methods have not yet been established. This study aimed to investigate whether propofol has neuroprotective effects against ischemic brain injury, with a specific focus on Toll-like receptor 4 (TLR4). Focal brain ischemia was induced via a combination of left common carotid artery occlusion and distal left middle cerebral artery coagulation in mice. Either propofol (10 mg/kg) or vehicle was intravenously injected 10 min prior to the induction of brain ischemia in wild-type and TLR4 knockout mice. Infarct volume, pro-inflammatory cytokine expression, inflammatory cell infiltration, and neurobehavioral function were assessed. Propofol administration significantly reduced infarct volume in wild-type mice (26.9 ± 2.7 vs 15.7 ± 2.0 mm³ at day 7), but not in TLR4 knockout mice. Compared with the control mice, the propofol-treated wild-type mice exhibited lower levels of IL-6 (0.57 ± 0.23 vs 1.00 ± 0.39 at 24 h), and smaller numbers of TLR4-expressing microglia in the penumbra (11.7 ± 3.1 vs 25.1 ± 4.7 cells/0.1 mm²). In conclusion, propofol administration prior to ischemic brain insult attenuated brain injury by blocking the TLR4-dependent pathway and suppressing pro-inflammatory cytokine production.

Neuroprotective and anti-inflammatory effect of pectolinarigenin, a flavonoid from Amazonian Aegiphila integrifolia (Jacq.), against lipopolysaccharide-induced inflammation in astrocytes via NFκB and MAPK pathways

Neurodegenerative diseases affect millions of people worldwide. Regardless of the underlying cause, neuroinflammation is the greatest risk factor for developing any of these disorders. Pectolinarigenin (PNG) is an active flavonoid with several biological properties, anti-metastatic and anti-inflammatory activity. This study investigate the biological effects of PNG in macrophage and astrocyte cultures, with focus on elucidating the molecular mechanisms involved in the PNG activity. J774A.1 murine macrophage or cerebral cortex primary astrocytes primary cultures were treated with different concentration of PNG (1-160 μM) and the inflammatory process was stimulated by LPS (1 μg/ml) and the effect of PNG in different inflammatory markers were determined. PNG did not affect astrocyte or macrophage viability. Moreover, this flavonoid reduced NO• release in macrophages, attenuated astrocyte activation by preventing the overexpression of glial fibrillary acidic protein, and decreased the release of inflammatory mediators, IL-1β and IL-6 induced by LPS by the glial cell, as well as enhanced basal levels of IL-10. In addition, PNG suppressed NFκB, p38MAPK and ERK1/2 phosphorylation in astrocytes culture induced by LPS. The results show clear evidence that this novel flavonoid protects astrocytes against LPS-induced inflammatory toxicity. In conclusion, PNG presents neuroprotective and anti-inflammatory property through the inhibition of inflammatory signaling pathways.

Knockdown of long non-coding RNA NEAT1 relieves the inflammatory response of spinal cord injury through targeting miR-211-5p/MAPK1 axis

Spinal cord injury (SCI) is a refractory disease often accompanied by inflammation. Long non-coding RNA NEAT1 (lncRNA NEAT1) was reported to be involved in the expression of the inflammasomes, while the regulatory effect of NEAT1 on SCI was poorly investigated. Herein, we carried out further studies on the pathogenesis of SCI. PC-12 cells were incubated with lipopolysaccharide (LPS) to induce inflammation. Western blotting assay was used to measure the protein expression levels. RNA expression levels were analyzed using RT-qPCR. Cell counting kit 8 and flow cytometry assays were used to separately determine the cell viability and apoptosis rate. The targeted relationships were verified by luciferase reporter and RNA pull-down assays. It was found that LPS induced inflammation in the PC-12 cells, leading to significantly higher cell apoptosis rate and lower viability, and the expression level of NEAT1 was elevated by LPS. However, knockdown of NEAT1 partially reversed the effects of LPS. Subsequently, the potential interaction between NEAT1 and miR-211-5p was validated and miR-211-5p inhibitor was further confirmed to antagonize the effects of NEAT knockdown. The downstream target gene of miR-211-5p was predicted and verified to be MAPK1. In addition, overexpression of MAPK1 was proved to antagonize the effects of NEAT1 knockdown. Taken together, the knockdown of NEAT1 remarkably alleviated the inflammation of SCI via miR-211-5p/MAPK1 axis.

Ginkgo diterpene lactones inhibit cerebral ischemia/reperfusion induced inflammatory response in astrocytes via TLR4/NF-κB pathway in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgo biloba L. (Ginkgoaceae) is a traditional Chinese medicine known to treating stroke and other cardio-cerebrovascular diseases for thousands of years in China. Ginkgo diterpene lactones (GDL) attracted much attention because of their neuroprotective properties.

AIM OF THE STUDY

To uncover the effects of GDL, which consist of ginkgolide A (GA), ginkgolide B (GB), and ginkgolide K (GK), on ischemic stroke, as well as the underlying molecular mechanisms.

MATERIALS AND METHODS

We used middle cerebral artery occlusion/reperfusion (MCAO/R) and oxygen-glucose deprivation/reoxygenation (OGD/R) models mimicking the process of ischemia/reperfusion in vivo and in vitro, respectively. Anticoagulant effects of GDL were investigated on platelet activating factor (PAF), arachidonic acid (AA) and adenosine diphosphate (ADP)-induced platelet aggregation both in vivo and in vitro. We also evaluated the effects of GDL on lipopolysaccharide (LPS)-induced inflammatory response in primary cultured rats' astrocytes. Infarct size, neurological deficit score, and brain edema were measured at 72 h after MCAO. Immunohistochemistry was utilized to analyze neurons necrosis and astrocytes activation. Expression of pro-inflammatory cytokines, including tumor necrotic factor-α (TNF-α) and interleukin-1β (IL-1β) were detected using enzyme-linked immunosorbent assay (ELISA) and real time PCR. The levels of toll-like receptor 4 (TLR4) and nuclear factor κB (NF-κB) were assessed by real time PCR or Western blot.

RESULTS

Compared with MCAO/R rats, GDL significantly reduced infarct size and brain edema, improved neurological deficit score. Meanwhile, GDL suppressed platelet aggregation, astrocytes activation, pro-inflammatory cytokines releasing, TLR4 mRNA expression and transfer of NF-κB from cytoplasm to nucleus. Furthermore, GDL alleviated OGD/R injury and LPS-induced inflammatory response in primary astrocytes, characterized by promoting cell viability, decreasing lactate dehydrogenase (LDH) activity, and inhibiting IL-1β and TNF-α releasing.

CONCLUSIONS

In summary, GDL attenuate cerebral ischemic injury, inhibit platelet aggregation and astrocytes activation. The anti-inflammatory activity might be associated with the downregulation of TLR4/NF-κB signal pathway. Our present findings provide an innovative insight into the novel treatment of GDL in ischemic stroke therapy.

Pain management in living related adult donor hepatectomy: feasibility of an evidence-based protocol in 100 consecutive donors

Objective

Living donor hepatectomy (LDH) has important consequences in terms of acute and chronic pain. We proposed an anesthetic protocol based on the best currently available evidence. We report the results of this protocol’s application.

Results

We performed a retrospective descriptive study of 100 consecutive donors undergoing LDH. The protocol included standardized information provided by the anesthetist, pharmacological anxiolysis and preventive analgesia. Specifically, pregabalin premedication (opioid-free) intravenous anesthesia (with clonidine, ketamine, magnesium sulphate and ketorolac) and epidural analgesia were proposed. Postoperative follow-up was conducted by the Postoperative Pain Service. This analysis included 100 patients (53 women, 47 men, median age 32.7 years old [28.4–37.3]), operated by xypho-umbilical laparotomy. All elements of our anesthetic protocol were applied in over 75% of patients, except for the preoperative consultation with a senior anesthesiologist (55%). The median number of applied item was 7 [interquartile range, IQR 5–7]. Median postoperative pain scores were, at rest and at mobilization respectively 3 [IQR 2–4] and 6 [IQR 4.5–7] on day 1; 2 [IQR 1–3] and 5 [IQR 3–6] on day 2; and 2 [IQR 0–3] and 4 [IQR 3–5] on day 3. In conclusion, LDH leads to severe acute pain. Despite the proposal of a multimodal evidence-based protocol, its applicancy was not uniform and the pain scores remained relatively high.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3941-1) contains supplementary material, which is available to authorized users.

Z-Guggulsterone attenuates astrocytes-mediated neuroinflammation after ischemia by inhibiting toll-like receptor 4 pathway

Inflammatory damage plays a pivotal role in ischemic stroke pathogenesis and may represent one of the therapeutic targets. Z-Guggulsterone (Z-GS), an active component derived from myrrh, has been used to treat various diseases. The traditional uses suggest that myrrh is a good candidate for anti-inflammatory damage. This study was to investigate the anti-inflammatory and neuroprotective effects of Z-GS following cerebral ischemic injury, as well as the exact mechanisms behind them. Rat middle cerebral artery occlusion (MCAO) model and in vitro astrocytes oxygen-glucose deprivation (OGD) model were adopted to simulate ischemic stroke. Z-GS (30 or 60 mg/kg) was administered intraperitoneally immediately after reperfusion, while astrocytes were maintained in 30 or 60 μM Z-GS before OGD treatment. The results indicated that Z-GS significantly alleviated neurological deficits, infarct volume and histopathological damage in vivo, and increased the astrocytes viability in vitro. Moreover, the treatment of Z-GS inhibited the astrocytes activation and down-regulated the mRNA levels of pro-inflammatory cytokines. Furthermore, the activated TLR4-NF-κB signaling pathways induced by MCAO or OGD were significantly suppressed by Z-GS treatment, which was achieved via inhibiting the phosphorylation of JNK. Our results demonstrated that Z-GS exerted neuroprotective and anti-inflammatory properties through preventing activation of TLR4-mediated pathway in the activated astrocytes after ischemia injury. Therefore, Z-GS could be considered as a promising candidate for the treatment of ischemic stroke.

MicroRNA‑214 suppresses propofol‑induced neuroapoptosis through activation of phosphoinositide 3‑kinase/protein kinase B signaling by targeting phosphatase and tensin homolog expression

The present study aimed to investigate the effects of microRNA (miR)‑214 on neuroapoptosis induced by propofol and the possible mechanism of its anti‑apoptotic effects. Initially, it was observed that miR‑214 expression was upregulated in propofol‑induced neuroapoptosis rats. Next, propofol‑treated nerve cells were transfected with miR‑214 mimics. The results revealed that miR‑214 overexpression induced apoptosis, inhibited cell proliferation, inhibited cyclin D1 protein expression, promoted caspase‑3 activity and B‑cell lymphoma 2‑associated X protein expression, and enhanced the levels of inflammation factors in nerve cells treated with propofol. In addition, miR‑214 overexpression suppressed phosphoinositide 3‑kinase/protein kinase B (PI3K/Akt) signaling by targeting the activation of phosphatase and tensin homolog (PTEN) and nuclear factor‑κB expression in nerve cells treated with propofol. Treatment with a PTEN inhibitor successfully suppressed the PTEN protein expression and decreased the apoptosis of propofol‑treated nerve cells subsequent to miR‑214 overexpression through PI3K/Akt signaling. In conclusion, the present study data revealed that miR‑214 suppressed propofol‑induced neuroapoptosis through the activation of PI3K/Akt signaling by targeting PTEN expression.

Propofol Attenuates Airway Inflammation in a Mast Cell-Dependent Mouse Model of Allergic Asthma by Inhibiting the Toll-like Receptor 4/Reactive Oxygen Species/Nuclear Factor κB Signaling Pathway

Propofol, an intravenous anesthetic agent widely used in clinical practice, is the preferred anesthetic for asthmatic patients. This study was designed to determine the protective effect and underlying mechanisms of propofol on airway inflammation in a mast cell-dependent mouse model of allergic asthma. Mice were sensitized by ovalbumin (OVA) without alum and challenged with OVA three times. Propofol was given intraperitoneally 0.5 h prior to OVA challenge. The inflammatory cell count and production of cytokines in the bronchoalveolar lavage fluid (BALF) were detected. The changes of lung histology and key molecules of the toll-like receptor 4 (TLR4)/reactive oxygen species (ROS)/NF-κB signaling pathway were also measured. The results showed that propofol significantly decreased the number of eosinophils and the levels of IL-4, IL-5, IL-6, IL-13, and TNF-α in BALF. Furthermore, propofol significantly attenuated airway inflammation, as characterized by fewer infiltrating inflammatory cells and decreased mucus production and goblet cell hyperplasia. Meanwhile, the expression of TLR4, and its downstream signaling adaptor molecules--myeloid differentiation factor 88 (MyD88) and NF-κB, were inhibited by propofol. The hydrogen peroxide and methane dicarboxylic aldehyde levels were decreased by propofol, and the superoxide dismutase activity was increased in propofol treatment group. These findings indicate that propofol may attenuate airway inflammation by inhibiting the TLR4/MyD88/ROS/NF-κB signaling pathway in a mast cell-dependent mouse model of allergic asthma.

Up-regulation of TNF Receptor-associated Factor 7 after spinal cord injury in rats may have implication for neuronal apoptosis

TNF receptor-associated factor 7 (TRAF7), is an E3 ubiquitin ligase for several proteins involved in the activation of TLR-dependent NF-kappaB signaling. TRAF7 links TNF receptor family proteins to signaling pathways, thus participates in regulating cell death and survival mediated by TNF family ligands. To date, the biological function of TRAF7 after spinal cord injury (SCI) is still with limited acquaintance. In this study, we have performed an acute SCI model in adult rats and investigated the dynamic changes of TRAF7 expression in the spinal cord. Our results showed that TRAF7 was up-regulated significantly after SCI, which was paralleled with the levels of the apoptotic protein active caspase-3. Immunofluorescent labeling showed that TRAF7 was co-localizated with active caspase-3 in neurons. To further investigate the function of TRAF7, an apoptosis model was established in primary neuronal cells. When TRAF7 was knocked down by specific short interfering RNA (siRNA), the protein levels of active caspase-3 and the number of apoptotic primary neurons were significantly decreased in our study. Taken together, our findings suggest that the change of TRAF7 protein expression plays a key role in neuronal apoptosis after SCI.

Propofol inhibits NF-κB activation to ameliorate airway inflammation in ovalbumin (OVA)-induced allergic asthma mice

Propofol, one of the most commonly used intravenous anesthetic agents, has been reported to have anti-inflammatory property. However, the anti-allergic inflammation effect of propofol and its underlying molecular mechanisms have not been elucidated. In the present study, we aim to investigate the roles of NF-kB activation in propofol anti-asthma effect on OVA-induced allergic airway inflammation in mice. In a standard experimental asthma model, Balb/c mice were sensitized with ovalbumin, treated with propofol (50,100,150mg/kg) or a vehicle control 1h before OVA challenge. Blood samples, bronchoalveolar lavage fluid (BALF) and lung tissues were harvested after measurement of airway hyperresponsiveness. Results revealed that propofol not only significantly inhibit airway hyperresponsiveness, but also inhibited the production of Th2 cytokines, NO, Ova-specific IgE and eotaxin. Histological studies indicated that propofol significantly attenuated OVA-induced inflammatory cell infiltration in the peribronchial areas and mucus hypersecretion. Meanwhile, our results indicated that propofol was found to inhibit NF-kB activation in OVA-Induced mice. Furthermore, propofol significantly reduced the TNF-α-induced NF-kB activation in A549 cells. In conclusion, our study suggested that propofol effectively reduced allergic airway inflammation by inhibiting NF-kB activation and could thus be used as a therapy for allergic asthma.

Intracellular Ca2+ homeostasis and JAK1/STAT3 pathway are involved in the protective effect of propofol on BV2 microglia against hypoxia-induced inflammation and apoptosis

BACKGROUND

Perioperative hypoxia may induce microglial inflammation and apoptosis, resulting in brain injury. The neuroprotective effect of propofol against hypoxia has been reported, but the underlying mechanisms are far from clear. In this study, we explored whether and how propofol could attenuate microglia BV2 cells from CoCl2-induced hypoxic injury.

METHODS

Mouse microglia BV2 cells were pretreated with propofol, and then stimulated with CoCl2. TNF-α level in the culture medium was measured by ELISA kit. Cell apoptosis and intracellular calcium concentration were measured by flow cytometry analysis. The effect of propofol on CoCl2-modulated expression of Ca2+/Calmodulin (CaM)-dependent protein kinase II (CAMKIIα), phosphorylated CAMKIIα (pCAMKIIα), STAT3, pSTAT3Y705, pSTAT3S727, ERK1/2, pERK1/2, pNFκB(p65), pro-caspase3, cleaved caspase 3, JAK1, pJAK1, JAK2, pJAK2 were detected by Western blot.

RESULTS

In BV2 cell, CoCl2 treatment time-dependently increased TNF-α release and induced apoptosis, which were alleviated by propofol. CoCl2 (500μmol/L, 8h) treatment increased intracellular Ca2+ level, and caused the phosphorylation of CAMKIIα, ERK1/2 and NFκB (p65), as well as the activation of caspase 3. More importantly, these effects could be modulated by 25μmol/L propofol via maintaining intracellular Ca2+ homeostasis and via up-regulating the phosphorylation of JAK1 and STAT3 at Tyr705.

CONCLUSION

Propofol could protect BV2 microglia from hypoxia-induced inflammation and apoptosis. The potential mechanisms may involve the maintaining of intracellular Ca2+ homeostasis and the activation of JAK1/STAT3 pathway.

General anesthetics have differential inhibitory effects on gap junction channels and hemichannels in astrocytes and neurons

Astrocytes represent a major non-neuronal cell population actively involved in brain functions and pathologies. They express a large amount of gap junction proteins that allow communication between adjacent glial cells and the formation of glial networks. In addition, these membrane proteins can also operate as hemichannels, through which "gliotransmitters" are released, and thus contribute to neuroglial interaction. There are now reports demonstrating that alterations of astroglial gap junction communication and/or hemichannel activity impact neuronal and synaptic activity. Two decades ago we reported that several general anesthetics inhibited gap junctions in primary cultures of astrocytes (Mantz et al., (1993) Anesthesiology 78(5):892-901). As there are increasing studies investigating neuroglial interactions in anesthetized mice, we here updated this previous study by employing acute cortical slices and by characterizing the effects of general anesthetics on both astroglial gap junctions and hemichannels. As hemichannel activity is not detected in cortical astrocytes under basal conditions, we treated acute slices with the endotoxin LPS or proinflammatory cytokines to induce hemichannel activity in astrocytes, which in turn activated neuronal hemichannels. We studied two extensively used anesthetics, propofol and ketamine, and the more recently developed dexmedetomidine. We report that these drugs have differential inhibitory effects on gap junctional communication and hemichannel activity in astrocytes when used in their respective, clinically relevant concentrations, and that dexmedetomidine appears to be the least effective on both channel functions. In addition, the three anesthetics have similar effects on neuronal hemichannels. Altogether, our observations may contribute to optimizing the selection of anesthetics for in vivo animal studies.