Propofol reduces inflammatory reaction and ischemic brain damage in cerebral ischemia in rats

Solid lipid nanoparticle: A potent vehicle of the kaempferol for brain delivery through the blood-brain barrier in the focal cerebral ischemic rat

Kaempferol is major flavonoid present in Convolvulus pluricaulis. This phytochemical protects the brain against oxidative stress, neuro-inflammation, neurotoxicity, neurodegeneration and cerebral ischemia induced neuronal destruction. Kaempferol is poorly water soluble. Our study proved that solid lipid nanoparticles (SLNs) were efficient carrier of kaempferol through blood-brain barrier (BBB). Kaempferol was incorporated into SLNs prepared from stearic acid with polysorbate 80 by the process of ultrasonication. Mean particle size and zeta potential of kaempferol loaded solid lipid nanoparticles (K-SLNs) were 451.2 nm and -15.0 mV. Atomic force microscopy showed that K-SLNs were spherical in shape. Fourier transformed infrared microscopy (FTIR) showed that both stearic acid and kaempferol were present in K-SLNs. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) revealed that the matrices of K-SLNs were in untidy crystalline state. Entraptment efficiency of K-SLNs was 84.92%. In-vitro drug release percentage was 93.24%. Kaempferol loaded solid lipid nanoparticles (K-SLNs) showed controlled release profile. In-vitro uptake study showed significant efficiency of K-SLNs to cross blood-brain barrier (BBB). After oral administration into the focal cerebral ischemic rat, accumulation of fluorescent labeled K-SLNs was observed in the brain cortex which confirmed its penetrability into the brain. It significantly decreased the neurological deficit, infarct volume and level of reactive oxygen species (ROS) and decreased the level of pro-inflammatory mediators like NF-κB and p-STAT3. Damaged neurons and brain texture were improved. This study indicated increased bioavailability of kaempferol into the brain tissue through SLNs formulation.

Mild hypothermia combined with dexmedetomidine reduced brain, lung, and kidney damage in experimental acute focal ischemic stroke

BACKGROUND

Sedatives and mild hypothermia alone may yield neuroprotective effects in acute ischemic stroke (AIS). However, the impact of this combination is still under investigation. We compared the effects of the combination of mild hypothermia or normothermia with propofol or dexmedetomidine on brain, lung, and kidney in experimental AIS. AIS-induced Wistar rats (n = 30) were randomly assigned, after 24 h, to normothermia or mild hypothermia (32-35 °C) with propofol or dexmedetomidine. Histologic injury score and molecular biomarkers were evaluated not only in brain, but also in lung and kidney. Hemodynamics, ventilatory parameters, and carotid Doppler ultrasonography were analyzed for 60 min.

RESULTS

In brain: (1) hypothermia compared to normothermia, regardless of sedative, decreased tumor necrosis factor (TNF)-α expression and histologic injury score; (2) normothermia + dexmedetomidine reduced TNF-α and histologic injury score compared to normothermia + propofol; (3) hypothermia + dexmedetomidine increased zonula occludens-1 expression compared to normothermia + dexmedetomidine. In lungs: (1) hypothermia + propofol compared to normothermia + propofol reduced TNF-α and histologic injury score; (2) hypothermia + dexmedetomidine compared to normothermia + dexmedetomidine reduced histologic injury score. In kidneys: (1) hypothermia + dexmedetomidine compared to normothermia + dexmedetomidine decreased syndecan expression and histologic injury score; (2) hypothermia + dexmedetomidine compared to hypothermia + propofol decreased histologic injury score.

CONCLUSIONS

In experimental AIS, the combination of mild hypothermia with dexmedetomidine reduced brain, lung, and kidney damage.

Enhanced hippocampal neurogenesis mediated by PGC-1α-activated OXPHOS after neonatal low-dose Propofol exposure

Background

Developing brain is highly plastic and can be easily affected. Growing pediatric usage of anesthetics during painless procedures has raised concerns about the effect of low-dose anesthetics on neurodevelopment. It is urgent to ascertain the neuronal effect of low-dose Propofol, a widely used anesthetic in pediatrics, on developing brains.

Methods

The behavioral tests after neonatal exposure to low-dose/high-dose Propofol in mice were conducted to clarify the cognitive effect. The nascent cells undergoing proliferation and differentiation stage in the hippocampus and cultured neural stem cells (NSCs) were further identified. In addition, single-nuclei RNA sequencing (snRNA-seq), NSCs bulk RNA-seq, and metabolism trials were performed for pathway investigation. Furthermore, small interfering RNA and stereotactic adenovirus injection were, respectively, used in NSCs and hippocampal to confirm the underlying mechanism.

Results

Behavioral tests in mice showed enhanced spatial cognitive ability after being exposed to low-dose Propofol. Activated neurogenesis was observed both in hippocampal and cultured NSCs. Moreover, transcriptome analysis of snRNA-seq, bulk RNA-seq, and metabolism trials revealed a significantly enhanced oxidative phosphorylation (OXPHOS) level in NSCs. Furthermore, PGC-1α, a master regulator in mitochondria metabolism, was found upregulated after Propofol exposure both in vivo and in vitro. Importantly, downregulation of PGC-1α remarkably prevented the effects of low-dose Propofol in activating OXPHOS and neurogenesis.

Conclusions

Taken together, this study demonstrates a novel alteration of mitochondrial function in hippocampal neurogenesis after low-dose Propofol exposure, suggesting the safety, even potentially beneficial effect, of low-dose Propofol in pediatric use.

Non-mitogenic fibroblast growth factor 1 protects against ischemic stroke by regulating microglia/macrophage polarization through Nrf2 and NF-κB pathways

Microglia are immune cells in the central nervous system (CNS) that participate in response to pathological process after ischemic injury. Non-mitogenic fibroblast growth factor 1 (nmFGF1) is an effective neuroprotective factor that is also known as a metabolic regulator. The present study aimed to investigate the effects and mechanism of the neuroprotective ability of nmFGF1 on microglia in mice after photothrombosis (PT) stroke model, to determine whether it could ameliorate ischemic injury in stroke experiment. We discovered that the intranasal administration of nmFGF1 reduced infarct size and ameliorated neurological deficits in behavioral assessment by regulating the secretion of proinflammatory and anti-inflammatory cytokines. Furthermore, in the in vitro experiments, we found that nmFGF1 regulated the expression levels of proinflammatory and anti-inflammatory cytokines in oxygen-glucose deprivation (OGD) and lipopolysaccharide (LPS) stimulation. Evidence have shown that when nuclear factor erythroid 2-related factor 2 (Nfr2) is activated, it inhibits nuclear factor-kappa B (NF-κB) activation to alleviate inflammation. Interestingly, nmFGF1 treatment in vivo remarkably inhibited NF-κB pathway activation and activated Nrf2 pathway. In addition, nmFGF1 and NF-κB inhibitor (BAY11-7082) inhibited NF-κB pathway in LPS-stimulated BV2 microglia. Moreover, in LPS-stimulated BV2 microglia, the anti-inflammatory effect produced by nmFGF1 was knocked down by Nrf2 siRNA. These results indicate that nmFGF1 promoted functional recovery in experimental stroke by modulating microglia/macrophage-mediated neuroinflammation via Nrf2 and NF-κB signaling pathways, making nmFGF1 a potential agent against ischemic stroke.

Propofol rescued astrocytes from LPS-induced inflammatory response via blocking LncRNA-MEG3/NF-κB axis

OBJECTIVE

Evidences had demonstrated that propofol attenuated neuro-inflammation following brain ischemia. Moreover, LncRNA-MEG3 was identified as an independent prognostic marker for ischemic stroke patients, and was found to be correlated with cerebral ischemia in animal models. Therefore, the current study explored the role of propofol on lipopolysaccharide (LPS)-mediated inflammation in cultured astrocytes, along with the molecular mechanism involved in LncRNA-MEG3/NF-κB axis.

METHODS

The primary cultured astrocytes isolated from rats were used to establish an inflammatory model, which were treated with LPS. Propofol was administrated to the primary cultured astrocytes during LPS treatment. The effect of propofol on pro-inflammatory cytokines and the LncRNA-MEG3/NF-κB pathway were detected by ELISA, qRT-PCR and Western Blot assay, respectively. Then, dual-luciferase assay, chromatin immunoprecipitation and RNA immunoprecipitation were used to determine the interaction between LncRNA-MEG3 and NF-κB.

RESULTS

Our study found that propofol significantly reduced LncRNA-MEG3 expression, which was elevated in LPS-stimulated astrocytes. Moreover, both propofol and LncRNA-MEG3 knockdown remarkably alleviated LPS-induced cytotoxicity by suppressing expressions and release of pro-inflammatory cytokines. Loss of LncRNA-MEG3 notably suppressed the NF-κB activity and its phosphorylated activation. Additionally, it was also observed that LncRNA-MEG3 could bind nuclear p65/p50, and promote the binding of NF-κB to IL-6 and TNF-α promoters in the nucleus, subsequently stimulating the production of inflammatory cytokines in LPS-treated astrocytes. Furthermore, a specific inhibitor of NF-κB, PDTC rescued astrocytes from LPS exposure without affecting LncRNA-MEG3 expression.

CONCLUSION

These findings demonstrated that LncRNA-MEG3 acted as a positive regulator of NF-κB, mediated the neuroprotection of propofol in LPS-triggered astrocytes injury.

Schisandrin B Inhibits NLRP3 Inflammasome Pathway and Attenuates Early Brain Injury in Rats of Subarachnoid Hemorrhage

OBJECTIVE

To determine whether Schisandrin B (Sch B) attenuates early brain injury (EBI) in rats with subarachnoid hemorrhage (SAH).

METHODS

Sprague-Dawley rats were divided into sham (sham operation), SAH, SAH+vehicle, and SAH+Sch B groups using a random number table. Rats underwent SAH by endovascular perforation and received Sch B (100 mg/kg) or normal saline after 2 and 12 h of SAH. SAH grading, neurological scores, brain water content, Evan's blue extravasation, and terminal transferase-mediated dUTP nick end-labeling (TUNEL) staining were carried out 24 h after SAH. Immunofluorescent staining was performed to detect the expressions of ionized calcium binding adapter molecule 1 (Iba-1) and myeloperoxidase (MPO) in the rat brain, while the expressions of B-cell lymphoma 2 (Bcl-2), Bax, Caspase-3, nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3), apoptosis-associated specklike protein containing the caspase-1 activator domain (ASC), Caspase-1, interleukin (IL)-1β, and IL-18 in the rat brains were detected by Western blot.

RESULTS

Compared with the SAH group, Sch B significantly improved the neurological function, reduced brain water content, Evan's blue content, and apoptotic cells number in the brain of rats (P<0.05 or P<0.01). Moreover, Sch B decreased SAH-induced expressions of Iba-1 and MPO (P<0.01). SAH caused the elevated expressions of Bax, Caspase-3, NLRP3, ASC, Caspase-1, IL-1β, and IL-18 in the rat brain (P<0.01), all of which were inhibited by Sch B (P<0.01). In addition, Sch B increased the Bcl-2 expression (P<0.01).

CONCLUSION

Sch B attenuated SAH-induced EBI, which might be associated with the inhibition of neuroinflammation, neuronal apoptosis, and the NLRP3 inflammatory signaling pathway.

Effects of Txk‑mediated activation of NF‑κB signaling pathway on neurological deficit and oxidative stress after ischemia‑reperfusion in rats

Ischemic stroke is an extremely mortal cerebrovascular disease, and neuroinflammation and oxidative stress emerge as important traits of ischemic stroke. However, as an inflammation‑associated factor, Txk tyrosine kinases (Txk) has been poorly studied in neuroscience research. The aim of the present study was to investigate the role of Txk after ischemia‑reperfusion (I/R) in vivo and in vitro, observe the association between Txk knockdown and neurological deficit and oxidative stress, and to explore whether the process was mediated by the activation of nuclear factor (NF)‑κB signaling pathway. Middle cerebral artery occlusion (MCAO), oxygen and glucose deprivation/reperfusion (OGD/R) model and western blotting have been used to simulate the I/R injury to analyze the expression, and to approximate the localization of Txk, respectively. Brain infarct volume, neurological score, brain water content, apoptosis and oxidative stress assays in vivo and apoptosis, cellular viability, the LDH release and oxidative stress assays in vitro were observed using a Txk‑knockdown lentivirus. Finally, NF‑κB overexpression lentivirus was applied to discuss whether the role of Txk following I/R was regulated by the NF‑κB signaling pathway. The results show that the Txk expression peaked at 24 h after MCAO and 6 h after OGD/R, respectively. Txk molecules gradually entered the nucleus after MCAO and OGD/R. The Txk‑knockdown lentivirus resulted in decreased brain infarct volume, neurological score, brain water content, apoptosis and oxidative stress after MCAO in vivo. Besides, Txk knockdown decreased apoptosis, LDH release, oxidative stress, and increased cellular viability, after ODG in vitro. Finally, NF‑κB overexpression reversed the process of neurological deficit and oxidative stress after Txk regulation in vivo and vitro. Overall, the present study suggests that Txk potentially regulates apoptosis, neurological deficit, and oxidative stress after I/R, by entering the nucleus. NF‑κB maybe the downstream target factor of Txk.

Tectorigenin attenuates the OGD/R-induced HT-22 cell damage through regulation of the PI3K/AKT and the PPARγ/NF-κB pathways

Tectorigenin (TEC) is an effective compound that derived from many plants, such as Iris unguicularis, Belamcanda chinensis and Pueraria thunbergiana Benth. Evidence suggested that TEC has anti-tumor, anti-oxidant activity, anti-bacterial and anti-inflammatory effects. In addition, there has some evidence indicated that TEC is a potential anti-stroke compound; however, its specific roles and associated mechanism have not yet been elucidated. In the present study, we aimed to investigate the anti-inflammatory, anti-oxidant activity and anti-apoptosis effects of TEC on oxygen-glucose deprivation/reperfusion (OGD/R)-induced HT-22 cells, and clarified the relevant mechanisms. Here, we observed that TEC significantly promoted cell survival, impeded cell apoptosis, inhibited ROS and inflammatory cytokines IL-1β, IL-6, TNF-α production in OGD/R-induced HT-22 cells. Moreover, TEC activated PI3K/AKT signal pathway, increased PPARγ expression and inhibited NF-κB pathway activation in OGD/R-induced HT-22 cells. Further studies indicated that PPARγ inhibitor GW9662 activated NF-κB pathway after TEC treatment in OGD/R-induced HT-22 cells. Also, PI3K/AKT inhibitor LY294002, PPARγ inhibitor GW9662 and NF-κB activator LPS both reversed the effects of TEC on OGD/R-induced HT-22 cell biology. Taken together, this research confirmed that TEC benefit to HT-22 cell survival and against OGD/R damage through the PI3K/AKT and PPARγ/NF-κB pathways. These results indicated that TEC might be an effective compound in the treatment for ischemic brain injury.

1% Isoflurane and 1.2 μg/ml of Propofol: A Combination of Anesthetics That Causes the Least Damage to Hypoxic Neurons

Backgrounds: Aging-related impairment of cerebral blood flow regulation leads to the disruption of neuronal micro-environmental homeostasis. Anesthetics should be carefully selected for aging patients since they have less cognition capacity. Effects and mechanisms of propofol or isoflurane have been widely investigated. However, how different combinations of propofol and isoflurane affect neurons and the mechanism still needs to be demonstrated.

Methods: We cultured rat hippocampal neurons and established a hypoxic injury model to imitate the micro-environment of aging brains. Three different combinations of propofol and isoflurane were applied to find out an optimum group via Cell Counting Kit-8 (CCK8) assay, lactic acid dehydrogenase (LDH) assay, real-time qPCR, and immunofluorescence of key proteins. Then BiP was silenced by small interfering RNA (siRNA) to explore the mechanism of how isoflurane and propofol affect neurons. Endoplasmic reticulum (ER) stress was measured by Western blot and immunofluorescence. To detect GABA_AR α1 subunit proteostasis and its function, real-time qPCR, immunoprecipitation, and Western blot were carried out.

Results: Hypoxic neurons showed no different changes on cell viability, LDH leakage, and ER stress after treatment with 1% isoflurane and 1.2 μg/ml of propofol. Hypoxic neurons showed a sharp increase of LDH leakage and ER stress and a decrease of cell viability after treatment with 1.4% isoflurane and 0.6 μg/ml of propofol or 0.5% isoflurane and 1.8 μg/ml of propofol. After knockdown of BiP, the application of 1% isoflurane and 1.2 μg/ml of propofol led to the decrease of GABA_AR α1 subunit protein content and viability of cell, as well as aggravation of ER stress.

Conclusion: A combination of 1% isoflurane and 1.2 μg/ml of propofol causes the least damage than do other dosages of both two drugs, and endogenous BiP plays an important role in this process.

Attenuation of chronic arsenic neurotoxicity via melatonin in male offspring of maternal rats exposed to arsenic during conception: Involvement of oxidative DNA damage and inflammatory signaling cascades

Prenatal exposure to arsenic is demonstrated to elevate the risk of brain damage and neurological disorders in the fetus, mainly due to its ability for crossing through the placental barriers. Increase in oxidative stress, inflammation, and DNA damage is main mechanisms of arsenic-induced neurotoxicity. Therefore, this study aimed to evaluate the neuroprotective effects of melatonin, as a potent anti-oxidant and anti-inflammatory agent against arsenic toxicity in the brains of male offspring rats. Pregnant mother rats were randomly assigned into four groups including group I, as control, group II received 10 mg/kg melatonin, group III received arsenic at 50 mg/kg, and group IV received melatonin and arsenic. After a two-month period, oxidative stress, DNA damage, inflammation and apoptosis were assessed in the male offspring rats. Exposure to arsenic significantly increased the pro-inflammatory and oxidative factors resulting in DNA damage and apoptosis in the brain tissues of offspring rats in comparison to controls (p < 0.05). Exogenous administration of melatonin showed a significant increase in the tissue levels of acetylcholine esterase, decrease in the lactate dehydrogenase and myeloperoxidase, when compared to arsenic group (p < 0.05). Melatonin also overcame the arsenic-induced oxidative stress and suppressed inflammation, DNA damage and apoptosis. Our results suggested that melatonin may be a promising neuro-protective agent and momentous therapy for the treatment of arsenic-toxicity in clinical conditions.

Propofol exerts neuroprotective functions by down-regulating microRNA-19a in glutamic acid-induced PC12 cells

BACKGROUND

Propofol, a kind of intravenous sedative drug, is certified that exerts anti-inflammation and antitumor functions. However, the influence of propofol in cerebral injury and the corresponding mechanism remains unexplained, that our article focuses on.

METHODS

PC12 cells were treated with propofol and exposed in glutamic acid (Glu) solutions. Cell viability, apoptotic potential, apoptosis-related and autophagy-linked proteins were tested via CCK-8, flow cytometry, and western blot assays. Reverse transcription-quantitative real-time PCR was utilized to test miR-19a expression in Glu-stimulated cells. Next, miR-19a mimic transfection was used to assess the effects of miR-19a on cell apoptosis and autophagy in Glu or propofol treated cells. Finally, western blot was performed to test AMPK and mTOR pathways.

RESULTS

Glu exposure promoted cell apoptosis and autophagy of PC12 cells, while propofol attenuated cell apoptosis and autophagy triggered by Glu. Additionally, propofol decreased the miR-19a expression in Glu-stimulated PC12 cells. Meanwhile, over-expression of miR-19a reversed the effects of propofol on Glu-induced cell apoptosis and autophagy. Moreover, propofol potentiated AMPK and mTOR pathways in Glu-stimulated PC12 cells via impeding miR-19a expression.

CONCLUSIONS

These finding revealed that propofol relieved Glu-triggered apoptosis and autophagy of PC12, and activated AMPK and mTOR pathways by suppressing miR-19a expression.

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.

Propofol alleviates ventilator-induced lung injury through regulating the Nrf2/NLRP3 signaling pathway

Ventilator-induced lung injury (VILI) causes problems during acute lung injury treatment, and propofol is a well-known drug to prevent VILI. Herein, we discussed how propofol protects against VILI-induced inflammation with the interaction of nuclear factor E2-related factor 2 (Nrf2)/NOD-like receptor protein 3 (NLRP3). We established VILI mouse models for collecting lung tissues, and these mice were later treated with propofol and Nrf2/NLRP3 activator or inhibitor to observe their effects on VILI with inflammatory factors, 8-hydroxy-2 deoxyguanosine, malondialchehyche level, mitochondrial reactive oxygen species production rate, lung wet/dry weight ratio, lung permeability index measured. Propofol treatment improved VILI, alleviated pulmonary inflammation induced by mechanical ventilation. Propofol up-regulated Nrf2 and down-regulated NLRP3 in VILI model. Activating Nrf2 or inhibiting NLRP3 downregulated pro-inflammatory factors in lung tissues in VILI mice. Above all, we can conclude that propofol exerts it protective function against VILI and the subsequent inflammatory responses through activating Nrf2 and inhibiting NLRP3 expression. Therefore, Nrf2 activator and NLRP3 inhibitor might be latent targets in the VILI prevention.

Piperine as a neuroprotective functional component in rats with cerebral ischemic injury

Long pepper (Piper longum L.) and black pepper (Piper nigrum L.) plants are commonly used as spices around the world and have also been postulated to have medicinal effects. Piperine, as the major alkaloid of P. nigrum and P. longum, has gained wide attention of the medical community and culinary enthusiasts. This study seeks to determine the effects of piperine on neuronal apoptosis in peri-infarcted cerebral cortices of rats with permanent middle cerebral artery occlusion (pMCAO) injury. Evaluation of the different behavioral components was conducted after pMCAO. 2, 3, 5-Triphenyltetrazolium chloride (TTC) was used to evaluate the area of cortical ischemia. Gross histopathological changes, as well as microscopic neuronal changes, were observed in brain tissue samples. The protein expression of Caspase-3, Caspase-9, Bax, Bcl-2, and Cytochrome C (Cyt-c) was analyzed using western blotting. The findings reveal that rats that received piperine treatment show markedly decreased neurological deficit, less ischemia-induced cellular damage, as well as smaller areas of cerebral infarction, with less severe macro and microcellular cerebral structural changes. Western blotting analysis reveals that piperine administration inhibits Bax, while enhancing Bcl-2 expression. The protein expression of Caspase-3, Caspase-9, and Cyt-c was also found to be significantly inhibited. We conclude that piperine may provide several beneficial neuroprotective effects that warrant further investigation.

Propofol Reduces Inflammatory Brain Injury after Subarachnoid Hemorrhage: Involvement of PI3K/Akt Pathway

BACKGROUND

Our previous study showed that propofol, one of the widely used anesthetic agents, can attenuate subarachnoid hemorrhage (SAH)-induced early brain injury (EBI) via inhibiting inflammatory and oxidative reaction. However, it is perplexing whether propofol attenuates inflammatory and oxidative reaction through modulating PI3K/Akt pathway. The present study investigated whether PI3K/Akt pathway is involved in propofol's anti-inflammation, antioxidation, and neuroprotection against SAH-induced EBI.

MATERIALS AND METHODS

Adult Sprague-Dawley rats underwent SAH and received treatment with propofol or vehicle after 2 and 12 hours of SAH. LY294002 was injected intracerebroventricularly to selectively inhibit PI3K/Akt signaling. Mortality, SAH grading, neurological scores, brain water content, evans blue extravasation, myeloperoxidase, malondialdehyde, superoxide dismutase, and glutathione peroxidase were measured 24 hours after SAH. Immunoreactivity of p-Akt, t-Akt, nuclear factor- kappa B (NF-κB) p65, nuclear factor erythroid-related factor 2 (Nrf2), NAD(P)H:quinone oxidoreductase (NQO1), and cyclooxygenase-2 (COX-2) in rat brain was determined by western blot. Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in rat brain were examined by ELISA.

RESULTS

Propofol significantly reduces neurological dysfunction, BBB permeability, brain edema, inflammation, and oxidative stress, all of which were reversed by LY294002. Propofol significantly upregulates the immunoreactivity of p-Akt, Nrf2, and NQO1, all of which were abolished by LY294002. Propofol significantly downregulates the overexpression of NF-κB p65, COX-2, TNF-α, and IL-1β, all of which were inhibited by LY294002.

CONCLUSION

These results suggest that propofol attenuates SAH-induced EBI by inhibiting inflammatory reaction and oxidative stress, which might be associated with the activation of PI3K/Akt signaling pathway.

N-Palmitoylethanolamide-Oxazoline Protects against Middle Cerebral Artery Occlusion Injury in Diabetic Rats by Regulating the SIRT1 Pathway

Diabetes causes various macrovascular and microvascular alterations, often culminating in major clinical complications (first of all, stroke) that lack an effective therapeutic intervention. N-palmitoylethanolamide-oxazoline (PEA-OXA) possesses anti-inflammatory and potent neuroprotective effects. Although recent studies have explained the neuroprotective properties of PEA-OXA, nothing is known about its effects in treating cerebral ischemia. Methods: Focal cerebral ischemia was induced by transient middle cerebral artery occlusion (MCAo) in the right hemisphere. Middle cerebral artery (MCA) occlusion was provided by introducing a 4–0 nylon monofilament (Ethilon; Johnson & Johnson, Somerville, NJ, USA) precoated with silicone via the external carotid artery into the internal carotid artery to occlude the MCA. Results: A neurological severity score and infarct volumes were carried out to assess the neuroprotective effects of PEA-OXA. Moreover, we observed PEA-OXA-mediated improvements in tissue histology shown by a reduction in lesion size and an improvement in apoptosis level (assessed by caspases, Bax, and Bcl-2 modulation and a TUNEL assay), which further supported the efficacy of PEA-OXA therapy. We also found that PEA-OXA treatment was able to reduce mast cell degranulation and reduce the MCAo-induced expression of NF-κB pathways, cytokines, and neurotrophic factors. Conclusions: based on these findings, we propose that PEA-OXA could be useful in decreasing the risk of impairment or improving function in ischemia/reperfusion brain injury-related disorders.

ERK activation by zeranol has neuroprotective effect in cerebral ischemia reperfusion

AIMS

Incidence of stroke increases in postmenopausal women with dangerous consequences. In this study we used zeranol to protect ovariectomized (OVX) rats against cerebral I/R damage and our target is to identify the mechanism of its protection, in addition to investigating whether this mechanism inhibits inflammation (by preventing glial cell activation) and apoptosis.

MAIN METHODS

First 18 ovariectomized rats were allocated into 3 groups: I/R group, zeranol+ I/R group and U0126, MEK1/2 inhibitor + zeranol+ I/R group. After 24 h reperfusion, protein expression of total extracellular signal-regulated protein kinase (t-ERK1/2), phosphorylated extracellular signal-regulated protein kinase (p-ERK1/2), Bcl-2, and Bax were quantified. Second 36 female rats were allocated into 3 groups: sham group, I/R group (after ovariectomy by 7 weeks, rats exposed to cerebral I/R) and zeranol group (after ovariectomy by 2 weeks, rats received zeranol for 5 weeks). After 24 h of reperfusion, the following parameters were measured; total nitrate/nitrite, interleukin-10, myeloperoxidase, caspase-3, and finally immunohistochemistry analysis of glial fibrillary acidic protein, cyclooxygenase-2 in cortex and hippocampus (CA1) regions were performed.

KEY FINDINGS

U-0126 administration reversed the neuroprotective effect induced by zeranol through decreasing ratio of p-ERK1/2:ERK1/2 and Bcl-2/Bax in brain tissue. Activation of ERK signaling pathway by zeranol caused reduction in brain apoptosis and inflammation.

SIGNIFICANCE

Zeranol showed protective effect in OVX rats that were exposed to cerebral I/R by activation of ERK signaling pathway which was blocked by U0126. This protective effect in turns led to decrease inflammation and apoptosis.

The role of PI3K/Akt signal pathway in the protective effects of propofol on intestinal and lung injury induced by intestinal ischemia/reperfusion1

Purpose

To investigate the role of PI3k/Akt signal pathway in the protective effects of propofol on intestinal and lung injury induced by intestinal ischemia/reperfusion(I/R).

Methods

Male Sprague-Dawley rats were subjected to 45 min of ischemia by occluding the superior mesenteric artery and to 2h of reperfusion to establish the model of I/R. Twenty four rats were randomly divided into four groups: Sham, intestinal I/R (II/R), propofol (P), wortmannin (W). In groups P, W, propofol was injected intravenously and continuously at the onset of reperfusion via infusion pump. PI3K inhibitor (wortmannin) was administered intravenously in group W 25 min before ischemia. Intestinal tissues and lung tissues were obtained for determination of histologic injury, wet/dry weight ratio, malondialdehyde (MDA) levels, superoxide dismutase (SOD) and myeloperoxidase (MPO) activities. Meanwhile, the expressions of caspase-3 and phosphorylated Akt (p-Akt) in intestines and lungs were detected by western blot.

Results

Propofol treatment alleviated intestinal and lung morphological changes which were observed in II/R group , Moreover, wet/dry weight ratio, the MDA level, MPO activity and expression of caspase-3 were significantly decreased whereas the SOD activity and p-Akt expression were significantly increased. Notably, the protections were significantly reversed by pretreatment of wortmannin.

Conclusion:

PI3K/Akt pathway activation play a critical role in the protective effects of propofol on intestinal and lung injury induced by ischemia/reperfusion.

Naomaitai Ameliorated Brain Damage in Rats with Vascular Dementia by PI3K/PDK1/AKT Signaling Pathway

Background/Aims

Naomaitai can improve blood perfusion and ameliorate the damage in the paraventricular white matter. This study was focused on observing the neuroprotective effect of Naomaitai on the vascular dementia of rat and exploring the action mechanism of PI3K/PDK1/AKT signaling pathway.

Methods

A vascular dementia model of rats was established by permanent, bilateral common carotid artery occlusion. Rats' behavior was tested by Neurological deficit score and the Morris water maze. The pathology and apoptosis were detected through HE staining and TUNEL assay. Myelin sheath loss and nerve fiber damage were detected by LFB staining. Inflammatory factors, oxidative stress, and brain damage markers were detected through ELISA. The expression of apoptosis-related proteins and PI3K/PDK1/AKT signaling pathway related proteins were measured by western blot. The expressions of PI3K, PDK1, AKT, and MBP in paraventricular white matter cells were detected by immunofluorescence.

Results

Naomaitai treatment decreased neurological function score in rats with vascular dementia, ameliorated paraventricular white matter damage caused by long-term hypoxia, and hypoperfusion reduced the brain injury markers S-100β and NSE contents, suppressed inflammatory reaction and oxidative stress, reduced IL-1β, IL-6, TNF-α, and MDA contents, and remarkably increased IL-10 and SOD contents. TUNEL and western blot assay showed that Naomaitai treatment decreased neuronal cell apoptosis, increased Bcl-2 expression, and reduced caspase-3 and Bax expression. Furthermore, we found Naomaitai inhibited PI3K and PDK1 expression and activated phosphorylated AKT protein in rats with vascular dementia. However, the protective effect of Naomatai in rats with vascular dementia was inhibited, and expression of PI3K signaling pathway-related proteins was blocked after administration of PI3K inhibitor.

Conclusion

Naomaitai can ameliorate brain damage in rats with vascular dementia, inhibit neuronal apoptosis, and have anti-inflammatory and antioxidative stress effects, which may be regulated by the PI3K/PDK1/AKT signaling pathway.

Luteoloside attenuates neuroinflammation in focal cerebral ischemia in rats via regulation of the PPARγ/Nrf2/NF-κB signaling pathway

Luteoloside, a flavonoid compound, has been reported to have anti-inflammatory, anti-oxidative, antibacterial, antiviral, anticancer, and cardioprotective effects, among others, but its neuroprotective effects have rarely been studied. The purpose of this study was to investigate the protective effect of luteoloside on cerebral ischemia and explore its potential mechanism. Middle cerebral artery occlusion (MCAO) was performed to investigate the effects of luteoloside on cerebral ischemia-reperfusion (I/R). Male Sprague-Dawley rats were randomly divided into six groups: sham, MCAO, luteoloside (20 mg/kg, 40 mg/kg, 80 mg/kg) and nimodipine (4 mg/kg). The results showed that luteoloside alleviated neurologic deficits and cerebral edema as well as improved cerebral infarction and histopathological changes in MCAO rats. Luteoloside significantly inhibited I/R-induced neuroinflammation, as demonstrated by reduced levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the brain tissues of MCAO rats. Furthermore, our results demonstrated that luteoloside significantly suppressed the activation of nuclear factor-kappa B (NF-κB) signaling, upregulated the protein expression of peroxisome proliferator activated receptor gamma (PPARγ) and increased NF-E2-related factor (Nrf2) nuclear accumulation in MCAO rats. Collectively, our findings suggested that luteoloside played a crucial neuroprotective role by inhibiting NF-κB signaling in focal cerebral ischemia in rats. Furthermore, PPARγ and Nrf2 were also important for the anti-inflammatory effect of luteoloside. In addition, our data suggested that luteoloside might be an effective treatment for cerebral ischemia and other neurological disorders.

Propofol inhibits parthanatos via ROS-ER-calcium-mitochondria signal pathway in vivo and vitro

Parthanatos is a new form of programmed cell death. It has been recognized to be critical in cerebral ischemia–reperfusion injury, and reactive oxygen species (ROS) can induce parthanatos. Recent studies found that propofol, a widely used intravenous anesthetic agent, has an inhibitory effect on ROS and has neuroprotective in many neurological diseases. However, the functional roles and mechanisms of propofol in parthanatos remain unclear. Here, we discovered that the ROS–ER–calcium–mitochondria signal pathway mediated parthanatos and the significance of propofol in parthanatos. Next, we found that ROS overproduction would cause endoplasmic reticulum (ER) calcium release, leading to mitochondria depolarization with the loss of mitochondrial membrane potential. Mitochondria depolarization caused mitochondria to release more ROS, which, in turn, contributed to parthanatos. Also, we found that propofol inhibited parthanatos through impeding ROS overproduction, calcium release from ER, and mitochondrial depolarization in parthanatos. Importantly, our results indicated that propofol protected cerebral ischemia–reperfusion via parthanatos suppression, amelioration of mitochondria, and ER swelling. Our findings provide new insights into the mechanisms of how ER and mitochondria contribute to parthanatos. Furthermore, our studies elucidated that propofol has a vital role in parthanatos prevention in vivo and in vitro, and propofol can be a promising therapeutic approach for nerve injury patients.

Validation and bioinformatic analysis of propofol-induced differentially expressed microRNAs in primary cultured neural stem cells

Propofol, a widely used intravenous anesthetic, was previously considered as a neuroprotective agent. Recently, however, accumulating evidence suggests that it may cause neurotoxicity, especially in the development of neural stem cells (NSCs). The potential mechanisms contributing to propofol-induced neurotoxicity during neurogenesis, such as those involving microRNAs (miRNAs), are still unknown. In this study, a total of 27 differentially expressed miRNAs were identified in our initial screen and 6 miRNAs were validated by qRT-PCR. Three miRNAs were up-regulated (miR-377-5p, miR-194-3p and miR-143-5p), and three were down-regulated (miR-3583-3p, miR-466b-5p and miR-410-5p). Following gene ontology and KEGG pathway enrichment analysis, Gabbr1, Canca1b and Gabbr2, which are enriched in the GABAergic synapse pathway, were selected as genes potentially playing a role in propofol-induced neurotoxicity. Gabbr1 and Cacna1b, which are targeted by miRNAs that are up-regulated following propofol exposure, showed decreased expression at the mRNA and protein levels. Gabbr2, targeted by miRNAs that were down-regulated following treatment with propofol, was up-regulated at both the levels of mRNA and protein expression. The two clusters of miRNAs that show differential expression following propofol exposure may act in a synergistic manner to regulate several genes simultaneously during the development of NSCs. Our results may contribute to clarify the molecular mechanism and provide potential therapeutic targets for propofol induced neurotoxicity.

Liraglutide Activates the Nrf2/HO-1 Antioxidant Pathway and Protects Brain Nerve Cells against Cerebral Ischemia in Diabetic Rats

This study aimed to determine the effect of liraglutide pretreatment and to elucidate the mechanism of nuclear factor erythroid 2-related factor (Nrf2)/heme oxygenase-1 (HO-1) signaling after focal cerebral ischemia injury in diabetic rats model. Adult male Sprague-Dawley rats were randomly divided into the sham-operated (S) group, diabetes mellitus ischemia (DM + MCAO) group, liraglutide pretreatment normal blood glucose ischemia (NDM+MCAO+L) group, and liraglutide pretreatment diabetes ischemia (DM + MCAO + L) group. At 48 h after middle cerebral artery occlusion (MCAO), neurological deficits and infarct volume of brain were measured. Oxidative stress brain tissue was determined by superoxide dismutase (SOD) and myeloperoxidase (MPO) activities. The expression levels of Nrf2 and HO-1 of brain tissue were analyzed by western blotting. In the DM + MCAO + L group, neurological deficits scores and cerebral infarct volume seemed to decrease at 48 h after MCAO cerebral ischemia compared with those in DM + MCAO group (P < 0.05). In addition, the expression of Nrf2 and HO-1 increased in 48 h at liraglutide pretreatment groups after MCAO cerebral ischemia if compared with those in the DM + MCAO group (P < 0.05). Furthermore, the DM + MCAO + L group has no significant difference compared with the NDM + MCAO + L group (P > 0.05). To sum up, alleviating effects of liraglutide on diabetes complicated with cerebral ischemia injury rats would be related to Nrf2/HO-1 signaling pathway.

Propofol, but not ketamine or midazolam, exerts neuroprotection after ischaemic injury by inhibition of Toll-like receptor 4 and nuclear factor kappa-light-chain-enhancer of activated B-cell signalling: A combined in vitro and animal study

BACKGROUND

Propofol, midazolam and ketamine are widely used in today's anaesthesia practice. Both neuroprotective and neurotoxic effects have been attributed to all three agents.

OBJECTIVE

To establish whether propofol, midazolam and ketamine in the same neuronal injury model exert neuroprotective effects on injured neurones in vitro and in vivo by modulation of the Toll-like receptor 4-nuclear factor kappa-light-chain-enhancer of activated B cells (TLR-4-NF-κB) pathway.

DESIGN AND SETTING

Cell-based laboratory (n = 6 repetitions per experiment) and animal (n = 6 per group) studies using a neuronal cell line (SH-SY5Y cells) and adult Sprague-Dawley rats.

INTERVENTIONS

Cells were exposed to oxygen-glucose deprivation before or after treatment using escalating, clinically relevant doses of propofol, midazolam and ketamine. In animals, retinal ischaemia (60 min) was induced followed by reperfusion and randomised treatment with saline or propofol.

MAIN OUTCOME MEASURES

Neuronal cell death was determined using flow-cytometry (mitochondrial membrane potential) and lactate dehydrogenase (LDH) release. Nuclear factor NF-κB and hypoxia-inducible factor 1 α-activity were analysed by DNA-binding ELISA, expression of NF-κB-dependent genes and TLR-4 by luciferase-assay and flow-cytometry, respectively. In animals, retinal ganglion cell density, caspase-3 activation and gene expression (TLR-4, NF-κB) were used to determine in vivo effects of propofol. Results were compared using ANOVA (Analysis of Variance) and t test. A P value less than 0.05 was considered statistically significant.

RESULTS

Post-treatment with clinically relevant concentrations of propofol (1 to 10 μg ml) preserved the mitochondrial membrane potential in oxygen-glucose deprivation-injured cells by 54% and reduced LDH release by 21%. Propofol diminished TLR-4 surface expression and preserved the DNA-binding activity of the protective hypoxia-inducible factor 1 α transcription factor. DNA-binding and transcriptional NF-κB-activity were inhibited by propofol. Neuronal protection and inhibition of TLR-4-NF-κB signalling were not consistently seen with midazolam or ketamine. In vivo, propofol treatment preserved rat retinal ganglion cell densities (cells mm, saline 1504 ± 251 vs propofol 2088 ± 144, P = 0.0001), which was accompanied by reduced neuronal caspase-3, TLR-4 and NF-κB expression.

CONCLUSION

Propofol, but neither midazolam nor ketamine, provides neuroprotection to injured neuronal cells via inhibition of TLR-4-NF-κB-dependent signalling.

Changes in transcranial electrical motor-evoked potentials during the early and reversible stage of permanent spinal cord ischemia predict spinal cord injury in a rabbit animal model

The present study examined changes in the transcranial electrical motor-evoked potentials (TceMEP) waveform to predict neurological deficits and histopathological changes during the early and reversible stage of different levels of permanent spinal cord ischemic injury in a rabbit animal model. A total of 24 New Zealand rabbits were randomly divided into four groups of 6 rabbits each. Group 1 underwent a ligation of the lumbar artery at three levels (L1-L3), group 2 underwent a ligation of the lumbar artery at four levels (L1-L4) and group 3 underwent a ligation of the lumbar artery at five levels (L1-L5). The sham group contained 6 rabbits and did not receive ligation. TceMEP was recorded within 5 min of ligation and, 2 days later, motor function was assessed and the spinal cords were removed for histological examination. Following spinal cord injury, the relationship between variations in the TceMEP waveform and motor function and pathological damage was analyzed. It was observed that the amplitude of TceMEP began to decrease within 1 min of lumbar artery ligation and that the amplitude stabilized within 5 min. These amplitude changes that occurred within 5 min of different levels of permanent spinal cord ischemic injury were positively related to changes in motor function following recovery from anesthesia and 2 days after ligation. The Pearson correlation coefficient was 0.980 and 0.923 for these two time points, respectively (P<0.001). In addition, the amplitude changes were positively related to pathological damage, with a Pearson correlation coefficient of 0.945 (P<0.001). The results of the present study suggested that amplitude changes in TceMEP are particularly sensitive to ischemia. Ischemia may be detected within 1 min and the amplitude changes begin to stabilize within 5 min following ligation of the lumbar artery. The use of intraoperative monitoring of TceMEP allows for the detection of spinal cord ischemic injury with no time delay, which may allow for protective measures to be taken to prevent the occurrence of irreversible spinal cord injury.

Impact of propofol on renal ischemia/reperfusion endoplasmic reticulum stress

Purpose:

To investigate the protective mechanisms of propofol (Pro) on renal ischemia/reperfusion (I/R) injury by studying its impact on renal I/R endoplasmic reticulum stress.

Methods:

Eighteen male Sprague-Dawley rats (SD rats) were randomly divided into three groups: the I/R group, the Pro pretreatment group, and the control group, and corresponding treatments were performed. The levels of serum creatinine (Cr) and blood urea nitrogen (BUN) of each group were detected. The expression levels of CCAAT-enhancer-binding protein (C/EBP) homology protein (CHOP) and caspase-12 protein within renal tissue samples were detected by western blot.

Results:

The periodic acid-Schiff (PAS) staining was performed to observe the morphological changes within the renal tissues, and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay was performed to detect the presence of renal apoptosis. The Pro pretreatment significantly reduced the serum Cr and BUN levels, as well as the expressions levels of CHOP and caspase-12 protein inside the kidney of I/R rats, improving renal pathological injury and reducing the I/R-induced renal apoptosis.

Conclusion:

Propofol could downregulate the expression of stress-apoptotic proteins CHOP and caspase-12 in the endoplasmic reticulum, thus reducing renal I/R injury.

Propofol administration improves neurological function associated with inhibition of pro-inflammatory cytokines in adult rats after traumatic brain injury

BACKGROUND

Neurological deficits following traumatic brain injury (TBI) result in dramatic impacts on the survivors, but the effect of propofol and associated mechanism are waiting to be determined.

METHODS

Adult male Sprague-Dawley rats were randomly assigned into Sham, TBI, TBI+Intralipid and TBI+Propofol group. Modified Feeney method was adopted to generate TBI model from free hammer fall injury, and animals in TBI+Propofol group were immediately treated with propofol administration for 2hours after TBI, rats after TBI without propofol treatment was used as injury control, intralipid as vehicle in propofol was injected in TBI+intralipid group. Then, neurological severity scores (NSS) were evaluated at 1, 3, 7 and 14days. Moreover, the expressions of IL-1β, IL-6 and TNF-α mRNA and protein were examined using quantitative real time-polymerase chain reaction and Western blot, immunohistochemical staining was used to localize cytokines.

RESULTS

The NSS increased greatly in the rats induced by TBI, while propofol could effectively decreased NSS, confirming the neuroprotective effect of propofol. Moreover, the mRNA expressions of IL-1β, IL-6 and TNF-α, at 1, 3, 7days after operation (dpo), were significantly augmented in the injured cortex, compared with sham one. But there was no difference between TBI and TBI+Intralipid group, but markedly decreased after propofol treatment. Additionally, the protein level of IL-1β, IL-6 and TNF-α in four groups determined by Western blot and immunohistochemistry showed the similar change with mRNA expression.

CONCLUSION

Propofol treatment could elicit a robust neuroprotective response, resulting in significant neurological function improvement for TBI rats, which was independent with intralipid. The underlying molecular mechanism may be partially associated with an inhibition of pro-inflammatory cytokines.

Propofol Enhances Hemoglobin-Induced Cytotoxicity in Neurons

BACKGROUND

It has been increasingly suggested that propofol protects against hypoxic-/ischemic-induced neuronal injury. As evidenced by hemorrhage-induced stroke, hemorrhage into the brain may also cause brain damage. Whether propofol protects against hemorrhage-induced brain damage remains unknown. Therefore, in this study, we investigated the effects of propofol on hemoglobin-induced cytotoxicity in cultured mouse cortical neurons.

METHODS

Neurons were prepared from the cortex of embryonic 15-day-old mice. Hemoglobin was used to induce cytotoxicity in the neurons. The neurons were then treated with propofol for 4 hours. Cytotoxicity was determined by lactate dehydrogenase release assay. Caspase-3 activation was examined by Western blot analysis. Finally, the free radical scavenger U83836E was used to examine the potential involvement of oxidative stress in propofol's effects on hemoglobin-induced cytotoxicity.

RESULTS

We found that treatment with hemoglobin induced cytotoxicity in the neurons. Propofol enhanced hemoglobin-induced cytotoxicity. Specifically, there was a significant difference in the amount of lactate dehydrogenase release between hemoglobin plus saline (19.84% ± 5.38%) and hemoglobin plus propofol (35.79% ± 4.41%) in mouse cortical neurons (P = 0.00058, Wilcoxon Mann-Whitney U test, n = 8 in the control group or the treatment group). U83836E did not attenuate the enhancing effects of propofol on hemoglobin-induced cytotoxicity in the neurons, and propofol did not significantly affect caspase-3 activation induced by hemoglobin. These data suggested that caspase-3 activation and oxidative stress might not be the underlying mechanisms by which propofol enhanced hemoglobin-induced cytotoxicity. Moreover, these data suggested that the neuroprotective effects of propofol would be dependent on the condition of the brain injury, which will need to be confirmed in future studies.

CONCLUSIONS

These results from our current proof-of-concept study should promote more research in vitro and in vivo to develop better anesthesia care for patients with hemorrhagic stroke.

Neuroinflammatory response to experimental stroke is inhibited by eriodictyol

BACKGROUND

Cerebral ischemia is a common disease and one of the most common causes of death and disability worldwide. The lack of glucose and oxygen in neuronal tissue leads to a series of inflammatory events, culminating in neuronal death. Eriodictyol is a flavonoid isolated from the Chinese herb Dracocephalum rupestre that has been proven to have anti-inflammatory properties.

HYPOTHESIS/PURPOSE

Thus, the present study was designed to explore whether eriodictyol has neuroprotective effects against the neuronal damage, motor and memory deficits induced by permanent middle cerebral artery occlusion (pMCAO) in mice.

STUDY DESIGN

Animals were orally treated with eriodictyol (1, 2 and 4mg/kg) or vehicle (saline) 30min before pMCAO, 2h after, and then once daily for the following five days.

METHODS

The parameters studied were neuronal viability, brain infarcted area; sensorimotor deficits; exploratory activity; working and aversive memory; myeloperoxidase (MPO) activity; TNFα, iNOS and GFAP immunoreactivity.

RESULTS

The treatment with eriodictyol prevented neuronal death, reduced infarct area and improved neurological and memory deficits induced by brain ischemia. The increase of MPO activity and TNF-α, iNOS and GFAP expression were also reduced by eriodictyol treatment.

CONCLUSION

These findings demonstrate that eriodictyol exhibit promising neuroprotection effects against the permanent focal ischemia cerebral injury in the mice experimental model and the underlying mechanisms might be mediated through inhibition of neuroinflammation.

Propofol Attenuates Early Brain Injury After Subarachnoid Hemorrhage in Rats

Our previous studies demonstrated that propofol protects rat brain against focal cerebral ischemia. However, whether propofol attenuates early brain injury after subarachnoid hemorrhage in rats remains unknown until now. The present study was performed to evaluate the effect of propofol on early brain injury after subarachnoid hemorrhage in rats and further explore the potential mechanisms. Sprague-Dawley rats underwent subarachnoid hemorrhage (SAH) by endovascular perforation then received treatment with propofol (10 or 50 mg/kg) or vehicle after 2 and 12 h of SAH. SAH grading, neurological scores, brain water content, Evans blue extravasation, the myeloperoxidase activity, and malondialdehyde (MDA) content were measured 24 h after SAH. Expression of nuclear factor erythroid-related factor 2 (Nrf2), nuclear factor-kappa B (NF-κB) p65, and aquaporin 4 (AQP4) expression in rat brain were detected by Western blot. Expression of cyclooxygenase-2 (COX-2) and matrix metalloproteinase-9 (MMP-9) were determined by reverse transcription-polymerase chain reaction (RT-PCR). Expressions of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were assessed by ELISA. Neurological scores, brain water content, Evans blue extravasation, the myeloperoxidase activity, and MDA content were significantly reduced by propofol. Furthermore, expression of Nrf2 in rat brain was upregulated by propofol, and expression of NF-κB p65, AQP4, COX-2, MMP-9, TNF-α, and IL-1β in rat brain were attenuated by propofol. Our results demonstrated that propofol improves neurological scores, reduces brain edema, blood-brain barrier (BBB) permeability, inflammatory reaction, and lipid peroxidation in rats of SAH. Propofol exerts neuroprotection against SAH-induced early brain injury, which might be associated with the inhibition of inflammation and lipid peroxidation.

Anesthetic Propofol Attenuates Apoptosis, Aβ Accumulation, and Inflammation Induced by Sevoflurane Through NF-κB Pathway in Human Neuroglioma Cells

Anesthetics have been reported to promote Alzheimer's disease neuropathogenesis by inducing amyloid beta (Aβ) protein accumulation and apoptosis. The aim of this study was to evaluate the effect of propofol on the apoptosis, Aβ accumulation, and inflammation induced by sevoflurane in human neuroglioma cells. Human neuroglioma cells were treated with or without sevoflurane and then co-incubated with or without propofol. Cell apoptosis was evaluated by fluorescence-activated cell sorting analysis (FACS) using AV-PI kits, and data showed that apoptosis induced by sevoflurane was significantly attenuated by propofol treatment. In addition, with the reactive oxygen species (ROS) production measured by FACS after staining with dichloro-dihydrofluorescein diacetate, propofol could significantly reduce the production of ROS as well as the accumulation of Aβ induced by sevoflurane assessed by enzyme-linked immuno sorbent assay (ELISA) analysis. On the other hand, the same treatment decreased the inflammation factor production of interleukin-6. Moreover, the level of nuclear factor-kappa B (NF-κB) was tested by Western blot and immunofluorescence assay. We found that the activation of NF-κB pathway was suppressed by propofol. The results suggest that propofol can effectively attenuate the apoptosis, Aβ accumulation, and inflammation induced by sevoflurane in human neuroglioma cells through NF-κB signal pathway.

Propofol inhibits burn injury-induced hyperpermeability through an apoptotic signal pathway in microvascular endothelial cells

Recent studies have revealed that an intrinsic apoptotic signaling cascade is involved in vascular hyperpermeability and endothelial barrier dysfunction. Propofol (2,6-diisopropylphenol) has also been reported to inhibit apoptotic signaling by regulating mitochondrial permeability transition pore (mPTP) opening and caspase-3 activation. Here, we investigated whether propofol could alleviate burn serum-induced endothelial hyperpermeability through the inhibition of the intrinsic apoptotic signaling cascade. Rat lung microvascular endothelial cells (RLMVECs) were pretreated with propofol at various concentrations, followed by stimulation with burn serum, obtained from burn-injury rats. Monolayer permeability was determined by transendothelial electrical resistance. Mitochondrial release of cytochrome C was measured by ELISA. Bax and Bcl-2 expression and mitochondrial release of second mitochondrial-derived activator of caspases (smac) were detected by Western blotting. Caspase-3 activity was assessed by fluorometric assay; mitochondrial membrane potential (Δψm) was determined with JC-1 (a potential-sensitive fluorescent dye). Intracellular ATP content was assayed using a commercial kit, and reactive oxygen species (ROS) were measured by dichlorodihydrofluorescein diacetate (DCFH-DA). Burn serum significantly increased monolayer permeability (P<0.05), and this effect could be inhibited by propofol (P<0.05). Compared with a sham treatment group, intrinsic apoptotic signaling activation - indicated by Bax overexpression, Bcl-2 downregulation, Δψm reduction, decreased intracellular ATP level, increased cytosolic cytochrome C and smac, and caspase-3 activation - was observed in the vehicle group. Propofol not only attenuated these alterations (P<0.05 for all), but also significantly decreased burn-induced ROS production (P<0.05). Propofol attenuated burn-induced RLMVEC monolayer hyperpermeability by regulating the intrinsic apoptotic signaling pathway.

Mast cells and neuroinflammation

It has been determined that there is extensive communication between the immune system and the central nervous system (CNS). Proinflammatory cytokines play a key role in this communication. There is an emerging realization that glia and microglia, in particular, (which are the brain’s resident macrophages), are an important source of inflammatory mediators and may have fundamental roles in CNS disorders. Microglia respond also to proinflammatory signals released from other non-neuronal cells, principally those of immune origin, such as mast cells. Mast cells reside in the CNS and are capable of migrating across the blood-brain barrier (BBB) in situations where the barrier is compromised as a result of CNS pathology. Mast cells are both sensors and effectors in communication among nervous, vascular, and immune systems. In the brain, they reside on the brain side of the BBB, and interact with astrocytes, microglia, and blood vessels via their neuroactive stored and newly synthesized chemicals. They are first responders, acting as catalysts and recruiters to initiate, amplify, and prolong other immune and nervous responses upon activation. Mast cells both promote deleterious outcomes in brain function and contribute to normative behavioral functioning, particularly cognition and emotion. Mast cells may play a key role in treating systemic inflammation or blockade of signaling pathways from the periphery to the brain.

Montelukast, a cysteinyl leukotriene receptor-1 antagonist protects against hippocampal injury induced by transient global cerebral ischemia and reperfusion in rats

Cysteinyl leukotrienes (CysLTs) are potent pro-inflammatory and immune modulating lipid mediators involved in inflammatory diseases and were boosted in human brain after acute phase of cerebral ischemia. The antagonism of CysLTs receptors may offer protection against ischemic damage. Therefore it seemed interesting to study the possible neuroprotective effect of Montelukast, a CysLTR1 antagonist in global cerebral ischemia/reperfusion (IR) injury in rats. Global cerebral ischemia-reperfusion was induced by bilateral carotid artery occlusion for 15 min followed by 60 min reperfusion period. Animals were randomly allocated into three groups (n = 30 per group): Sham operated, I/R control and rats treated with montelukast (0.5 mg/kg, po) daily for 7 days then I/R was induced 1 h after the last dose of montelukast. After reperfusion rats were killed by decapitation, brains were removed and both hippocampi separated and the following biochemical parameters were estimated; lactate dehydrogenase activity, oxidative stress markers (lipid peroxides, nitric oxide and reduced glutathione), inflammatory markers (myeloperoxidase, tumor necrosis factor-alpha, nuclear factor kappa-B, interleukin-6 and interleukin-10), apoptotic biomarkers (caspase 3 and cytochrome C), neurotransmitters (glutamate, gamma aminobutyric acid), Cys-LTs contents and CysLT1 receptor expression; as well as total brain infarct size and histopathological examination of the hippocampus were assessed. Montelukast protected hippocampal tissue by reducing oxidative stress, inflammatory and apoptotic markers. Furthermore, it reduced glutamate and lactate dehydrogenase activity as well as infarct size elevated by I/R. These results were consistent with the histopathological findings. Montelukast showed a neuroprotective effects through antioxidant, anti-inflammatory and antiapoptotic mechanisms.