Sevoflurane-induced Neurotoxicity Research Articles

Overexpression of lncRNA Gm15621 alleviates apoptosis and inflammation response resulting from sevoflurane treatment through inhibiting miR-133a/Sox4.

Sevoflurane is the most widely used anesthetic administered by inhalation. Exposure to sevoflurane can elicit learning deficits and abnormal cognitive disorder. In this study, we investigated the function of long noncoding RNA (lncRNA) Gm15621. Primary hippocampal neuron cells were used to analyze the function of lncRNA Gm15621 in vitro. The tunel, inflammation markers, and cell survival rates were detected to evaluate the function of lncRNA Gm15621. Dual-luciferase reporter assay was used to identify the interaction between microRNA 133a and Gm15621. We found that lncRNA Gm15621 located in the cytoplasm. The expression of lncRNA Gm15621 was decreased with the development of sevoflurane exposure. Overexpression of lncRNA Gm15621 significantly reduced the apoptosis and cell survival rates. The inflammation response was also attenuated in lncRNA Gm15621 overexpressed group. The dual-luciferase assay revealed that miR-133a was the direct target of lncRNA Gm15621. In addition, we also found that Sox4 was a downstream target of miR-133a and lncRNA Gm15621 exerted its biological functions by regulating the expression of Sox4. In summary, our findings revealed that lncRNA Gm15621 ameliorated the sevoflurane-induced neurotoxicity and the important role of Gm15621/miR-133a/Sox4 axis in cognitive disorder.

LncRNA MALAT1 is involved in sevoflurane-induced neurotoxicity in developing rats.

The purpose of this study is to uncover the effects of long chain noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on sevoflurane-induced neurotoxicity in developing rats. Sevoflurane neurotoxicity model was established by sevoflurane treatment in 7-day-old Sprague-Dawley rats. The rats were treated with Sevo or MALAT1 small interfering RNA to detect the MALAT1 expression, pathological change, ultrastructure, neuronal apoptosis, expression of apoptosis-related proteins, expression of neurotrophic factors BDNF and NGF, spatial learning and memory function change, as well as neuron cell density of hippocampal tissues. MALAT1 was highly expressed in hippocampus tissues of rats. Downregulation of MALAT1 alleviated the pathological change, improved the ultrastructure, inhibited apoptosis of neuronal cells, declined caspase 3 and Bax while elevated Bcl-2, BDNF and NGF, improved capability of spatial learning and memory, and increased density of hippocampal neurons in hippocampal tissues of sevoflurane-induced rats. Suppression of MALAT1 can reduce the apoptosis of hippocampal neurons induced by sevoflurane anesthesia, improve the capability of spatial learning, and memory function and alleviate the loss of hippocampal nerve cells in developing rats. To a certain extent, it plays the role of protecting brain nerve cells.

Pre-administration of luteoline attenuates neonatal sevoflurane-induced neurotoxicity in mice

Sevoflurane is a widely used inhaled anesthetic, which triggers neuroapoptosis and oxidative damage in the developing central nervous system and cognitive dysfunction later in life. However, no effective therapeutic strategy for sevoflurane-induced deleterious effects is well developed. The purpose of the present study was to explore whether luteoline could attenuate neonatal sevoflurane exposure-triggered neurotoxicity. In this study, six-day-old C57BL/6 mice were pretreated with luteoline (30, 60 mg/kg) intraperitoneally for 30 min before exposed to 3% sevoflurane 6 h consecutively. We first examined the effects of luteoline on hippocampal neuron apoptosis, inflammation and oxidative stress 18 h post anesthesia. The spatial learning and memory performance was measured using Morris water maze test from postnatal day 31 to 38. The results showed that luteoline ameliorated neuronal apoptosis as evidenced by decrease of apoptotic cells, downregulation of the cleavage levels of caspase-3 and PRAP, and inactivation of caspase-3. Moreover, luteoline significantly decreased protein expressions of inflammatory cytokines (IL-1β, IL-18 and TNF-α), inhibited NF-кB/NLRP3 pathway (NF-кB, NLRP3, ASC and caspase-1) and suppressed NF-кB activity. Our analyses indicated that luteoline had a significant effect on decreasing the contents of ROS and MDA, elevating the activity of SOD, and ultimately improving spatial learning and memory deficits of mice. In summary, our findings confirm that the attenuation of luteoline on sevoflurane-induced spatial learning and memory impairment later is associated with inhibition of hippocampal neuron apoptosis, inflammation and oxidative stress early. Luteoline might be a potential therapeutic for sevoflurane anesthesia-induced neurobehavioral dysfunction.

Euxanthone Ameliorates Sevoflurane-Induced Neurotoxicity in Neonatal Mice.

Sevoflurane is a widely used anesthetic. A series of recent studies have shown that exposure to sevoflurane at an early stage is a risk factor for the development of learning and memory dysfunction. Euxanthone is a xanthone derivative obtained from Polygala caudata. This study was designed to investigate whether euxanthone can confer neuroprotective activities against sevoflurane-induced neurotoxicity and to determine the associated molecular mechanisms. Neonatal Sprague-Dawley (male) rats were exposed to sevoflurane with or without euxanthone treatment. The behavioral data of rats were collected at P41 (the beginning of the adult stage). The hippocampal tissue was obtained following exposure to sevoflurane. The reactive oxygen species (ROS) level in the hippocampal tissue was determined by a commercial kit. The expression of apoptotic markers and inflammatory cytokines was determined by western blot. The mRNA and protein expression of Nrf2 were determined by qRT-PCR and western blot, respectively. The rat in vitro model of neurotoxicity was established using isolated hippocampal neurons. Nrf2 expression was repressed by transfection of siRNA. The cell viability was assessed by the CCK-8 assay. The flow cytometry was performed to measure apoptotic cell death. Our data showed that euxanthone treatment at the neonatal stage protected against sevoflurane-induced neurotoxicity in adult rats. At the molecular level, our findings revealed that the neuroprotective activities of euxanthone were associated with decreased sevoflurane-induced apoptosis cell death and neuroinflammation. More importantly, our results provide the experimental evidence that euxanthone confers neuroprotection by upregulating Nrf2 expression. Euxanthone has a therapeutic potential for clinical prevention of sevoflurane-induced neurotoxicity.

Inhibition of protein tyrosine phosphatase 1B protects against sevoflurane-induced neurotoxicity mediated by ER stress in developing brain

BackgroundER stress is involved in sevoflurane-induced neurotoxicity. Protein tyrosine phosphatase 1B (PTP1B) resided in the ER membrane is known to regulate ER stress. However, the role of PTP1B in sevoflurane-induced neurotoxicity is unknown. MethodSeven-day-old mice treated with 2.3% sevoflurane for 6 h as animal model. The hippocampal tissues were harvested following sevoflurane exposure for evaluation of ER stress markers with Western blot, ER morphology with transmission electron microscopy and density of dendrite spine with Golgi staining. In another subset of mice, neurocognitive function was assessed 4 weeks after anesthesia using Morris water maze test. We also examined the effects of PTP1B or PERK inhibitor on sevoflurane-induced neurodegeneration in the hippocampus. ResultThe results showed inhibition of PTP1B significantly ameliorated sevoflurane-induced (1) ultrastructural ER alternations and ER stress activation as indicated by upregulation of PERK and eIF2α phosphorylation; (2) increase in cleaved caspase-3 expression; (3) elevated expressions of proinflammatory NF-κB and TNFα;(4) decreases in expression of synaptophysin, Arc and BDNF-TrkB proteins as well as loss of dendrite spine in the hippocampus; and (5) impairment in neurobehavioural performance at adolescence. Similarly, ER stress inhibitor is also found to downregulate eIF2α phosphorylation and neuroinflammation, and increase expressions of synaptic proteins and BDNF-TrkB signaling proteins. ConclusionsOur study shows PTP1B inhibition mitigates sevoflurane-induced neurodegeneration maybe mediated by ER stress in developing brain, and eventually improves cognitive function. This suggests PTP1B inhibition could represent a promising strategy to prevent sevoflurane-induced neurotoxicity.

Metformin protects against sevoflurane-induced neuronal apoptosis through the S1P1 and ERK signaling pathways.

The aim of the current study was to investigate whether metformin could counteract sevoflurane-induced neurotoxicity. In vitro experiments on the sevoflurane-induced nerve injury were performed using hippocampal neurons. Neuronal apoptosis was detected by an MTT assay. Protein expression levels of apoptosis-associated genes, including cleaved-caspase-3, apoptosis regulator BAX and apoptosis regulator Bcl-2 were detected by western blot analysis. The mechanism of the effect of metformin on sevoflurane-induced neuronal apoptosis was investigated using a sphingosine 1-phosphate receptor 1 (S1P1) antagonist (VPC23019) and mitogen-activated protein kinase kinase inhibitor (U0126). The current study revealed that metformin may reduce sevoflurane-induced neuronal apoptosis via activating mitogen-activated protein kinase (ERK)1/2 phosphorylation. VPC23019 and U0126 eliminated the neuroprotective effects of metformin on neuronal apoptosis, which suggests that metformin is able to protect against sevoflurane-induced neurotoxicity via activation of the S1P1-dependent ERK1/2 signaling pathway.

The role of Bag2 in neurotoxicity induced by the anesthetic sevoflurane.

Sevoflurane is the most commonly used general anesthetic in pediatric patients. But preclinical studies indicate that sevoflurane could have neurotoxicity in newborn and old animals, and this raises concern regarding its safety. In this study, we explored the potential mechanisms of sevoflurane-induced neurotoxicity in human SH-SY5Y neuronal cells. We showed that prolonged exposure to 2% sevoflurane caused a significant increase in the Bag family protein Bag2 in a time- and dose-dependent manner. We investigated the possible role of Bag2 upon exposure to sevoflurane by silencing Bag2 in neuronal cells. Knockdown of Bag2 caused increased overall reactive oxygen species (ROS) and generation of lipid peroxidation products 4-hydroxynonenal (4-HNE). Upon sevoflurane exposure, Bag2-silent cells have reduced glutathione (GSH) and glutathione peroxidase activity. Under the sevoflurane treatment, Bag2-deficient cells have reduced mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) production, while knockdown cells have less viability and higher lactic dehydrogenase (LDH) release as well as a higher percentage of apoptotic cells. The knockdown cells also had higher levels of mitochondrial cytochrome C release, a higher ratio of Bax/Bcl-2 and increased caspase cleavage by sevoflurane. Overall, our data support an important role of Bag2 in sevoflurane-induced neurotoxicity.

Role of autophagy in sevoflurane-induced neurotoxicity in neonatal rat hippocampal cells

BackgroundSevoflurane has been extensively employed for induction and maintenance of general anesthesia. The effect of sevoflurane-induced apoptosis in developmental neurotoxicity has been appreciated for some time now, but the underlying mechanism of developmental neurotoxicity has not been established. The aim of our study is to evaluate the role of autophagy in sevoflurane-induced neurotoxicity through observing changes in the levels of autophagy in hippocampal neurons after exposure to sevoflurane. Methods/MaterialsPrimary cultured hippocampus neuronal cells were exposed to either 3.4% sevoflurane for 1 h (S1h group), 3 h (S3h group), 5 h (S5h group), or air (control group). We observed changes in autophagy proteins Beclin-1, LC3-II, p62, and Beclin-1mRNA, LC3mRNA and SQSTM1mRNA using Western Blot and QRT-PCR. We also determined the expression of LC3 using immunofluorescence staining, monitored the occurrence of autophagy using RFP-GFP-LC3 expression plasmid transient transfected hippocampal neuronal cells, detected the expression of LC3-II using siRNA Knockdown Beclin-1 and Atg5, and determined changes in cell apoptosis using Annexin V/PI staining and flow cytometry. ResultsAfter primary cultured hippocampal neuronal cells were exposed to 3.4% sevoflurane for 5 h, the expression level of Beclin-1 and LC3-II increased and p62 decreased in Western blotting. The expression of Beclin-1mRNA, LC3mRNA increased and SQSTM1mRNA decreased in QRT-PCR. LC3 increased with cell immunofluorescence staining, LC3 expression plasmid increased after mRFP-GFP-LC3 expression plasmid transient transfection and LC3-II decreased after transfection with siRNA Beclin-1 and siRNA Atg5. The apoptosis rate of primary cultured hippocampal neuronal cells increased in Annexin V/PI staining and flow cytometry analysis. ConclusionThis study demonstrates that sevoflurane may induce hippocampal neuron autophagy in primary cultured hippocampal neuronal cell and that Beclin-1 and Atg5 are involved in the process of sevoflurane-induced autophagy. Exposure of sevoflurane may not only induce autophagy of hippocampal neurons but also activate the apoptosis of hippocampal neurons. Autophagy may play an important role in sevoflurane-induced neurotoxicity in primary cultured hippocampal neuronal cells.

Autophagy is involved in sevoflurane-induced developmental neurotoxicity in the developing rat brain

BackgroundSevoflurane can induce neonatal wide neurodegenerative and serious deficit to space learning tasks in rodents, however, the specific mechanism is still unclear. At present, the study tried to explore the possible role of autophagy in sevoflurane-induced neurotoxicity through observing the changes in the levels of autophagy in the newborn SD rat hippocampus tissue after sevoflurane exposure. MethodsWe used seventy-two SD rats of seven days receiving sevoflurane exposure to explore hippocampus neuron autophagy and apoptosis. ResultsOur results indicated that sevoflurane increased the levels of Beclin-1, microtubule-associated protein light chain 3II protein and decreased sequestosome 1 levels in a time-dependent manner by Western blot in the developing brain. These results were further substantiated by transmission electron microscopy, quantitative reverse transcription polymerase chain reaction, immunohistochemistry and immunofluorescence. Rapamycin, an activator of autophagy, increased the levels of Beclin-1and LC3-II protein, meanwhile, 3-methyladenine, an inhibitor of autophagy, decreased Beclin-1and LC3-II protein levels. ConclusionTaken together, autophagy may be involved in sevoflurane-induced developmental neurotoxicity and promoting protective autophagy may be a potential way of preventing developmental sevoflurane-induced neurotoxicity.

Upregulation of long noncoding RNA Gadd45a is associated with sevoflurane-induced neurotoxicity in rat neural stem cells.

Emerging evidence has shown that long noncoding RNA (lncRNA) plays a crucial role in controlling neural stem cells' (NSCs) survival. However, the fundamental role of lncRNA underlying sevoflurane-induced neurotoxicity remains poorly elucidated. In the present study, we investigate the effect of sevoflurane-induced neurotoxicity in a concentration-dependent and duration-dependent manner. Furthermore, we assayed the differential profile of lncRNA in rat hippocampal NSCs following sevoflurane exposure, and identified lncRNA Gadd45a and the correlation between lncRNA Gadd45a and Gadd45a. We found that lncRNA Gadd45a and its nearby gene, Gadd45a, were significantly upregulated in NSCs exposed to sevoflurane. Notably, Gadd45a was enriched in the cell cycle-relative pathway including mitogen-activated protein kinases and P53 signaling, whereas lncRNA Gadd45a was positively correlated with Gadd45a. These results suggest lncRNA Gadd45a is associated with sevoflurane-induced toxicity, and thus shed light on a new key target for revealing the molecular mechanism of sevoflurane-induced toxicity.

Elevated expression of DJ-1 (encoded by the human PARK7 gene) protects neuronal cells from sevoflurane-induced neurotoxicity.

Sevoflurane, an inhaled ether general anesthetic agent, exerts a variety of neurotoxic effects, including oxidative stress, mitochondrial dysfunction, and neuronal apoptosis. However, the underlying molecular mechanisms remain to be elucidated. DJ-1 is a protein that exerts neuroprotective effects against different kinds of stress through multiple pathways. This study aimed to investigate the neuroprotective effects of DJ-1 against sevoflurane-induced neurotoxicity. Here, we found that sevoflurane treatment significantly increased DJ-1 expression in human neuroblastoma M17 cells in a dose-dependent manner at both the mRNA and protein levels. Interestingly, we found that overexpression of wild-type (WT) DJ-1 prevented sevoflurane-induced generation of reactive oxygen species (ROS) and nitric oxide (NO), deletion of reduced GSH, reduction of adenosine triphosphate (ATP), and mitochondrial membrane potential. Interestingly, we found that WT DJ-1 could inhibit sevoflurane-induced apoptosis by modulating the mitochondrial pathway. However, its "loss of function" mutation DJ-1(L166P) exacerbated sevoflurane-induced neurotoxicity in M17 cells. Our findings suggest that WT DJ-1 protects neuronal cells against sevoflurane-induced neurotoxicity.

Effects of Sevoflurane Exposure During Mid-Pregnancy on Learning and Memory in Offspring Rats: Beneficial Effects of Maternal Exercise.

Fetal exposure to general anesthetics may pose significant neurocognitive risks but methods to mitigate against these detrimental effects are still to be determined. We set out, therefore, to assess whether single or repeated in utero exposure to sevoflurane triggers long-term cognitive impairments in rat offspring. Since maternal exercise during pregnancy has been shown to improve cognition in offspring, we hypothesized that maternal treadmill exercise during pregnancy would protect against sevoflurane-induced neurotoxicity. In the first experiment, pregnant rats were exposed to 3% sevoflurane for 2 h on gestational (G) day 14, or to sequential exposure for 2 h on G13, G14 and G15. In the second experiment, pregnant rats in the exercise group were forced to run on a treadmill for 60 min/day during the whole pregnancy. The TrkB antagonist ANA-12 was used to investigate whether the brain-derived neurotrophic factor (BDNF)/TrkB/Akt signaling pathway is involved in the neuroprotection afforded by maternal exercise. Our data suggest that repeated, but not single, exposure to sevoflurane caused a reduction in both histone acetylation and BDNF expression in fetal brain tissues and postnatal hippocampus. This was accompanied by decreased numbers of dendritic spines, impaired spatial-dependent learning and memory dysfunction. These effects were mitigated by maternal exercise but the TrkB antagonist ANA-12 abolished the beneficial effects of maternal exercise. Our findings suggest that repeated, but not single, exposure to sevoflurane in pregnant rats during the second trimester caused long-lasting learning and memory dysfunction in the offspring. Maternal exercise ameliorated the postnatal neurocognitive impairment by enhancing histone acetylation and activating downstream BDNF/TrkB/Akt signaling.

Hispidulin prevents sevoflurane— Induced memory dysfunction in aged rats

AimAs a widely used general anesthetic, sevoflurane has been found to induce cognitive and memory defectsin the elderly. This may increase the risk of Alzheimer’s disease. This study explores the neuroprotective effect of hispidulin, a natural flavone compound, against sevoflurane-induced memory dysfunction. MethodsThe effect of sevoflurane exposure on memory function was evaluated by novel object recognition and Y-maze testing using an aged rat model. The apoptotic cell death in the hippocampus of rats was assessed using a TUNEL assay. The levels of protein markers for cell apoptosis in the hippocampus were examined by western blot. The effect of sevoflurane and hispidulin on the accumulation of Aβ was also examined. In addition, the attenuating effect of hispidulin on sevoflurane-induced neuroinflammation was assessed by measuring the expression of pro-inflammatory cytokines and the translocation of NF-κB p65 from cytosol to nucleus. The activation of Nrf2 in the hippocampus was also detected. Moreover, the effect of hispidulin on sevoflurane-induced apoptosis, Aβ accumulation, and neuroinflammation was also examined in human neuroglioma H4 cells, which served as an in vitro model.To further examine the role of Nrf2 in the neuroprotective activity of hispidulin against sevoflurane-neurotoxicity, H4 cells were transfected with Nrf2 targeting siRNA, which led to a significant reduction in Nrf2 expression. ResultsBoth novel object recognition and Y-maze testing showed that sevoflurane significantly impaired the memory of aged rats, which was significantly reversed by pretreatment with hispidulin. Mechanistically, our findings revealed that hispidulin significantly attenuated sevoflurane-induced apoptotic cell death, Aβ accumulation, and neuroinflammation. In agreement with in vivo studies, hispidulin was also able to attenuate sevoflurane-induced apoptosis, increases of Aβ levels, and neuroinflammation in H4 cells. Moreover, our results showed that Nrf2 activation mediated the neuroprotective effect of hispidulin against sevoflurane-induced neurotoxicity by demonstrating that knockdown of Nrf2 in H4 cells significantly compromised its protective effects. ConclusionAs our study provides in vitro and in vivo evidence that hispidulin can offer protection against sevoflurane-induced neurological dysfunction, hispidulin has the potential to be a neuroprotective agent that can improve the cognitive and memory function of elderly patients undergoing anesthesia.

MicroRNA-27a-3p suppression of peroxisome proliferator-activated receptor-γ contributes to cognitive impairments resulting from sevoflurane treatment.

Sevoflurane is the most widely used anaesthetic administered by inhalation. Exposure to sevoflurane in neonatal mice can induce learning deficits and abnormal social behaviours. MicroRNA (miR)-27a-3p, a short, non-coding RNA that functions as a tumour suppressor, is up-regulated after inhalation of anaesthetic, and peroxisome proliferator-activated receptor γ (PPAR-γ) is one of its target genes. The objective of this study was to investigate how the miR-27a-3p-PPAR-γ interaction affects sevoflurane-induced neurotoxicity. A luciferase reporter assay was employed to identify the interaction between miR-27a-3p and PPAR-γ. Primary hippocampal neuron cultures prepared from embryonic day 0 C57BL/6 mice were treated with miR-27a-3p inhibitor or a PPAR-γ agonist to determine the effect of miR-27a-3p and PPAR-γ on sevoflurane-induced cellular damage. Cellular damage was assessed by a flow cytometry assay to detect apoptotic cells, immunofluorescence to detect reactive oxygen species, western blotting to detect NADPH oxidase 1/4 and ELISA to measure inflammatory cytokine levels. In vivo experiments were performed using a sevoflurane-induced anaesthetic mouse model to analyse the effects of miR-27a-3p on neurotoxicity by measuring the number of apoptotic neurons using the Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) method and learning and memory function by employing the Morris water maze test. Our results revealed that PPAR-γ expression was down-regulated by miR-27a-3p following sevoflurane treatment in hippocampal neurons. Down-regulation of miR-27a-3p expression decreased sevoflurane-induced hippocampal neuron apoptosis by decreasing inflammation and oxidative stress-related protein expression through the up-regulation of PPAR-γ. In vivo tests further confirmed that inhibition of miR-27a-3p expression attenuated sevoflurane-induced neuronal apoptosis and learning and memory impairment. Our findings suggest that down-regulation of miR-27a-3p expression ameliorated sevoflurane-induced neurotoxicity and learning and memory impairment through the PPAR-γ signalling pathway. MicroRNA-27a-3p may, therefore, be a potential therapeutic target for preventing or treating sevoflurane-induced neurotoxicity.

Dexmedetomidine-mediated neuroprotection against sevoflurane-induced neurotoxicity extends to several brain regions in neonatal rats

BackgroundExposure of infant animals to clinically used anaesthetics is associated with acute structural brain abnormalities and development functional alterations. The α2-adrenoceptor agonist dexmedetomidine (DEX) induces sedation, analgesia, and provides neuroprotection in experimental brain injury models. However, it is unknown whether DEX also affords protection in the developing brain against anaesthesia using sevoflurane (SEVO), which is commonly used in paediatric anaesthesia. MethodsInfant rats were exposed on postnatal day seven for six h to 2.5% SEVO and were given i.p. injections of saline or DEX (1–50 µg kg−1) three times during the exposure. Level of anaesthesia, respiratory rates, and arterial blood gasses were assessed for each animal. Apoptosis was determined in brain slices immunostained for activated caspase-3 (AC-3) using a computerised approach. ResultsSEVO alone induced a surgical plane of anaesthesia, and all animals survived the study. SEVO induced an approximately 10-fold increase in AC-3 positive cells in several cortical and subcortical brain regions compared with untreated control animals. Co-administration of DEX 1 µg kg−1 with SEVO significantly reduced apoptosis in all brain areas, affording the highest protection in the thalamus (84% reduction) and lowest in the hippocampus and cortical areas (∼50% reduction). DEX 5–25 µg kg−1 plus SEVO dose-dependently increased infant rat mortality. ConclusionsSEVO anaesthesia induced widespread apoptosis in infant rat brain. Co-administration of DEX (1 µg kg−1) provided significant protection, whereas DEX (5 µg kg−1 or higher) plus SEVO increased mortality. Our findings suggest that DEX could be an attractive therapeutic for future studies investigating its neuroprotective potential in a translational animal model.

Protective effects of a green tea polyphenol, epigallocatechin-3-gallate, against sevoflurane-induced neuronal apoptosis involve regulation of CREB/BDNF/TrkB and PI3K/Akt/mTOR signalling pathways in neonatal mice.

Epigallocatechin-3-gallate (EGCG), a polyphenol in green tea, is an effective antioxidant and possesses neuroprotective effects. Brain-derived neurotrophic factor (BDNF) and cyclic AMP response element-binding protein (CREB) are crucial for neurogenesis and synaptic plasticity. In this study, we aimed to assess the protective effects of EGCG against sevoflurane-induced neurotoxicity in neonatal mice. Distinct groups of C57BL/6 mice were given EGCG (25, 50, or 75 mg/kg body weight) from postnatal day 3 (P3) to P21 and were subjected to sevoflurane (3%; 6 h) exposure on P7. EGCG significantly inhibited sevoflurane-induced neuroapoptosis as determined by Fluoro-Jade B staining and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL). Increased levels of cleaved caspase-3, downregulated Bad and Bax, and significantly enhanced Bcl-2, Bcl-xL, xIAP, c-IAP-1, and survivin expression were observed. EGCG induced activation of the PI3K/Akt pathway as evidenced by increased Akt, phospho-Akt, GSK-3β, phospho-GSK-3β, and mTORc1 levels. Sevoflurane-mediated downregulation of cAMP/CREB and BDNF/TrkB signalling was inhibited by EGCG. Reverse transcription PCR analysis revealed enhanced BDNF and TrkB mRNA levels upon EGCG administration. Improved performance of mice in Morris water maze tests suggested enhanced learning and memory. The study indicates that EGCG was able to effectively inhibit sevoflurane-induced neurodegeneration and improve learning and memory retention of mice via activation of CREB/BDNF/TrkB-PI3K/Akt signalling.

Tanshinone IIA Attenuates Sevoflurane Neurotoxicity in Neonatal Mice.

Sevoflurane is the most widely used inhalational anesthetic in pediatric medicine. Despite this, sevoflurane has been reported to exert potentially neurotoxic effects on the developing brain. Clinical interventions and treatments for these effects are limited. Tanshinone IIA (Tan IIA), extracted from Salvia miltiorrhiza (Danshen), has been documented to alleviate cognitive decline in traditional applications. Therefore, we hypothesized that preadministration of Tan IIA may attenuate sevoflurane-induced neurotoxicity, suggesting that Tan IIA is a new and promising drug capable of counteracting the effects of cognitive dysfunction produced by general anesthetics. To test this hypothesis, neonatal C57 mice (P6) were exposed to 3% sevoflurane for 2 hours with or without Tan IIA pretreatment at a dose of 10 mg/kg or 20 mg/kg for 3 consecutive days. Cognitive behavior tests such as open field tests and fear conditioning were performed to evaluate locomotor and cognitive function at P31 and P32. At P8, other separate tests, including TdT mediated dUTP Nick End Labeling (TUNEL) assay, immunohistochemistry, Western blotting, enzyme-linked immunosorbent assay, and electron microscopy, were performed. The mean differences among groups were compared using 1-way analysis of variance followed by Bonferroni post hoc multiple comparison tests. Repeated exposure to sevoflurane leads to significant cognitive impairment in mice, which may be explained by increased apoptosis, overexpression of neuroinflammatory markers, and changes in synaptic ultrastructure. Interestingly, preadministration of Tan IIA ameliorated these neurocognitive deficits, as shown by increased freezing percentages on the fear conditioning test (sevoflurane+Tan IIA [20 mg/kg] versus sevoflurane, mean difference, 19, 99% confidence interval for difference, 6.4-31, P < .0001, n = 6). The treatment also reduced the percentage of TUNEL-positive nuclei (sevoflurane versus sevoflurane+Tan IIA [20 mg/kg], 2.6, 0.73-4.5, P = .0004, n = 6) and the normalized expression of cleaved caspase-3 (sevoflurane versus sevoflurane+Tan IIA [20 mg/kg], 0.27, 0.02-0.51, P = .0046, n = 5). Moreover, it attenuated the production of the neuroinflammatory mediators interleukin (IL)-1β and IL-6 (normalized sevoflurane versus sevoflurane+Tan IIA [20 mg/kg]: IL-1β: 0.75, 0.47-1.0; P < .0001; IL-6: 0.66, 0.35-0.97; P < .0001; n = 10 per group). Finally, based on measurements of postsynaptic density, the treatment preserved synaptic ultrastructure (sevoflurane+Tan IIA [20 mg/kg] versus sevoflurane, 42, 20-66; P < .0001; n = 12 per group). These results indicate that Tan IIA can alleviate sevoflurane-induced neurobehavioral abnormalities and may decrease neuroapoptosis and neuroinflammation.

Maternal Sevoflurane Exposure Causes Abnormal Development of Fetal Prefrontal Cortex and Induces Cognitive Dysfunction in Offspring.

Maternal sevoflurane exposure during pregnancy is associated with increased risk for behavioral deficits in offspring. Several studies indicated that neurogenesis abnormality may be responsible for the sevoflurane-induced neurotoxicity, but the concrete impact of sevoflurane on fetal brain development remains poorly understood. We aimed to investigate whether maternal sevoflurane exposure caused learning and memory impairment in offspring through inducing abnormal development of the fetal prefrontal cortex (PFC). Pregnant mice at gestational day 15.5 received 2.5% sevoflurane for 6 h. Learning function of the offspring was evaluated with the Morris water maze test at postnatal day 30. Brain tissues of fetal mice were subjected to immunofluorescence staining to assess differentiation, proliferation, and cell cycle dynamics of the fetal PFC. We found that maternal sevoflurane anesthesia impaired learning ability in offspring through inhibiting deep-layer immature neuron output and neuronal progenitor replication. With the assessment of cell cycle dynamics, we established that these effects were mediated through cell cycle arrest in neural progenitors. Our research has provided insights into the cell cycle-related mechanisms by which maternal sevoflurane exposure can induce neurodevelopmental abnormalities and learning dysfunction and appeals people to consider the neurotoxicity of anesthetics when considering the benefits and risks of nonobstetric surgical procedures.

Altered hippocampal microRNA expression profiles in neonatal rats caused by sevoflurane anesthesia: MicroRNA profiling and bioinformatics target analysis

Although accumulating evidence has suggested that microRNAs (miRNAs) have a serious impact on cognitive function and are associated with the etiology of several neuropsychiatric disorders, their expression in sevoflurane-induced neurotoxicity in the developing brain has not been characterized. In the present study, the miRNAs expression pattern in neonatal hippocampus samples (24 h after sevoflurane exposure) was investigated and 9 miRNAs were selected, which were associated with brain development and cognition in order to perform a bioinformatic analysis. Previous microfluidic chip assay had detected 29 upregulated and 24 downregulated miRNAs in the neonatal rat hippocampus, of which 7 selected deregulated miRNAs were identified by the quantitative polymerase chain reaction. A total of 85 targets of selected deregulated miRNAs were analyzed using bioinformatics and the main enriched metabolic pathways, mitogen-activated protein kinase and Wnt pathways may have been involved in molecular mechanisms with regard to neuronal cell body, dendrite and synapse. The observations of the present study provided a novel understanding regarding the regulatory mechanism of miRNAs underlying sevoflurane-induced neurotoxicity, therefore benefitting the improvement of the prevention and treatment strategies of volatile anesthetics related neurotoxicity.

Aberrantly expressed long noncoding RNAs are involved in sevoflurane-induced developing hippocampal neuronal apoptosis: a microarray related study.

The commonly used volatile anesthetic sevoflurane has been shown to induce widespread apoptosis in the developing brain, yet the underlying molecular mechanisms are not fully understood. Accumulating research has demonstrated that long noncoding RNAs (lncRNAs) regulate multiple biological processes, including neural development, differentiation and apoptosis. They are aberrantly expressed in multiple neurodegenerative diseases. In this study, we employed a lncRNA-mRNA microarray analysis to determine whether and how lncRNAs are involved in sevoflurane-induced hippocampal neuronal apoptosis in neonatal mice. Our data showed that a single 6-h sevoflurane exposure of P7 mice resulted in significant morphological changes and apoptosis in the hippocampus. Moreover, the microarray simultaneously revealed 817 lncRNAs and 856 of their potential coding targets that related to apoptosis, of which 31 lncRNAs (19 up and 12 down) and 25 mRNAs were significantly differentially expressed (P<0.05) after sevoflurane exposure. Importantly, we found that Bcl2l11 (BIM), which potentiates mitochondria-dependent apoptosis and its nearby enhancer-like lncRNA ENSMUST00000136025, were both more highly expressed in sevoflurane-treated samples compared with control samples. Subsequent qRT-PCR results confirmed the changes. Further CNC network indicated that lncRNA ENSMUST00000136025 was positively correlated with Bim. Moreover, sevoflurane induced a significant increase of pro-apoptotic protein BIM and Bax but a reduction of anti-apoptotic proteins Bcl-2 in the hippocampus. Our study first demonstrates that aberrantly expressed lncRNAs play a role in sevoflurane-induced hippocampal apoptosis. We noted that up-regulated ENSMUST00000136025 highly likely induced the over-expression of BIM, which eventually promoted mitochondria-mediated apoptosis. Such findings further broaden the understanding of molecular mechanisms responsible for sevoflurane-induced neurotoxicity.