Modulatory dynamics mark the transition between anesthetic states of unconsciousness.

Unconsciousness maintained by GABAergic anesthetics, such as propofol and sevoflurane, is characterized by slow-delta oscillations (0.3 to 4 Hz) and alpha oscillations (8 to 14 Hz) that are readily visible in the electroencephalogram. At higher doses, these slow-delta-alpha (SDA) oscillations transition into burst suppression. This is a marker of a state of profound brain inactivation during which isoelectric (flatline) periods alternate with periods of the SDA patterns present at lower doses. While the SDA and burst suppression patterns have been analyzed separately, the transition from one to the other has not. Using state-space methods, we characterize the dynamic evolution of brain activity from SDA to burst suppression and back during unconsciousness maintained with propofol or sevoflurane in volunteer subjects and surgical patients. We uncover two dynamical processes that continuously modulate the SDA oscillations: alpha-wave amplitude and slow-wave frequency modulation. We present an alpha modulation index and a slow modulation index which characterize how these processes track the transition from SDA oscillations to burst suppression and back to SDA oscillations as a function of increasing and decreasing anesthetic doses, respectively. Our biophysical model reveals that these dynamics track the combined evolution of the neurophysiological and metabolic effects of a GABAergic anesthetic on brain circuits. Our characterization of the modulatory dynamics mediated by GABAergic anesthetics offers insights into the mechanisms of these agents and strategies for monitoring and precisely controlling the level of unconsciousness in patients under general anesthesia.

Identification of differential m6A RNA methylomes and ALKBH5 as a potential prevention target in the developmental neurotoxicity induced by multiple sevoflurane exposures.

Sevoflurane, as a commonly used inhaled anesthetic for pediatric patients, has been reported that multiple sevoflurane exposures are associated with a greater risk of developing neurocognitive disorder. N6-Methyladenosine (m6A), as the most common mRNA modification in eukaryotes, has emerged as a crucial regulator of brain function in processes involving synaptic plasticity, learning and memory, and neurodevelopment. Nevertheless, the relevance of m6A RNA methylation in the multiple sevoflurane exposure-induced developmental neurotoxicity remains mostly elusive. Herein, we evaluated the genome-wide m6A RNA modification and gene expression in hippocampus of mice that received with multiple sevoflurane exposures using m6A-sequencing (m6A-seq) and RNA-sequencing (RNA-seq). We discovered 19 genes with differences in the m6A methylated modification and differential expression in the hippocampus. Among these genes, we determined that a total of nine differential expressed genes may be closely associated with the occurrence of developmental neurotoxicity induced by multiple sevoflurane exposures. We further found that the alkB homolog 5 (ALKBH5), but not methyltransferase-like 3 (METTL3) and Wilms tumor 1-associated protein (WTAP), were increased in the hippocampus of mice that received with multiple sevoflurane exposures. And the IOX1, as an inhibitor of ALKBH5, significantly improved the learning and memory defects and reduced neuronal damage in the hippocampus of mice induced by multiple sevoflurane exposures. The current study revealed the role of m6A methylated modification and m6A-related regulators in sevoflurane-induced cognitive impairment, which might provide a novel insight into identifying biomarkers and therapeutic strategies for inhaled anesthetic-induced developmental neurotoxicity.

Effects of sevoflurane on lung alveolar epithelial wound healing and survival in a sterile in vitro model of acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a serious lung condition that often leads to hospitalization in intensive care units and a high mortality rate. Sevoflurane is a volatile anesthetic with growing interest for sedation in ventilated patients with ARDS. It has been shown to have potential lung-protective effects, such as reduced inflammation and lung edema, or improved arterial oxygenation. In this study, we investigated the effects of sevoflurane on lung injury in cultured human carcinoma-derived lung alveolar epithelial (A549) cells. We found that sevoflurane was associated with improved wound healing after exposure to inflammatory cytokines, with preserved cell proliferation but no effect on cell migration properties. Sevoflurane exposure was also associated with enhanced cell viability and active autophagy in A549 cells exposed to cytokines. These findings suggest that sevoflurane may have beneficial effects on lung epithelial injury by promoting alveolar epithelial wound healing and by influencing the survival and proliferation of A549 epithelial cells in vitro. Further research is needed to confirm these findings and to investigate the key cellular mechanisms explaining sevoflurane's potential effects on lung epithelial injury.

Decreased Thalamic Activity Is a Correlate for Disconnectedness during Anesthesia with Propofol, Dexmedetomidine and Sevoflurane But Not S-Ketamine.

Establishing the neural mechanisms responsible for the altered global states of consciousness during anesthesia and dissociating these from other drug-related effects remains a challenge in consciousness research. We investigated differences in brain activity between connectedness and disconnectedness by administering various anesthetics at concentrations designed to render 50% of the subjects unresponsive. One hundred and sixty healthy male subjects were randomized to receive either propofol (1.7 µg/ml; n = 40), dexmedetomidine (1.5 ng/ml; n = 40), sevoflurane (0.9% end-tidal; n = 40), S-ketamine (0.75 µg/ml; n = 20), or saline placebo (n = 20) for 60 min using target-controlled infusions or vaporizer with end-tidal monitoring. Disconnectedness was defined as unresponsiveness to verbal commands probed at 2.5-min intervals and unawareness of external events in a postanesthesia interview. High-resolution positron emission tomography (PET) was used to quantify regional cerebral metabolic rates of glucose (CMRglu) utilization. Contrasting scans where the subjects were classified as connected and responsive versus disconnected and unresponsive revealed that for all anesthetics, except S-ketamine, the level of thalamic activity differed between these states. A conjunction analysis across the propofol, dexmedetomidine and sevoflurane groups confirmed the thalamus as the primary structure where reduced metabolic activity was related to disconnectedness. Widespread cortical metabolic suppression was observed when these subjects, classified as either connected or disconnected, were compared with the placebo group, suggesting that these findings may represent necessary but alone insufficient mechanisms for the change in the state of consciousness.SIGNIFICANCE STATEMENT Experimental anesthesia is commonly used in the search for measures of brain function which could distinguish between global states of consciousness. However, most previous studies have not been designed to separate effects related to consciousness from other effects related to drug exposure. We employed a novel study design to disentangle these effects by exposing subjects to predefined EC50 doses of four commonly used anesthetics or saline placebo. We demonstrate that state-related effects are remarkably limited compared with the widespread cortical effects related to drug exposure. In particular, decreased thalamic activity was associated with disconnectedness with all used anesthetics except for S-ketamine.

The effect of sevoflurane exposure on cell-type-specific changes in the prefrontal cortex in young mice.

Sevoflurane, the predominant pediatric anesthetic, has been linked to neurotoxicity in young mice, although the underlying mechanisms remain unclear. This study focuses on investigating the impact of neonatal sevoflurane exposure on cell-type-specific alterations in the prefrontal cortex (PFC) of young mice. Neonatal mice were subjected to either control treatment (60% oxygen balanced with nitrogen) or sevoflurane anesthesia (3% sevoflurane in 60% oxygen balanced with nitrogen) for 2 hours on postnatal days (PNDs) 6, 8, and 10. Behavioral tests and single-nucleus RNA sequencing (snRNA-seq) of the PFC were conducted from PNDs 31 to 37. Mechanistic exploration included clustering analysis, identification of differentially expressed genes (DEGs), enrichment analyses, single-cell trajectory analysis, and genome-wide association studies (GWAS). Sevoflurane anesthesia resulted in sociability and cognition impairments in mice. Novel specific marker genes identified 8 distinct cell types in the PFC. Most DEGs between the control and sevoflurane groups were unique to specific cell types. Re-defining 15 glutamatergic neuron subclusters based on layer identity revealed their altered expression profiles. Notably, sevoflurane disrupted the trajectory from oligodendrocyte precursor cells (OPCs) to oligodendrocytes (OLs). Validation of disease-relevant candidate genes across the main cell types demonstrated their association with social dysfunction and working memory impairment. Behavioral results and snRNA-seq collectively elucidated the cellular atlas in the PFC of young male mice, providing a foundation for further mechanistic studies on developmental neurotoxicity induced by anesthesia.

Laminar evoked responses in mouse somatosensory cortex suggest a special role for deep layers in cortical complexity.

It has been suggested that consciousness is closely related to the complexity of the brain. The perturbational complexity index (PCI) has been used in humans and rodents to distinguish conscious from unconscious states based on the global cortical responses (recorded by electroencephalography, EEG) to local cortical stimulation (CS). However, it is unclear how different cortical layers respond to CS and contribute to the resulting intra- and inter-areal cortical connectivity and PCI. A detailed investigation of the local dynamics is needed to understand the basis for PCI. We hypothesized that the complexity level of global cortical responses (PCI) correlates with layer-specific activity and connectivity. We tested this idea by measuring global cortical dynamics and layer-specific activity in the somatosensory cortex (S1) of mice, combining cortical electrical stimulation in deep motor cortex, global electrocorticography (ECoG) and local laminar recordings from layers 1-6 in S1, during wakefulness and general anaesthesia (sevoflurane). We found that the transition from wake to sevoflurane anaesthesia correlated with a drop in both the global and local PCI (PCIst ) values (complexity). This was accompanied by a local decrease in neural firing rate, spike-field coherence and long-range functional connectivity specific to deep layers (L5, L6). Our results suggest that deep cortical layers are mechanistically important for changes in PCI and thereby for changes in the state of consciousness.

Dexmedetomidine alleviates hippocampal neuronal loss and cognitive decline in rats undergoing open surgery under sevoflurane anaesthesia by suppressing CCAAT/enhancer-binding protein beta.

Dexmedetomidine (Dex) may exert neuroprotective effects by attenuating inflammatory responses. However, whether Dex specifically improves postoperative cognitive dysfunction (POCD) by inhibiting microglial inflammation through what pathway remains unclear. In this study, the POCD model was constructed by performing open surgery after 3 h of continuous inhalation of 3% sevoflurane to rats, which were intraperitoneally injected with 25 µg/kg Dex .5 h before anaesthesia. The results displayed that Dex intervention decreased rat escape latency, maintained swimming speed and increased the number of times rats crossed the platform and the time spent in the target quadrant. Furthermore, the rat neuronal injury was restored, alleviated POCD modelling-induced rat hippocampal microglial activation and inhibited microglial M1 type polarization. Besides, we administered Dex injection and/or CCAAT/enhancer-binding protein beta (CEBPB) knockdown on the basis of sevoflurane exposure and open surgery and found that CEBPB was knocked down, resulting in the inability of Dex to function, which confirmed CEBPB as a target for Dex treatment. To sum up, Dex improved POCD by considering CEBPB as a drug target to activate the c-Jun N-terminal kinase (JNK)/p-38 signaling pathway, inhibiting microglial M1 polarization-mediated inflammation in the central nervous system.

Overexpression of SESN1 improves mitochondrial damage and mitophagy, a potential therapeutic strategy for cognitive dysfunction after anaesthesia.

Postoperative cognitive dysfunction (POCD) is a prevalent central nervous system complication predominantly observed in elderly patients. Sevoflurane, a general anaesthetic agent, has been implicated in the development of POCD, yet the underlying regulatory mechanisms potentially involving Sestrin1 (SESN1), a stress-responsive protein that plays a critical role in cellular homeostasis and protection against stress-induced damage, including oxidative stress and DNA damage, remain elusive. This study endeavoured to elucidate the impact of SESN1 on sevoflurane-induced cognitive impairment in rats. Employing a model in which SESN1 was transfected into SD male rats and cognitive dysfunction was induced by sevoflurane. The Morris Water Maze test was used for behavioural evaluation, Enzyme-Linked Immunosorbent Assay, Western blotting and immunofluorescence were applied to assess the influence of SESN1 on the inflammatory response and mitophagy in the rat hippocampus. The study further aimed to uncover the putative mechanism by which SESN1, through SIRT1, might modulate cognitive function. Concurrently, levels of malondialdehyde, superoxide dismutase and mitochondrially produced ATP within the rat hippocampus were quantified. Experimental outcomes suggested that SESN1 overexpression significantly mitigated the deleterious effects of sevoflurane anaesthesia, ameliorated neuroinflammation and inflammasome activation, modified mitochondrial function and facilitated mitophagy. Additionally, SESN1, via the activation of SIRT1, may suppress inflammasome activation and mitochondrial dysfunction. Collectively, these findings underscore SESN1's integral role in counteracting sevoflurane-induced cognitive impairment, impeding inflammasome activation, enhancing mitochondrial function and fostering mitophagy, which appear to be intricately linked to SESN1-mediated SIRT1 activation. SESN1 is a novel therapeutic target for POCD, potentially advancing neuroprotective strategies in clinical settings.

Involvement of Fgf2-mediated tau protein phosphorylation in cognitive deficits induced by sevoflurane in aged rats.

OBJECTIVE: Anesthetics have been linked to cognitive alterations, particularly in the elderly. The current research delineates how Fibroblast Growth Factor 2 (Fgf2) modulates tau protein phosphorylation, contributing to cognitive impairments in aged rats upon sevoflurane administration. METHODS: Rats aged 3, 12, and 18 months were subjected to a 2.5% sevoflurane exposure to form a neurotoxicity model. Cognitive performance was gauged, and the GEO database was employed to identify differentially expressed genes (DEGs) in the 18-month-old cohort post sevoflurane exposure. Bioinformatics tools, inclusive of STRING and GeneCards, facilitated detailed analysis. Experimental validations, both in vivo and in vitro, examined Fgf2's effect on tau phosphorylation. RESULTS: Sevoflurane notably altered cognitive behavior in older rats. Out of 128 DEGs discerned, Fgf2 stood out as instrumental in regulating tau protein phosphorylation. Sevoflurane exposure spiked Fgf2 expression in cortical neurons, intensifying tau phosphorylation via the PI3K/AKT/Gsk3b trajectory. Diminishing Fgf2 expression correspondingly curtailed tau phosphorylation, neurofibrillary tangles, and enhanced cognitive capacities in aged rats. CONCLUSION: Sevoflurane elicits a surge in Fgf2 expression in aging rats, directing tau protein phosphorylation through the PI3K/AKT/Gsk3b route, instigating cognitive aberrations.

Sevoflurane blocks KLF5-mediated transcriptional activation of ITGB2 to inhibit macrophage infiltration in hepatic ischemia/reperfusion injury.

BACKGROUND: Sevoflurane (Sevo) preconditioning and postconditioning play a protective role against injury induced by hepatic ischemia/reperfusion (I/R). At the same time, the involvement of macrophage infiltration in this process and the precise mechanisms are unclear. Here, we designed this research to elucidate the protective effects of Sevo against hepatic I/R injury and the molecules involved. METHODS: The alleviating effect of Sevo on the liver injury was analyzed by liver function analysis, hematoxylin and eosin staining, Masson trichrome staining, terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling, western blot analysis and an enzyme-linked immunosorbent assay. An in vitro cell model was developed using alpha mouse liver 12 (AML12) cells, and the cell model was treated with oxygen-glucose deprivation and reoxygenation and Sevo. Multiple bioinformatics databases were used to screen transcriptional regulators related to hepatic I/R injury and the targets of Krueppel-like factor 5 (KLF5). KLF5 expression was artificially upregulated alone or with integrin beta-2 (ITGB2) knockdown to substantiate their involvement in Sevo-mediated hepatoprotection. RESULTS: Sevo protected the liver against I/R injury by reducing cell apoptosis and inflammatory response. KLF5 was upregulated in liver tissues following I/R injury, whereas KLF5 overexpression aggravated macrophage infiltration and liver injury induced by I/R injury. KLF5 bound to the promoter of ITGB2 to enhance ITGB2 transcription. Knockdown of ITGB2 reversed the aggravation of injury caused by KLF5 overexpression in mice and AML12 cells. CONCLUSIONS: Sevo blocked KLF5-mediated transcriptional activation of ITGB2, thereby inhibiting macrophage infiltration in hepatic I/R injury.

Histone deacetylase 9 plays a role in sevoflurane-induced neuronal differentiation inhibition by inactivating cAMP-response element binding protein transcription and inhibiting the expression of neurotrophin-3.

Postoperative cognitive decline (POCD) is a common and serious complication following anesthesia and surgery; however, the precise mechanisms of POCD remain unclear. Our previous research showed that sevoflurane impairs adult hippocampal neurogenesis (AHN) and thus cognitive function in the aged brain by affecting neurotrophin-3 (NT-3) expression; however, the signaling mechanism involved remains unexplored. In this study, we found a dramatic decrease in the proportion of differentiated neurons with increasing concentrations of sevoflurane, and the inhibition of neural stem cell differentiation was partially reversed after the administration of exogenous NT-3. Understanding the molecular underpinnings by which sevoflurane affects NT-3 is key to counteracting cognitive dysfunction. Here, we report that sevoflurane administration for 2 days resulted in upregulation of histone deacetylase 9 (HDAC9) expression, which led to transcriptional inactivation of cAMP-response element binding protein (CREB). Due to the colocalization of HDAC9 and CREB within cells, this may be related to the interaction between HDAC9 and CREB. Anyway, this ultimately led to reduced NT-3 expression and inhibition of neural stem cell differentiation. Furthermore, knockdown of HDAC9 rescued the transcriptional activation of CREB after sevoflurane exposure, while reversing the downregulation of NT-3 expression and inhibition of neural stem cell differentiation. In summary, this study identifies a unique mechanism by which sevoflurane can inhibit CREB transcription through HDAC9, and this process reduces NT-3 levels and ultimately inhibits neuronal differentiation. This finding may reveal a new strategy to prevent sevoflurane-induced neuronal dysfunction.

Liproxstatin-1 alleviates ferroptosis in sevoflurane anesthesia-induced cognitive deficits of aged mice: The role oxidative stress.

In this study, we aimed to validate the hypothesis that the interplay between sevoflurane, oxidative stress and ferroptosis is crucial for the pathogenesis of sevoflurane-induced cognitive impairment in aged individuals. The mice with sevoflurane-induced cognitive impairment were used to explore the effects of sevoflurane on oxidative stress, iron homeostasis, and cognitive function in aged mice. Iron content and oxidative stress markers were analyzed in hippocampal tissue homogenates using specific assays. Additionally, the levels of iron death-related markers (Fth1 and Gpx4) were assessed by real-time PCR and Western blotting. Morris Water Maze and novel object recognition (NOR) tests were conducted to evaluate cognitive function. Sevoflurane exposure in aged mice resulted in a significant increase in iron overloading in the hippocampus, followed by a subsequent stabilization. Oxidative stress levels were elevated in the hippocampal tissue of sevoflurane-exposed mice, and a significant correlation was observed between iron death and oxidative stress. Liproxstatin-1, a ferroptosis inhibitor, effectively ameliorated the decline in memory and learning abilities induced by sevoflurane anesthesia. Liproxstatin-1 treatment reduced iron overload and oxidative stress in the hippocampal tissue of aged mice. The expression of Fth1 and Gpx4, iron death-related markers, was downregulated following Liproxstatin-1 intervention. Our findings suggest that sevoflurane anesthesia disrupts iron homeostasis, leading to increased oxidative stress and cognitive impairment in aged mice. These results highlight the potential of targeting iron-mediated processes to mitigate sevoflurane-induced cognitive impairment in the aging population.

Topographical Features of Pediatric Electroencephalography during High Initial Concentration Sevoflurane for Inhalational Induction of Anesthesia.

BACKGROUND: High-density electroencephalographic (EEG) monitoring remains underutilized in clinical anesthesia, despite its obvious utility in unraveling the profound physiologic impact of these agents on central nervous system functioning. In school-aged children, the routine practice of rapid induction with high concentrations of inspiratory sevoflurane is commonplace, given its favorable efficacy and tolerance profile. However, few studies investigate topographic EEG during the critical timepoint coinciding with loss of responsiveness-a key moment for anesthesiologists in their everyday practice. The authors hypothesized that high initial sevoflurane inhalation would better precipitate changes in brain regions due to inhomogeneities in maturation across three different age groups compared with gradual stepwise paradigms utilized by other investigators. Knowledge of these changes may inform strategies for agent titration in everyday clinical settings. METHODS: A total of 37 healthy children aged 5 to 10 yr underwent induction with 4% or greater sevoflurane in high-flow oxygen. Perturbations in anesthetic state were investigated in 23 of these children using 64-channel EEG with the Hjorth Laplacian referencing scheme. Topographical maps illustrated absolute, relative, and total band power across three age groups: 5 to 6 yr (n = 7), 7 to 8 yr (n = 8), and 9 to 10 yr (n = 8). RESULTS: Spectral analysis revealed a large shift in total power driven by increased delta oscillations. Well-described topographic patterns of anesthesia, e.g., frontal predominance, paradoxical beta excitation, and increased slow activity, were evident in the topographic maps. However, there were no statistically significant age-related changes in spectral power observed in a midline electrode subset between the groups when responsiveness was lost compared to the resting state. CONCLUSIONS: High initial concentration sevoflurane induction causes large-scale topographic effects on the pediatric EEG. Within the minute after unresponsiveness, this dosage may perturb EEG activity in children to an extent where age-related differences are not discernible.

Medial Septal Glutamatergic Neurons Modulate States of Consciousness during Sevoflurane Anesthesia in Mice.

BACKGROUND: Multiple neural structures involved in maintaining wakefulness have been found to promote arousal from general anesthesia. The medial septum is a critical region that modulates arousal behavior. This study hypothesized that glutamatergic neurons in the medial septum play a crucial role in regulating states of consciousness during sevoflurane general anesthesia. METHODS: Adult male mice were used in this study. The effects of sevoflurane anesthesia on neuronal activity were determined by fiber photometry. Lesions and chemogenetic manipulations were used to study the effects of the altered activity of medial septal glutamatergic neurons on anesthesia induction, emergence, and sensitivity to sevoflurane. Optogenetic stimulation was used to observe the role of acute activation of medial septal glutamatergic neurons on cortical activity and behavioral changes during sevoflurane-induced continuous steady state of general anesthesia and burst suppression state. RESULTS: The authors found that medial septal glutamatergic neuronal activity decreased during sevoflurane anesthesia induction and recovered in the early period of emergence. Chemogenetic activation of medial septal glutamatergic neurons prolonged the induction time (mean ± SD, hM3Dq-clozapine N-oxide vs. hM3Dq-saline, 297.5 ± 60.1 s vs. 229.4 ± 29.9 s, P < 0.001, n = 11) and decreased the emergence time (53.2 ± 11.8 s vs. 77.5 ± 33.5 s, P = 0.025, n = 11). Lesions or chemogenetic inhibition of these neurons produced the opposite effects. During steady state of general anesthesia and deep anesthesia-induced burst suppression state, acute optogenetic activation of medial septal glutamatergic neurons induced cortical activation and behavioral emergence. CONCLUSIONS: The study findings reveal that activation of medial septal glutamatergic neurons has arousal-promoting effects during sevoflurane anesthesia in male mice. The activation of these neurons prolongs the induction and accelerates the emergence of anesthesia.

Stress Pathways Induced by Volatile Anesthetics and Failure of Preconditioning in a Mitochondrial Complex I Mutant.

BACKGROUND: Carriers of mutations in the mitochondrial electron transport chain are at increased risk of anesthetic-induced neurotoxicity. To investigate the neurotoxicity mechanism and to test preconditioning as a protective strategy, this study used a Drosophila melanogaster model of Leigh syndrome. Model flies carried a mutation in ND23 (ND2360114) that encodes a mitochondrial electron transport chain complex I subunit. This study investigated why ND2360114 mutants become susceptible to lethal, oxygen-modulated neurotoxicity within 24 h of exposure to isoflurane but not sevoflurane. METHODS: This study used transcriptomics and quantitative real-time reverse transcription polymerase chain reaction to identify genes that are differentially expressed in ND2360114 but not wild-type fly heads at 30 min after exposure to high- versus low-toxicity conditions. This study also subjected ND2360114 flies to diverse stressors before isoflurane exposure to test whether isoflurane toxicity could be diminished by preconditioning. RESULTS: The ND2360114 mutation had a greater effect on isoflurane- than sevoflurane-mediated changes in gene expression. Isoflurane and sevoflurane did not affect expression of heat shock protein (Hsp) genes (Hsp22, Hsp27, and Hsp68) in wild-type flies, but isoflurane substantially increased expression of these genes in ND2360114 mutant flies. Furthermore, isoflurane and sevoflurane induced expression of oxidative (GstD1 and GstD2) and xenobiotic (Cyp6a8 and Cyp6a14) stress genes to a similar extent in wild-type flies, but the effect of isoflurane was largely reduced in ND2360114 flies. In addition, activating stress response pathways by pre-exposure to anesthetics, heat shock, hyperoxia, hypoxia, or oxidative stress did not suppress isoflurane-induced toxicity in ND2360114 mutant flies. CONCLUSIONS: Mutation of a mitochondrial electron transport chain complex I subunit generates differential effects of isoflurane and sevoflurane on gene expression that may underlie their differential effects on neurotoxicity. Additionally, the mutation produces resistance to preconditioning by stresses that protect the brain in other contexts. Therefore, complex I activity modifies molecular and physiologic effects of anesthetics in an anesthetic-specific manner.

Anatomical Substrates of Rapid Eye Movement Sleep Rebound in a Rodent Model of Post-sevoflurane Sleep Disruption.

BACKGROUND: Previous research suggests that sevoflurane anesthesia may prevent the brain from accessing rapid eye movement (REM) sleep. If true, then patterns of neural activity observed in REM-on and REM-off neuronal populations during recovery from sevoflurane should resemble those seen after REM sleep deprivation. In this study, the authors hypothesized that, relative to controls, animals exposed to sevoflurane present with a distinct expression pattern of c-Fos, a marker of neuronal activation, in a cluster of nuclei classically associated with REM sleep, and that such expression in sevoflurane-exposed and REM sleep-deprived animals is largely similar. METHODS: Adult rats and Targeted Recombination in Active Populations mice were implanted with electroencephalographic electrodes for sleep-wake recording and randomized to sevoflurane, REM deprivation, or control conditions. Conventional c-Fos immunohistochemistry and genetically tagged c-Fos labeling were used to quantify activated neurons in a group of REM-associated nuclei in the midbrain and basal forebrain. RESULTS: REM sleep duration increased during recovery from sevoflurane anesthesia relative to controls (157.0 ± 24.8 min vs. 124.2 ± 27.8 min; P = 0.003) and temporally correlated with increased c-Fos expression in the sublaterodorsal nucleus, a region active during REM sleep (176.0 ± 36.6 cells vs. 58.8 ± 8.7; P = 0.014), and decreased c-Fos expression in the ventrolateral periaqueductal gray, a region that is inactive during REM sleep (34.8 ± 5.3 cells vs. 136.2 ± 19.6; P = 0.001). Fos changes similar to those seen in sevoflurane-exposed mice were observed in REM-deprived animals relative to controls (sublaterodorsal nucleus: 85.0 ± 15.5 cells vs. 23.0 ± 1.2, P = 0.004; ventrolateral periaqueductal gray: 652.8 ± 71.7 cells vs. 889.3 ± 66.8, P = 0.042). CONCLUSIONS: In rodents recovering from sevoflurane, REM-on and REM-off neuronal activity maps closely resemble those of REM sleep-deprived animals. These findings provide new evidence in support of the idea that sevoflurane does not substitute for endogenous REM sleep.

Activity of the Sodium Leak Channel Maintains the Excitability of Paraventricular Thalamus Glutamatergic Neurons to Resist Anesthetic Effects of Sevoflurane in Mice.

BACKGROUND: Stimulation of the paraventricular thalamus has been found to enhance anesthesia recovery; however, the underlying molecular mechanism by which general anesthetics modulate paraventricular thalamus is unclear. This study aimed to test the hypothesis that the sodium leak channel (NALCN) maintains neuronal activity in the paraventricular thalamus to resist anesthetic effects of sevoflurane in mice. METHODS: Chemogenetic and optogenetic manipulations, in vivo multiple-channel recordings, and electroencephalogram recordings were used to investigate the role of paraventricular thalamus neuronal activity in sevoflurane anesthesia. Virus-mediated knockdown and/or overexpression was applied to determine how NALCN influenced excitability of paraventricular thalamus glutamatergic neurons under sevoflurane. Viral tracers and local field potentials were used to explore the downstream pathway. RESULTS: Single neuronal spikes in the paraventricular thalamus were suppressed by sevoflurane anesthesia and recovered during emergence. Optogenetic activation of paraventricular thalamus glutamatergic neurons shortened the emergence period from sevoflurane anesthesia, while chemogenetic inhibition had the opposite effect. Knockdown of the NALCN in the paraventricular thalamus delayed the emergence from sevoflurane anesthesia (recovery time: from 24 ± 14 to 64 ± 19 s, P < 0.001; concentration for recovery of the righting reflex: from 1.13% ± 0.10% to 0.97% ± 0.13%, P < 0.01). As expected, the overexpression of the NALCN in the paraventricular thalamus produced the opposite effects. At the circuit level, knockdown of the NALCN in the paraventricular thalamus decreased the neuronal activity of the nucleus accumbens, as indicated by the local field potential and decreased single neuronal spikes in the nucleus accumbens. Additionally, the effects of NALCN knockdown in the paraventricular thalamus on sevoflurane actions were reversed by optical stimulation of the nucleus accumbens. CONCLUSIONS: Activity of the NALCN maintains the excitability of paraventricular thalamus glutamatergic neurons to resist the anesthetic effects of sevoflurane in mice.

Sevoflurane alleviates inflammation, apoptosis and permeability damage of human umbilical vein endothelial cells induced by lipopolysaccharide by inhibiting endoplasmic reticulum stress via upregulating RORα.

Endothelial dysfunction often accompanies sepsis. Sevoflurane (Sev) is a widely used inhaled anesthetic that has a protective effect on sepsis-associated damage. We aimed to elucidate the role of Sev in endothelial dysfunction by using a model of LPS induced HUVECs. Sev increased the viability and decreased the apoptosis of HUVECs exposed to LPS. Inflammation and endothelial cell adhesion were improved after Sev addition. Besides, Sev alleviated LPS-induced endothelial cell permeability damage in HUVECs. RORα served as a potential protein that bound to Sev. Importantly, Sev upregulated RORα expression and inhibited endoplasmic reticulum (ER) stress in LPS-treated HUVECs. RORα silencing reversed the impacts of Sev on ER stress. Moreover, RORα deficiency or tunicamycin (ER stress inducer) treatment restored the effects of Sev on the viability, apoptosis, inflammation and endothelial permeability damage of HUVECs exposed to LPS. Taken together, Sev ameliorated LPS-induced endothelial cell damage by targeting RORα to inhibit ER stress.

SESN2 attenuates sevoflurane-induced cognitive impairment and neuroinflammation in rats.

Long-term use of sevoflurane, an inhalation anesthetic, could negatively impact cognitive function. Current studies have suggested that cognitive impairment induced by sevoflurane may be associated with neuroinflammation. Sestrin2 (SESN2), which belongs to a family of stress-inducible genes, has been reported to exert neuroprotective effects against brain injury. However, its role and underlying mechanisms in sevoflurane-induced cognitive dysfunction in aged rats remain unknown. A sevoflurane-induced aging rat injury model with or without SESN2 overexpression was constructed. The learning and memory abilities of rats were evaluated by the MWM test. ELISA assay and qRT-PCR were conducted to analyze the level of pro-inflammatory factors in the hippocampus. Levels of oxidative stress markers were measured by DHE staining or kit methods. Neuronal apoptosis in the hippocampus was detected using TUNEL assay. Expression of proteins were analyzed by western blot. Sevoflurane exposure caused elevated protein level of SESN2 in hippocampus and cognitive impairment of aged rats. Importantly, overexpression of SESN2 alleviated sevoflurane-induced cognitive dysfunction and inhibited the production of pro-inflammatory factors, oxidative stress, and neuronal apoptosis in the hippocampus. Furthermore, SESN2 overexpression suppressed NLRP3 inflammasome activation induced by sevoflurane. These findings suggested that SESN2 could exert neuroprotective against sevoflurane-induced nerve injury of aged rats through anti-oxidant and anti-inflammatory effects.

MiR-181a-5p knockdown ameliorates sevoflurane anesthesia-induced neuron injury via regulation of the DDX3X/Wnt/ß-catenin signaling axis.

Sevoflurane is one of the most widely used inhaled anesthetics. MicroRNAs (miRNAs) have been demonstrated to affect sevoflurane anesthesia-induced neuron damage. The purpose of this study was to investigate the role and mechanism of miR-181a-5p in sevoflurane-induced hippocampal neuronal injury. Primary hippocampal neurons were identified using microscopy and immunofluorescence. The viability and apoptosis of sevoflurane anesthesia-induced neurons were detected by cell counting kit-8 (CCK-8) assay and terminal-deoxynucleoitidyl transferase-mediated nick end-labeling (TUNEL) staining assay, respectively. The levels of apoptosis- and oxidative stress-related proteins as well as the markers in the Wnt/ß-catenin signaling pathway were examined by immunoblotting. Enzyme-linked immuno-sorbent assays were performed to examine the levels of inflammatory cytokines. Luciferase reporter assay was conducted to validate the combination between miR-181a-5p and DEAD-box helicase 3, X-linked (DDX3X). Sevoflurane exposure led to significantly inhibited hippocampal neuron viability and elevated miR-181a-5p expression. Knockdown of miR-181a-5p alleviated sevoflurane-induced neuron injury by reducing cell apoptosis, inflammatory response, and oxidative stress. Additionally, DDX3X was targeted and negatively regulated by miR-181a-5p. Moreover, miR-181a-5p inhibitor activated the Wnt/ß-catenin pathway via DDX3X in sevoflurane-treated cells. Rescue experiments revealed that DDX3X knockdown or overexpression of Wnt antagonist Dickkopf-1 (DKK1) reversed the suppressive effects of miR-181a-5p inhibitor on cell apoptosis, inflammatory response, and oxidative stress in sevoflurane-treated neuronal cells. MiR-181a-5p ameliorated sevoflurane-triggered neuron injury by regulating the DDX3X/Wnt/ß-catenin axis, suggesting the potential of miR-181a-5p as a novel and promising therapeutic target for the treatment of sevoflurane-evoked neurotoxicity.