Lasting impact of general anaesthesia on the brain: mechanisms and relevance

Dual effects of GABA A R agonist anesthetics in neurodevelopment and vulnerable brains: From neurotoxic to therapeutic effects

Debates regarding the specific effects of general anesthesia on developing brains have persisted for over 30 years. A consensus has been reached that prolonged, repeated, high-dose exposure to anesthetics is associated with a higher incidence of deficits in behavior and executive function, while single exposure has a relatively minor effect on long-term neurological function. In this review, we summarize the dose-dependent neuroprotective or neurotoxic effects of gamma-aminobutyric acid type A receptor agonists, a representative group of sedatives, on developing brains or central nervous system diseases. Most preclinical research indicates that anesthetics have neurotoxic effects on the developing brain through various signal pathways. However, recent studies on low-dose anesthetics suggest that they may promote neurodevelopment during this critical period. These findings are incomprehensible for the general "dose-effect" principles of pharmacological research, which has attracted researchers' interest and led to the following questions: What is the threshold for the dual effects exerted by anesthetics such as propofol and sevoflurane on the developing brain? To what extent can their protective effects be maximized? What are the underlying mechanisms involved in these effects? Consequently, this issue has essentially become a "mathematical problem." After summarizing the dose-dependent effects of gamma-aminobutyric acid type A receptor agonist sedatives in both the developing brain and the brains of patients with central nervous system diseases, we believe that all such anesthetics exhibit specific threshold effects unique to each drug. These effects range from neuroprotection to neurotoxicity, depending on different brain functional states. However, the exact values of the specific thresholds for different drugs in various brain states, as well as the underlying mechanisms explaining why these thresholds exist, remain unclear. Further in-depth exploration of these issues could significantly enhance the therapeutic translational value of these anesthetics.

Are we missing a trick by not exploiting fruit flies in inflammation-led drug discovery for neurodegeneration?

INTRODUCTION

Alzheimer's disease (AD) remains a formidable challenge in neurodegeneration research, with limited therapeutic options despite decades of study. While Drosophila melanogaster has been instrumental in in modeling AD related Tau and amyloid beta toxicity, inflammation, a key driver of AD pathology, remains unexplored in fly models. Given the evolutionary conservation of innate immune pathways between flies and mammals, drosophila presents a powerful yet underutilized tool for inflammation led drug discovery in AD.

AREAS COVERED

This perspective highlights the relevance of Drosophila in studying neuroinflammatory processes, including microglial-like glial activation, systemic inflammation and gut-brain axis interactions. It further explores how fly models can be leveraged to screen anti-inflammatory compounds and dissect immune related genetic factors implicated in AD.

EXPERT OPINION

By integrating immune modulation in Drosophila-based drug discovery pipeline we can accelerate the identification of novel therapeutic strategies. Fully exploiting the potential of Drosophila in inflammation led drug screening may usher in a new era of AD therapeutics, bridging gaps between fundamental research and translational medicine.

Neurodevelopment at 10 months and 2-3 years old after early and prolonged anaesthesia in infancy: General Anaesthesia & Brain Activity study (GABA) secondary analysis

Background

Effects of early and prolonged exposure to general anaesthesia on the developing brain are unclear. The study objective was to examine developmental outcomes at 10 months and 2-3 yr of age after general anaesthesia planned for >2 h in the first 2 months of life.

Methods

This is a secondary analysis of the General Anaesthesia & Brain Activity (GABA) study-a prospective, single-centre, longitudinal observational study. The final dataset included 59 children who were unexposed and 31 children who were exposed to early prolonged general anaesthesia who completed the primary outcome measure, Bayley Scales of Infant and Toddler Development-III (BSID) assessments at 10 months, at 2-3 yr old, or both. Analyses used adjusted Welch's t-tests, linear regression, and linear mixed effects models.

Results

BSID composite scores for cognition were similar between general anaesthesia and unexposed cohorts at 10 months (P adj=0.566, standardised mean difference [SMD]=0.27) and at 2-3 yr (P adj=0.651, SMD=0.25). Motor and language scores were similar between cohorts at 10 months (motor: P adj=1, SMD=0.13; language: P adj=0.806, SMD=0.19) and fell within typical reference ranges. Linear regression analysis found no association between BSID cognition scores and cumulative hours of general anaesthesia at 10 months (R=0.06, P=0.635) or at 2-3 yr (R=-0.13, P=0.293).

Conclusions

Children with early prolonged general anaesthesia showed BSID scores comparable to age-matched controls. This analysis provides additional preliminary support for the safety of general anaesthesia on the developing brain even when general anaesthesia is prolonged, repeated, or administered very early in life.

S100B in postoperative cognitive impairment: systematic review and meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is prevalent after cardiac and non-cardiac surgeries. It has been generally accepted that POCD is caused by an inflammatory response. This study aimed to determine whether mini-mental state examination (MMSE) scores and the serum levels of two prominent inflammatory factors, S-100B protein (S-100B) and neuron-specific enolase (NSE), can predict POCD among patients undergoing non-cardiac surgeries.

METHOD

A comprehensive literature search was conducted using electronic databases such as PubMed, Web of Science, Scopus, Google Scholar, and Embase up to 14, January 2025 to identify eligible observational studies evaluating the relationship between the incidence of POCD and the serum levels of S100B, NSE, and MMSE score before surgery and 24 h and 7 days after surgery among patients undergoing non-cardiac surgeries.

RESULTS

Our findings demonstrated that patients who developed POCD had higher S100B levels 24 h after surgery compared to before surgery. Compared to pre-operative levels, there were no significant differences in S100B levels at 7 days, NSE levels at 24 h or 7 days, and MMSE scores at 24 h or 7 days after surgery. Age-based analysis revealed that patients with POCD aged ≥60 had higher S100B levels at 24 h post-operative. Among different surgery types, S100B and NSE levels increased significantly 24 h after spinal surgery, while MMSE scores significantly decreased after spinal surgery.

CONCLUSION

S100B may help the early detection of POCD, and the prognostic value of S100B can be evaluated in future studies. Unlike S100B, NSE and MMSE did not show significant differences between POCD and non-POCD groups.

Integrative analysis of circRNA networks in postoperative cognitive dysfunction

OBJECTIVE

In the quest to decipher the molecular intricacies of Postoperative Cognitive Dysfunction (POCD), this study focused on circular RNA (circRNA) and their regulatory networks.

MATERIALS AND METHODS

Analyzing the Gene Expression Omnibus Series (GSE) 147277 dataset, we pinpointed 10 differentially expressed circRNAs linked to POCD.

RESULTS

The ensuing competing endogenous RNA (ceRNA) network, featuring pivotal players like Homo sapiens(hsa)_circ_0003424 and hsa-miR-193b-5p, provided a comprehensive understanding of the molecular players at play in POCD.

CONCLUSION

Additionally, the Protein-Protein Interaction (PPI) network spotlighted 10 core Hub genes, including phosphatase and tensin homolog (PTEN) and signal transducer and activator of transcription 3(STAT3), shedding light on potential therapeutic targets.

Neonatal Diazepam Exposure Decreases Dendritic Arborization and Spine Density of Cortical Pyramidal Neurons in Rats

OBJECTIVE

Benzodiazepines are extensively utilized in pediatric anesthesia and critical care for their anxiolytic and sedative properties. However, preclinical studies indicate that neonatal exposure to GABAergic drugs, including benzodiazepines, leads to long-term cognitive deficits, potentially mediated by altered GABAergic signaling during brain development. This preclinical study investigated the impact of early-life diazepam exposure on cortical neuronal morphology, specifically exploring dendritic arborization and spine density, crucial factors in synaptogenesis.

METHODS

Male and female Sprague Dawley rat pups were exposed to a single neonatal dose of diazepam (30 mg/kg) or vehicle on postnatal day (PND) 7. Golgi-Cox staining was used to assess cortical pyramidal neuron development at 4 developmental stages: neonatal (PND8), infantile (PND15), juvenile (PND30), and adolescence (PND42). Animals were randomized equally to 4 groups: male-vehicle, male-diazepam, female-vehicle, and female-diazepam. Neuronal morphology was evaluated after reconstruction in neurolucida, and dendritic spine density was analyzed through high-power photomicrographs using ImageJ.

RESULTS

Diazepam exposure resulted in decreased dendritic complexity in both sexes, with reduced arborization and spine density observed in cortical pyramidal neurons. Significant differences were found at each developmental stage, indicating a persistent impact. Dendritic length increased with age but was attenuated by diazepam exposure. Branching length analysis revealed decreased complexity after diazepam treatment. Spine density at PND42 was significantly reduced in both apical and basal dendrites after diazepam exposure.

CONCLUSIONS

Neonatal diazepam exposure adversely affected cortical pyramidal neuron development, leading to persistent alterations in dendritic arborization and spine density. These structural changes suggest potential risks associated with early-life diazepam exposure. Further research is needed to unravel the functional consequences of these anatomic alterations.

DNMT3a Deficiency Contributes to Anesthesia/Surgery-Induced Synaptic Dysfunction and Cognitive Impairment in Aged Mice

Perioperative neurocognitive disorder (PND) is a severe postoperative complication in older patients. Epigenetic changes are hallmarks of senescence and are closely associated with cognitive impairment. However, the effects of anesthesia and surgery on the aging brain's epigenetic regulatory mechanisms and its impact on cognitive impairment remain unclear. Using a laparotomy PND model, we report significant reduction in DNA methyltransferase 3a (DNMT3a) in hippocampal neurons of aged mice, which causes global DNA methylation decrease. Knockdown of DNMT3a leads to synaptic disorder and memory impairment in aged mice. Mechanistically, bisulfite sequencing revealed that DNMT3a deficiency reduces methylation in the LRG1 promoter region and promotes its transcription. We also show that activation of TGF-β signaling by the increase in LRG1 level, ultimately impacts the synaptic function. In contrast, both overexpressing DNMT3a or knockdown LRG1 in hippocampus can attenuate the synaptic disorders and rescue postoperative cognitive deficits in aged mice. Our results reveal that DNMT3a is a previously undefined mediator in the pathogenesis of PND, which couples epigenetic regulations with anesthesia/surgery-induced synaptic dysfunction and represents a therapeutic target to tackle PND.

Study on the mechanism of Dexmedetomidine's effect on postoperative cognitive dysfunction in elderly people

Postoperative cognitive dysfunction (POCD) is a common complication among elderly patients following surgical procedures, significantly impairing postoperative recovery and quality of life. The selection and dosage of intraoperative anaesthetic drugs are frequently implicated as contributing factors in the development of POCD. In recent years, dexmedetomidine (DEX), a novel α2-adrenoceptor agonist, has been increasingly utilized in surgical anaesthesia for elderly patients, showing potential as both a preventive and therapeutic agent for POCD. This paper provides a comprehensive review of current research on the mechanisms by which DEX affects POCD in the elderly. Additionally, it explores DEX's mechanisms of action in the context of neuroprotection, anti-inflammation, antioxidative stress, and the regulation of apoptosis, autophagy, and analgesia. The objective is to provide reliable theoretical support and a reference point for the clinical application of DEX in POCD among the elderly, thereby promoting its broader use in clinical practice to improve outcomes and enhance quality of life.

Effects of Xenon on the Developing Brain: Current Insights from Pre-clinical and Clinical Studies

Research has indicated that general anesthetics may potentially induce neuroapoptosis, resulting in long-term neurological deficits in the developing brain. Fortunately, xenon, a noble gas, emerges as a promising candidate for an ideal anesthetic due to its favorable properties, offering neuroprotection and mitigating the neurotoxic effects of other general anesthetics during early life stages. Nevertheless, it is important to highlight that xenon has also been observed to cause neuroapoptosis in the neonatal brain, suggesting that xenon possesses both neuroprotective qualities (as evidenced by pre-clinical and clinical studies) and neurotoxic potential (based mainly on pre-clinical evidence) during brain development. To gain a comprehensive understanding the effects xenon, this review will explore the anesthetic properties of xenon, examine its effects on anesthesia, and elucidate its mechanisms of potential neuroprotection and neurotoxicity in the developing brain. The primary emphasis will be on xenon's application in the context of anesthetic-induced developmental neurotoxicity (AIDN), hypoxic-ischemic encephalopathy (HIE), and teratogenicity, aiming to provide valuable insights for pediatricians, pediatric anesthesiologists, and other healthcare professionals involved in the use and study of xenon anesthesia.

Anesthetic Sevoflurane Induces Enlargement of Dendritic Spine Heads in Mouse Neurons via Tau-Dependent Mechanisms

BACKGROUND

Sevoflurane induces neuronal dysfunction and cognitive impairment. However, the underlying mechanism remains largely to be determined. Tau, cyclophilin D, and dendritic spine contribute to cognitive function. But whether changes in dendritic spines are involved in the effects of sevoflurane and the potential association with tau and cyclophilin D is not clear.

METHODS

We harvested hippocampal neurons from wild-type mice, tau knockout mice, and cyclophilin D knockout mice. We treated these neurons with sevoflurane at day in vitro 7 and measured the diameter of dendritic spine head and the number of dendritic spines. Moreover, we determined the effects of sevoflurane on the expression of excitatory amino acid transporter 3 (EAAT3), extracellular glutamate levels, and miniature excitatory postsynaptic currents (mEPSCs). Finally, we used lithium, cyclosporine A, and overexpression of EAAT3 in the interaction studies.

RESULTS

Sevoflurane-induced tau phosphgorylation increased the diameter of dendritic spine head and decreased the number of dendritic spines in neurons harvested from wild-type and cyclophilin D knockout mice, but not tau knockout mice. Sevoflurane decreased the expression of EAAT3, increased extracellular glutamate levels, and decreased the frequency of mEPSCs in the neurons. Overexpression of EAAT3 mitigated the effects of sevoflurane on dendritic spines. Lithium, but not cyclosporine A, attenuated the effects of sevoflurane on dendritic spines. Lithium also inhibited the effects of sevoflurane on EAAT3 expression and mEPSCs.

CONCLUSIONS

These data suggest that sevoflurane induces a tau phosphorylation-dependent demtrimental effect on dendritic spine via decreasing EAAT3 expression and increasing extracellular glutamate levels, leading to neuronal dysfunction.

Surgical Stress and Non-Surgery Related Stress Synergistically Trigger Meningeal CD8+ T Cells Accumulation and Subsequent Brain Dysfunction in Mice

Patients are usually highly stressed during the immediate perioperative period. It remains unclear whether increased stress contributes to postoperative brain dysfunction. Here, the clinical perioperative setting was mimicked via exploratory laparotomy and perioperative restraint stress. The stress response was assessed by measuring the levels of stress hormones and IL-6 in peripheral blood. Behaviors were evaluated with the open field, novel object recognition, and Barnes maze tests. We found that surgical stress and non-surgery-related stress synergistically trigger meningeal CD8+T cell accumulation, brain dysfunction, and increased stress hormone and IL-6 levels in the peripheral blood of adult mice, but simple surgical stress or non-surgery-related stress had no significant effect on these parameters. Limiting meningeal CD8+ T cell accumulation with an anti-CD8 antibody alleviated the impact of surgery plus perioperative stress on brain function, neuroinflammation, and neurogenesis. The partial elimination of microglia before surgery alleviated postoperative meningeal CD8+ T cell accumulation, cognitive dysfunction, and decreased hippocampal chemotactic factor levels. Our findings indicate that the synergistic effect of surgical stress and non-surgery-related stress contributes to postoperative brain dysfunction by triggering meningeal CD8+ T cell accumulation, suggesting the potential of limiting non-surgery-related stress as a preventive method for postoperative brain dysfunction.

Structural basis for the inhibition of cystathionine-β-synthase by isoflurane and its role in anaesthesia-induced social dysfunction in mice

BACKGROUND

Anaesthesia has been shown to impair social functioning, but the underlying mechanisms remain largely unknown. The volatile anaesthetic isoflurane potentially disrupts the methionine cycle and trans-sulphuration pathway, contributing to social deficits. Cystathionine-β-synthase (CBS), a key enzyme in this pathway, might be targeted by isoflurane. We investigated the CBS-isoflurane interaction and its role in neuronal function and social behaviour.

METHODS

Mice aged 3-15 months were anaesthetised with 2 vol% isoflurane for 2 h, and social behaviours were tested 24 h after exposure. Alterations in neuronal activity were assessed using electrophysiological analysis in vivo. Pharmacological activators (S-adenosylmethionine [SAM]) or inhibitors (amino-oxyacetic acid [AOAA]), and adeno-associated virus (AAV) were used to modulate CBS activity. The binding site of isoflurane on CBS was determined using X-ray crystallography. A novel transgenic model with a point mutation knock-in was constructed to eliminate the CBS-isoflurane interaction.

RESULTS

Isoflurane inhibited CBS activity (by 0.35-fold [0.07] vs 1.00-fold [0.05]; P<0.001), leading to neuronal hypoactivity in the anterior cingulate cortex (ACC) and social impairments in adult and elderly mice. SAM, AOAA, and AAV interventions demonstrated a causal link. Structural and functional analysis identified the lysine 273 (K273) in CBS to be involved in isoflurane inhibition. CBS K273A knock-in mice exhibited increased CBS activity compared with wild-type littermates after isoflurane exposure (2.2-fold [0.22] vs 1.0-fold [0.28]; P<0.001), with successful alleviation of ACC neuronal hypoactivity and social dysfunction.

CONCLUSIONS

These findings reveal a crucial role for CBS inhibition by isoflurane in anaesthesia-induced social impairment.

Sedation and Pain Management in Neonates Undergoing Therapeutic Hypothermia for Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a common cause of significant neonatal morbidity and mortality. The stronghold of the treatment for moderate-to-severe HIE is therapeutic hypothermia (TH) which provides a neuroprotective effect. However, it also is associated with pain and stress. Moreover, neonates with HIE are subjected to a significant number of painful procedures. Untreated pain during the early neonatal period may entail future challenges such as impaired brain growth and development as well as impaired pain sensitivity later in life. Hereby, the provision of adequate sedation and alleviation of pain and discomfort is essential. There are currently no universally accepted guidelines for sedation and pain management for this patient population. In this review, we highlight non-pharmacologic and pharmacologic methods currently in use to provide comfort and sedation to patients with HIE undergoing TH.

Environmental enrichment attenuates sevoflurane anesthesia-induced learning deficits in aged mice through regulating TTBK1 and phosphorylated Tau expression

Perioperative neurocognitive disorders (PND) are a prevalent complication in elderly patients undergoing surgery with general anesthesia. Sevoflurane, a commonly used anesthetic, has been associated with cognitive impairment and neurotoxicity. In this study, we aim to explore the mechanisms through which sevoflurane impairs cognitive function in aged mice and hence identify potential therapeutic strategies. Female C57BL/6 J mice were treated with 2-h-daily Environmental enrichment (EE) for 4 weeks before being exposed to single 3% sevoflurane plus 60% oxygen inhalation for 2 h. WHI-P180, a TTBK1 inhibitor, was administered 5 min prior to anesthesia. Cognitive function, TTBK1, Tau p-Ser422, AT8 (Tau p-Ser202/p-Thr205), TNF-ɑ, IL-6, and IL-1β were measured. The results indicated that sevoflurane inhalation induced cognitive dysfunction, elevated TTBK1 expression and phosphorylated Tau levels, and increased inflammatory factors in the hippocampus of aged mice. However, EE treatment reduced elevated TTBK1, phosphorylated Tau, and inflammatory factor levels in the hippocampus. Additionally, EE alleviated cognitive impairment caused by sevoflurane in aged mice. Furthermore, WHI-P180 mitigated cognitive dysfunction by decreasing Tau phosphorylation and inflammatory cytokine levels in the hippocampus of aged mice. In conclusion, TTBK1 plays a crucial role in cognitive impairment induced by sevoflurane in aged mice, and EE mitigates sevoflurane-induced cognitive dysfunction by inhibiting TTBK1 and Tau protein phosphorylation in the hippocampus of old mice. These findings suggest that EE could be a potential therapeutic strategy for preventing or treating PND in elderly patients undergoing general surgery with sevoflurane anesthesia.

Effect of nerve block combined with superficial general anaesthesia on anaesthetic dosage and anaesthetic awakening in paediatric surgery

BACKGROUND

To compare the effects of nerve block composite general anesthesia and general anesthesia on the dosage of anesthetics and anesthesia awakening in pediatric orthopedic injury patients under anesthesia depth monitoring.

METHODS

Forty pediatric patients with external humerus condylar fractures were randomly distributed into general anesthesia (GA) and nerve block combined with general anesthesia (GNA) groups. Patients in the GA group had induction of anesthesia with propofol at 2.5 mg/kg and remifentanil at 0.6 ug/kg. The Angel-6000D EEG anesthesia depth multi-parameter monitor maintained the EEG awareness index (IOC1) between 40 and 60 and the injury sensitivity index (IOC2) between 30 and 50.

RESULTS

Both intraoperative propofol maintenance in the GA group (6.74 ± 0.93) and propofol maintenance in the GNA group (5.16 ± 0.76) were significantly different upon comparison between the groups (p < 0.05). Intraoperative remifentanil maintenance differed significantly (p < 0.05) between the GA group (0.26 ± 0.04) and the GNA group (0.10 ± 0.04). Comparison of awakening time: the time of eyelid opening, time of completion order, extubation time, and time of recovery of positioning function in the GNA group were markedly shorter than that of the GA group (p < 0.01) with a high level of significance.

CONCLUSION

Nerve block composite general anesthesia under multi-parameter monitoring of depth of anesthesia by Angel-6000D electroencephalogram can lead to a significant reduction in the dosage of propofol and remifentanil, advancement of awakening and extubation time and an increase in the safety of anesthesia in pediatric surgery patients.

Safety profiles of sevoflurane in pediatric patients: a real-world pharmacovigilance assessment based on the FAERS database

Objective

This study aimed to evaluate the safety profile of sevoflurane in pediatric populations using real-world data.

Methods

Data were extracted from the Food and Drug Administration Adverse Event Reporting System (FAERS) from the first quarter of 2004 to the third quarter of 2024. We analyzed reports where sevoflurane was the primary suspect in individuals aged 0-18, employing disproportionality analysis to detect adverse events associated with sevoflurane. We also compared the adverse events related to sevoflurane between pediatric and adult populations.

Results

The FAERS database yielded 21,838,627 adverse event reports for children, with 474 involving sevoflurane as the primary suspect. Descriptive analysis revealed a majority of reports from male patients, primarily reported by physicians. Disproportionality analysis identified significant System Organ Classes (SOC) signals associated with sevoflurane, meeting four detection criteria, including "Cardiac disorders," "Respiratory, thoracic, and mediastinal disorders," and "Vascular disorders." The study also identified previously unreported adverse events, such as "Encephalopathy" and "Hypercapnia." Notable differences in signals were observed between children and adults for "Pulmonary alveolar hemorrhage," "Anaphylactic shock," and "Hypotension."

Conclusion

Our analysis of the FAERS database identified several significant adverse events associated with sevoflurane in pediatrics, affecting the cardiovascular, respiratory, and nervous systems. Differences in adverse event signals between children and adults were also observed. Furthermore, the new adverse events (such as encephalopathy and hypercapnia) indicated that anesthesiologists should be more vigilant in administering sevoflurane.

Neurodevelopmental Outcomes after Multiple General Anesthetic Exposures before 5 Years of Age: A Cohort Study

BACKGROUND

The general anaesthesia or awake-regional anaesthesia in infancy (GAS) trial demonstrated evidence that most neurodevelopmental outcomes at 2 and 5 yr of age in infants who received a single general anesthetic for elective inguinal herniorrhaphy were clinically equivalent when compared to infants who did not receive general anesthesia. More than 20% of the children in the trial had at least one subsequent anesthetic exposure after their initial surgery. Using the GAS database, this study aimed to address whether multiple (two or more) general anesthetic exposures compared to one or no general anesthetic exposure in early childhood were associated with worse neurodevelopmental outcomes at 5 yr.

METHODS

Children with multiple general anesthetic exposures and children with one or no general anesthetic exposure were identified from the GAS database. The primary outcome was the full-scale intelligence quotient on the Wechsler Preschool and Primary Scale of Intelligence (third edition) at 5 yr of age. Secondary outcomes included neurocognitive tests addressing all major developmental domains and caregiver-reported questionnaires assessing emotional and behavioral problems.

RESULTS

Complete assessment was available from a total of 90 children in the multiple general anesthetic group and 141 children in the no or one general anesthetic group. Compared with children with a single or no general anesthetic exposure, multiply exposed children scored on average almost 6 points lower (mean, -5.8; 95% CI, -10.2 to -1.4; P = 0.011) in the Wechsler Preschool and Primary Scale of Intelligence full-scale intelligence quotient. They also demonstrated lower verbal and performance IQ scores and more emotional, behavioral, and executive function difficulties. However, significant residual confounding cannot be excluded from the results due to the observational nature of this study.

CONCLUSIONS

Multiple general anesthetic exposures before 5 yr of age were associated with reduced performance in general intelligence score and some domains of neurodevelopmental assessments. The clinical significance of this study's results must be cautiously interpreted in light of several sources of limitations including small sample size and unadjusted residual confounding. This study illustrates the limitations of trial data sets that may not be fit for the purpose for the secondary analysis.

Rosiglitazone Promotes Oligodendrocyte Development and Myelin Formation of Repeated Neonatal Sevoflurane Exposure via PPARγ Signaling

Sevoflurane is one of the most commonly used general anesthetics for children and infants. Recent research indicates that repeated exposure to sevoflurane in neonates induces cognitive and fine motor deficits. Peroxisome proliferator-activated receptor-γ (PPARγ) agonists have garnered significant attention as potential therapies for a variety of neurological conditions. In this research, we evaluated whether pretreatment with rosiglitazone in neonatal mice could address myelination defects, cognitive impairment, and fine motor dysfunction via PPARγ. The mice were exposed to 3% sevoflurane for 2 h on postnatal days 6-8 (P6-P8). Behavioral tests were conducted from P29 to P34. Additionally, we evaluated morphological and functional changes related to myelin. Our results showed that rosiglitazone pretreatment significantly ameliorated the cognitive and fine motor impairments of repeated neonatal sevoflurane exposure. In addition, rosiglitazone pretreatment promoted oligodendrocyte precursor cells (OPCs) differentiation and myelination. This suggests that rosiglitazone may be used in clinical settings to enhance the security of neonatal sevoflurane exposure. Furthermore, PPARγ and fatty acid synthase (FASN) may be mediators for rosiglitazone, which alleviates myelination defects, cognitive impairment, and fine motor dysfunction.

Maternal exposure to general anesthesia and labor epidural analgesia during pregnancy and delivery, and subsequent neurodevelopmental outcomes in children

Gestation is a vulnerable developmental period, and exposures during that time may have longterm implications. While evaluating the implications of early exposures on children is an important public health concern, as opposed to other chemical exposures, medications are given for a clinical purpose, and any potential injury must be weighed against the benefits of these medications to the mother and child. This review examines neurodevelopmental outcomes in children following two maternal anesthetic exposures: general anesthesia and labor epidural analgesia. Exposure to general anesthetic agents has been found to interfere with neurodevelopment in animal models, and exposures in children, including prenatal exposures are also associated with worse neurodevelopmental outcomes. While these medications are likely to impact neurodevelopment in animals, it remains unclear if prenatal general anesthetic exposure causes the reported differences in children. As a result, since avoidance or delay of necessary surgery in mothers may result in adverse outcomes in mothers and children, necessary surgery in pregnant mothers should proceed without delay. Concerns about the safety of maternal neuraxial labor analgesia ("epidurals") have also emerged due to a reported association with autism spectrum diagnoses in their children. This may be due to familial factors in pregnant women electing for neuraxial labor analgesia rather than the "epidural" itself. In addition, since clinically significant differences in neurodevelopmental scores in children following exposure have not been found, and a mechanism of injury has not yet been identified in preclinical studies, the benefits of neuraxial labor analgesia appear to outweigh the potential risks.

A Scoping Review of the Mechanisms Underlying Developmental Anesthetic Neurotoxicity

Although anesthesia makes painful or uncomfortable diagnostic and interventional health care procedures tolerable, it may also disrupt key cellular processes in neurons and glia, harm the developing brain, and thereby impair cognition and behavior in children. Many years of studies using in vitro, animal behavioral, retrospective database studies in humans, and several prospective clinical trials in humans have been invaluable in discerning the potential toxicity of anesthetics. The objective of this scoping review was to synthetize the evidence from preclinical studies for various mechanisms of toxicity across diverse experimental designs and relate their findings to those of recent clinical trials in real-world settings.

Nicotinamide adenine dinucleotide supplementation fails to enhance anesthetic recovery in rodents

Nicotinamide Adenine Dinucleotide (NAD+) is implicated in bioenergetics, DNA repair, and senescence. Depletion of NAD+ is associated with aging and neurodegenerative disease, prompting a growing interest in NAD+ supplementation. With rising over-the-counter use of NAD, understanding their impact on anesthetic recovery becomes essential. This study investigates the effect of NADH, a common NAD+ precursor, on anesthesia in rodents. Baseline and post-anesthesia (1.5% isoflurane) open field and Y-maze activity were recorded in adult male and female C57BL/6 mice (n = 8-10/group). NADH (150 mg/kg, intraperitoneal) or vehicle (0.9% normal saline) were given at baseline or during anesthesia. The NADH-treated group exhibited a significant decrease in open-field activity relative to vehicle-treated. This diminished activity was reflected in reduced distance travelled and average velocity after emergence from anesthesia in the NADH-treated group. NADH treatment did not improve Y-maze performance after anesthesia, partly related to reduced locomotor activity in the NADH-treated group. This study demonstrates that NADH does not appear to hasten recovery from anesthesia. Instead, there was a depression in open-field activity and no change in Y-maze performance with NADH supplementation, indicators of locomotive and cognitive recovery in rodents. The broad implications of NAD+ in aging are likely to shape supplementation trends, highlighting the importance of understanding the potential influence of administering NAD+ on anesthetic sensitivity and recovery.

Low-Intensity Transcranial Ultrasound Stimulation Promotes Recovery in Blood Flow and Movement Following Prolonged Anesthesia

General anesthesia is a routine operation before surgical and diagnostic procedures. However, delayed emergence from anesthesia can lead to various complications. Researchers have sought to use transcranial ultrasound stimulation to promote motor and cognitive function recovery after short-period anesthesia (<60 min). However, whether the significant decline of neurovascular activities induced by prolonged anesthesia (>90 min) would affect ultrasound-induced recovery remains unclear. In this study, we investigated the effects of ultrasound stimulation on the recovery of mice after prolonged anesthesia by analyzing the changes of cortical blood flow and movement. C57BL/6 mice (n =24) were randomly assigned to the three groups: Control, Sham, and Ultrasound Stimulation. We utilized laser speckle contrast imaging to record cortical blood flow during and after 120 min anesthesia. Additionally, we recorded the emergence time of the first and full movements as indicators of recovery. The results showed that ultrasound stimulation significantly accelerated the recovery of blood flow (F(2,21) =3.83, p =0.038, $\eta _{p}^{{2}} =0.267$ ) and reduced the emergence time of the first movement (F(2,21) =2.70, p =0.091, $\eta _{p}^{{2}} =0.205$ ) after 120 min anesthesia. Furthermore, we observed a medium negative correlation between the blood flow after 120 min anesthesia and the emergence time of the first movement (r(22) $= -0.487$ , p =0.016, 95% CI: [-0.744,-0.104]). These findings revealed the potential of ultrasound stimulation to facilitate recovery after prolonged anesthesia.

The potential mechanism of mitochondrial homeostasis in postoperative neurocognitive disorders: an in-depth review

Postoperative neurocognitive disorders (PND) are the most common neurological disorders following surgery and anaesthesia before and within 12 months after surgery, with a high prevalence in the geriatric population. PND can severely deteriorate the quality of life of patients, especially among the elderly, mainly manifested as memory loss, attention, decline and language comprehension disorders, mostly in elderly patients, with an incidence as high as 31%. Previous studies have also raised the possibility of accelerated cognitive decline and underlying neuropathological processes associated with diseases that affect cognitive performance (e.g. Alzheimer's dementia) for reasons related to anaesthesia and surgery. Currently, most research on PND has focused on various molecular pathways, especially in the geriatric population. The various hypotheses that have been proposed regarding the mechanisms imply peripheral neuroinflammation, oxidative stress, mitochondrial homeostasis, synaptic function, autophagy disorder, blood-brain barrier dysfunction, the microbiota-gut-brain axis and lack of neurotrophic support. However, the underlying pathogenesis and molecular mechanisms of PND have not yet been uncovered. Recent research has focused on mitochondrial homeostasis. In this paper, we present a review of various studies to better understand and characterize the mechanisms of associated cognitive dysfunction. As the biochemical basis of PND becomes more clearly defined, future treatments based on mitochondrial homeostasis modulation can prove to be very promising.

Brain health: A concern for anaesthesiologists and intensivists

Damage to the brain can have disastrous and long-lasting consequences. The European Society of Anaesthesiology and Intensive Care (ESAIC) is aware of the importance of taking good care of the brain, both of patients and of anaesthesia and intensive care unit (ICU) caregivers, and has organised a complete learning track on brain health to bring this concern to the attention of practitioners. This learning track included an online Focus Meeting on Brain Health (November 25, 2023). We here provide readers with a digest of the information that was delivered during that meeting in an opinion paper driven by the authors' own reading of the literature. It is divided according to the meeting's sessions, including how to improve the health of an injured brain, how to keep a young or old brain healthy, how to keep a healthy adult brain unimpaired, how monitoring can impact brain health in the operating room and in the intensive care unit, and how to keep the anaesthesia and ICU caregivers' brain healthy. Each part is a brief and focused summary. The main delivered messages are that the management of injured brain patients involves an adequate choice of sedation, adequate brain monitoring, and focused attention to specific points depending on the underlying pathology; that several measures can be undertaken to protect the brain of the very young needing anaesthesia; that it is possible to detect older patients at risk of postoperative neurocognitive disorders, and that dedicated perioperative management by a multidisciplinary expert team may improve their outcomes; that apparently healthy adult brains may suffer during anaesthesia; that the electroencephalogram may track peri-operative brain dysfunction, and that female patients should be given special care in this respect; that multimodal brain monitoring helps to detect pathological processes and to maintain brain homeostasis; and that burnout in anaesthesiologists can be effectively fought using personal, organisational, managerial and legal approaches.

Effect of Anesthesia During Pregnancy, Delivery, and Childhood on Autism Spectrum Disorder: A Systematic Review and Meta-analysis

To investigate the association between exposure to anesthesia during three periods of pregnancy, delivery, and childhood and autism spectrum disorder (ASD). PubMed, Scopus, Web of Science, Embase, Google Scholar, PsycArticles, and PsycINFO were searched from the date of database inception to 1 December 2022. Studies reported the association between exposure to anesthesia during pregnancy, delivery, and childhood and ASD were included. Extracted variables included hazard ratio (HR), relative risk or odds ratio, standard error, and 95% confidence interval (CI). Effect estimates were pooled using random-effects meta-analysis. In total, 16 studies including 8,156,608 individuals were included in the meta-analysis. Labor epidural anesthesia during delivery was associated with ASD in the general population (adjusted HR = 1.16, 95% CI, 1.06-1.28) but not in the sibling population (adjusted HR = 1.06, 95% CI, 0.98-1.15). Other anesthesia during delivery was not associated with ASD (general population: adjusted HR = 1.08, 95% CI, 0.99-1.17; sibling population: adjusted HR = 1.20, 95% CI, 0.81-1.79). Three studies suggested that exposure to anesthesia during pregnancy was associated with ASD in offspring (adjusted HR = 2.15, 95% CI, 1.32-3.48). There was no significant association between exposure to general anesthesia during childhood and ASD (adjusted HR = 1.02, 95% CI, 0.60-1.72). This meta-analysis did not confirm the association between exposure to anesthesia during labour and ASD. Previous observational studies used the neurotoxicity of anesthesia to biologically explain significant associations, but in fact different controls for confounding factors led to differences in associations. The evidence for pregnancy and childhood was limited given the small number of studies in these periods.

Alterations in hippocampal somatostatin interneurons, GABAergic metabolism, and ASL perfusion in an aged male mouse model of POCD aggravated by sleep fragmentation

Sleep fragmentation (SF) is increasingly recognized as a contributing factor to postoperative cognitive dysfunction (POCD). Given the critical roles of somatostatin (SST) interneurons, associated gamma-aminobutyric acid (GABA)ergic neurotransmitters, and hippocampal perfusion in sleep-related cognition, this study examined changes in these mechanisms in preoperative SF affecting POCD induced by anesthesia/surgery in aged male mice. The Morris water maze (MWM), novel object recognition (NOR), and Y maze tests were utilized to evaluate POCD. Arterial spin labeling (ASL) was employed to measure hippocampal regional cerebral blood flow (rCBF). In vitro assays quantified the levels of GABAergic metabolites-such as SST, neuropeptide Y (NPY), glutamic acid decarboxylase 1 (GAD1), vesicular GABA transporter (VGAT), and GABA and the distribution of SST interneurons in the hippocampus through enzyme-linked immunosorbent assay and immunofluorescence. Preoperative 24-h SF exacerbated anesthesia/surgery-induced spatial memory impairments observed in the MWM, NOR, and Y maze tests. Preoperative 24-h SF significantly increased the number of SST interneurons in hippocampal CA1, elevated hippocampal levels of SST, NPY, GAD1, and GABA, and reduced the rCBF. Preoperative SF aggravated POCD in aged male mice, with an increased number of SST interneurons in hippocampal CA1, elevated hippocampal GABAergic metabolites, and a further reduction in rCBF.

Age-dependent cerebral vasodilation induced by volatile anesthetics is mediated by NG2+ vascular mural cells

Anesthesia can influence cerebral blood flow by altering vessel diameter. Using in vivo two-photon imaging, we examined the effects of volatile anesthetics, sevoflurane and isoflurane, on vessel diameter in young and adult mice. Our results show that these anesthetics induce robust dilation of cortical arterioles and arteriole-proximate capillaries in adult mice, with milder effects in juveniles and no dilation in infants. This anesthesia-induced vasodilation correlates with decreased cytosolic Ca2+ levels in NG2+ vascular mural cells. Optogenetic manipulation of these cells bidirectionally regulates vessel diameter, and their ablation abolishes the vasodilatory response to anesthetics. In immature brains, NG2+ mural cells are fewer in number and express lower levels of Kir6.1, a subunit of ATP-sensitive potassium channels. This likely contributes to the age-dependent differences in vasodilation, as Kir6.1 activation promotes, while its inhibition reduces, anesthesia-induced vasodilation. These findings highlight the essential role of NG2+ mural cells in mediating anesthesia-induced cerebral vasodilation.

Unraveling the role and mechanism of mitochondria in postoperative cognitive dysfunction: a narrative review

Postoperative cognitive dysfunction (POCD) is a frequent neurological complication encountered during the perioperative period with unclear mechanisms and no effective treatments. Recent research into the pathogenesis of POCD has primarily focused on neuroinflammation, oxidative stress, changes in neural synaptic plasticity and neurotransmitter imbalances. Given the high-energy metabolism of neurons and their critical dependency on mitochondria, mitochondrial dysfunction directly affects neuronal function. Additionally, as the primary organelles generating reactive oxygen species, mitochondria are closely linked to the pathological processes of neuroinflammation. Surgery and anesthesia can induce mitochondrial dysfunction, increase mitochondrial oxidative stress, and disrupt mitochondrial quality-control mechanisms via various pathways, hence serving as key initiators of the POCD pathological process. We conducted a review on the role and potential mechanisms of mitochondria in postoperative cognitive dysfunction by consulting relevant literature from the PubMed and EMBASE databases spanning the past 25 years. Our findings indicate that surgery and anesthesia can inhibit mitochondrial respiration, thereby reducing ATP production, decreasing mitochondrial membrane potential, promoting mitochondrial fission, inducing mitochondrial calcium buffering abnormalities and iron accumulation, inhibiting mitophagy, and increasing mitochondrial oxidative stress. Mitochondrial dysfunction and damage can ultimately lead to impaired neuronal function, abnormal synaptic transmission, impaired synthesis and release of neurotransmitters, and even neuronal death, resulting in cognitive dysfunction. Targeted mitochondrial therapies have shown positive outcomes, holding promise as a novel treatment for POCD.

Overexpression of Nfs1 Cysteine Desulphurase Relieves Sevoflurane-Induced Neurotoxicity and Cognitive Dysfunction in Neonatal Mice Via Suppressing Oxidative Stress and Ferroptosis

Clinical evidence suggests that multiple exposures to sevoflurane in young people may be detrimental to cognitive development. Iron accumulation in the hippocampus is associated with sevoflurane-induced neurotoxicity and cognitive deficits. The cysteine desulphurase, Nfs1, the rate-limiting enzyme for the biosynthesis of iron-sulphur clusters, plays a role in cellular iron homeostasis. However, the impact of Nfs1-mediated ferroptosis on sevoflurane-induced neurotoxicity and cognitive impairments in neonatal mice remains undetermined. Neonatal mice at postnatal Day 6 received 3% sevoflurane daily for 3 consecutive days. Cognitive function was assessed using the Morris water maze test, and neurotoxicity was evaluated through terminal deoxynucleotidyl transferase dUTP nick end labeling and immunofluorescence staining. Here, HT22 hippocampal neurons were employed for in-vitro experiments, and Fe2+ accumulation was measured. Ferroptosis-related genes, including glutathione peroxidase 4 (GPX4), transferrin receptor 1 (TFR1) and ferritin, in the hippocampus and HT22 cells were observed, along with oxidative stress-related indicators such as reactive oxygen species (ROS), methionine adenosyltransferase (MAT), glutathione (GSH) and lipid peroxidation (LPO). Transmission electron microscopy was utilized to examine the mitochondrial microstructure. Sevoflurane exposure significantly decreased Nfs1 expression in the hippocampus of mice and HT22 cells. This exposure resulted in cognitive impairments and neuronal damage in the hippocampus, which were alleviated by overexpression of Nfs1. Intracellular and mitochondrial iron accumulation occurred in HT22 cells following sevoflurane treatment. Sevoflurane exposure also significantly reduced GSH levels and increased levels of malondialdehyde, ROS and LPO in the hippocampus or HT22 cells. Additionally, sevoflurane exposure decreased GPX4 expression but increased TFR1 and ferritin expression in the hippocampus or HT22 cells. Overexpression of Nfs1 reversed the sevoflurane-induced alterations in ferroptosis-related genes and oxidative stress-related indicators. Furthermore, overexpression of Nfs1 alleviated sevoflurane-induced mitochondrial dysfunction. However, Nfs1 knockdown alone did not result in cognitive impairments, ferroptosis or oxidative stress. The overexpression of Nfs1 mitigated sevoflurane-induced neurotoxicity and cognitive impairment by modulating oxidative stress and ferroptosis through the regulation of iron metabolism and transport.

Comparison of spinal anesthesia and local anesthesia in percutaneous interlaminar endoscopic lumbar discectomy for L5/S1 disc herniation: a retrospective cohort study

BACKGROUND

Interlaminar endoscopic lumbar discectomy (IELD) is a prevalent method for managing lumbar disc herniation. Local anesthesia (LA) is frequently employed during IELD, albeit with its merits and drawbacks. The spinal anesthesia (SA) represents a feasible anesthetic strategy for IELD; however, the availability of clinical research data is currently limited.

METHODS

The propensity score matching was conducted to ensure the comparability of the SA and LA groups. The outcome measures were operation time, intraoperative visual analogue scale (VAS) for pain, need for adjuvant analgesia, intraoperative vital signs, blood loss, adverse surgical events, anesthesia-related complications, postoperative bed rest duration, VAS for pain at 2 h postoperatively, Oswestry Disability Index score (ODI), satisfaction with surgical efficacy, and willingness to undergo reoperation at 6 months postoperatively.

RESULTS

Fifty-six patients were assigned to each group. Significant differences were found between the groups regarding intraoperative VAS for pain, use of adjuvant analgesics, willingness to undergo reoperation, maximum intraoperative systolic blood pressure, and variability (P < 0.05). Compared to the LA group, the SA group had lower VAS for pain at 2 h postoperatively, a longer operation time, a longer duration of postoperative bedrest, and more anesthesia-related complications (P < 0.05). No significant intergroup differences were detected in intraoperative heart rate variability, blood loss, ODI, satisfaction with surgical efficacy, and surgery-related complications (P > 0.05).

CONCLUSION

SA as an alternative anesthesia for IELD surgery holds great promise, exhibiting superior efficacy compared to LA. However, it is crucial to meticulously evaluate the indications due to potential risks associated with this form of anesthesia.

Progesterone alleviates esketamine-induced hypomyelination via PI3K/Akt signaling pathway in the developing rat brain

The neurodevelopmental toxicity of anesthetics has been confirmed repeatedly, and esketamine is now widely used in pediatric surgeries. Oligodendrocyte precursor cells (OPCs) evolved into mature oligodendrocytes (OLs) and formed myeline sheath during the early brain development. In this study, we investigated whether esketamine exposure interrupted development of OPCs and induced hypomyelination in rats. Further we explored the roles of PI3K/Akt phosphorylation in OPCs development and myelination. Sprague Dawley rats with different ages (postnatal day (P) 1, 3, 7 and 12) were exposed to 40mg/kg esketamine. Progesterone treatment was given (16 mg/kg per day for 3 days) 24 h after esketamine exposure via the intraperitoneal route. Corpus callosum tissues were collected at P8 or P14 for western blot and immunofluorescence analyses. Esketamine exposure at P7 and P12 significantly reduced myelin basic protein (MBP) expression and CC1+ OLs number in corpus callosum. Esketamine exposure at P7 not only aggravated the mature OLs apoptosis, also decreased the OPCs proliferation and differentiation, which was related with dephosphorylation of PI3K/Akt. Progesterone was able to promote OPCs differentiation and ameliorate esketamine-induced hypomyelination by enhancing PI3K/Akt phosphorylation. Stage-dependent abnormality of OPCs/OLs after esketamine leads to the esketamine-induced hypomyelination. Esketamine interrupted OPCs evolution via PI3K/Akt signaling pathway, which can be ameliorated by progesterone.

Anesthetic neurotoxicity in the developing brain: an update on theinsights and implications for fetal surgery

This review describes an in-depth analysis of the neurotoxicity associated with the anesthetic agents used during fetal surgery, intending to highlight the importance of understanding the effects of general anesthetics on the developing brain, particularly in the context of open fetal surgery, where high doses are applied to facilitate surgical access and augment uterine relaxation. We examined evidence from preclinical studies in rodents and primates, along with studies in human subjects, with the results collectively suggesting that general anesthetics can disrupt brain development and lead to long-lasting neurological deficits. Our review underscores the clinical implications of these findings, indicating an association between extensive anesthetic exposure in early life and subsequent cognitive deficits. The current standard of anesthetic care for fetal surgical procedures was scrutinized, and recommendations have been proposed to mitigate the risk of anesthetic neurotoxicity. These recommendations emphasize the need for careful selection of anesthetic techniques to minimize fetal exposure to potentially harmful agents. In conclusion, while the benefits of fetal surgery in addressing immediate risks often outweigh the potential neurotoxic effects of anesthesia, the long-term developmental impacts nevertheless warrant consideration. Our analysis suggests that the use of general anesthetics in fetal surgery, especially at high doses, poses a significant risk of developmental neurotoxicity. As such, it is imperative to explore safer alternatives, such as employing different methods of uterine relaxation and minimizing the use of general anesthetics, to achieve the necessary surgical conditions. Further research, particularly in clinical settings, is essential to fully understand the risks and benefits of anesthetic techniques in fetal surgery.

Regulating the activity of GABAergic neurons in the ventral pallidum alters the general anesthesia effect of propofol

The full mechanism of action of propofol, a commonly administered intravenous anesthetic drug in clinical practice, remains elusive. The focus of this study was the role of GABAergic neurons which are the main neuron group in the ventral pallidum (VP) closely associated with anesthetic effects in propofol anesthesia. The activity of VP GABAergic neurons following propofol anesthesia in Vgat-Cre mice was observed via detecting c-Fos immunoreactivity by immunofluorescence and western blotting. Subsequently, chemogenetic techniques were employed in Vgat-Cre mice to regulate the activity of VP GABAergic neurons. The role of VP GABAergic neurons in generating the effects of general anesthesia induced by intravenous propofol was further explored through behavioral tests of the righting reflex. The results revealed that c-Fos expression in VP GABAergic neurons in Vgat-Cre mice dramatically decreased after propofol injection. Further studies demonstrated that chemogenetic activation of VP GABAergic neurons during propofol anesthesia shortened the duration of anesthesia and promoted wakefulness. Conversely, the inhibition of VP GABAergic neurons extended the duration of anesthesia and facilitated the effects of anesthesia. The results obtained in this study suggested that regulating the activity of GABAergic neurons in the ventral pallidum altered the effect of propofol on general anesthesia.

Gut Microbiota-Metabolite-Brain Axis Reconstitution Reverses Sevoflurane-Induced Social and Synaptic Deficits in Neonatal Mice

Background: The mechanisms underlying social dysfunction caused by repeated sevoflurane in early life remain unclear. Whether the gut microbiota-metabolite-brain axis is involved in the mechanism of sevoflurane developmental neurotoxicity still lacks report. Methods: Mice received 3% sevoflurane at postnatal day (PND) 6, 7, and 8 for 2 h per day. Metagenomic sequencing and untargeted metabolomic analysis were applied to investigate the effects of sevoflurane on gut microbiota and metabolism. The animal social behavior and the synaptic development were analyzed during PND 35. Subsequently, fecal microbiota transplantation (FMT) from the control group and bile acid administration were performed to see the expected rescuing effect on socially related behaviors that were impaired by repeated sevoflurane exposure in the mice. Results: In the 3-chamber test, sevoflurane-exposed mice spent less time with stranger mice compared with the control group. The density of both the apical and basal spine decreased in mice exposed to sevoflurane. In addition, repeated sevoflurane exposure led to a notable alteration in the gut microbiota and metabolite synthesis, particularly bile acid. FMT reduced the production of intestinal bile acid and attenuated the effect of sevoflurane exposure on social function and synaptic development. Cholestyramine treatment mimics the protective effects of FMT. Conclusions: The gut microbiota-metabolite-brain axis underlies social dysfunction caused by sevoflurane exposure in early age, and bile acid regulation may be a promising intervention to this impairment.

Exposure to Operative Anesthesia in Childhood and Subsequent Neurobehavioral Diagnoses: A Natural Experiment Using Appendectomy

BACKGROUND

Observational studies of anesthetic neurotoxicity may be biased because children requiring anesthesia commonly have medical conditions associated with neurobehavioral problems. This study takes advantage of a natural experiment associated with appendicitis to determine whether anesthesia and surgery in childhood were specifically associated with subsequent neurobehavioral outcomes.

METHODS

This study identified 134,388 healthy children with appendectomy and examined the incidence of subsequent externalizing or behavioral disorders (conduct, impulse control, oppositional defiant, attention-deficit hyperactivity disorder) or internalizing or mood or anxiety disorders (depression, anxiety, or bipolar disorder) when compared to 671,940 matched healthy controls as identified in Medicaid data between 2001 and 2018. For comparison, this study also examined 154,887 otherwise healthy children admitted to the hospital for pneumonia, cellulitis, and gastroenteritis, of which only 8% received anesthesia, and compared them to 774,435 matched healthy controls. In addition, this study examined the difference-in-differences between matched appendectomy patients and their controls and matched medical admission patients and their controls.

RESULTS

Compared to controls, children with appendectomy were more likely to have subsequent behavioral disorders (hazard ratio, 1.04; 95% CI, 1.01 to 1.06; P = 0.0010) and mood or anxiety disorders (hazard ratio, 1.15; 95% CI, 1.13 to 1.17; P < 0.0001). Relative to controls, children with medical admissions were also more likely to have subsequent behavioral (hazard ratio, 1.20; 95% CI, 1.18 to 1.22; P < 0.0001) and mood or anxiety (hazard ratio, 1.25; 95% CI, 1.23 to 1.27; P < 0.0001) disorders. Comparing the difference between matched appendectomy patients and their matched controls to the difference between matched medical patients and their matched controls, medical patients had more subsequent neurobehavioral problems than appendectomy patients.

CONCLUSIONS

Although there is an association between neurobehavioral diagnoses and appendectomy, this association is not specific to anesthesia exposure and is stronger in medical admissions. Medical admissions, generally without anesthesia exposure, displayed significantly higher rates of these disorders than appendectomy-exposed patients.

EDITOR’S PERSPECTIVE

Propofol total intravenous anesthesia vs. sevoflurane inhalation anesthesia: Effects on post‑operative cognitive dysfunction and inflammation in geriatric patients undergoing laparoscopic surgery

Propofol total intravenous anesthesia (TIVA) or sevoflurane inhalation anesthesia (IA) affects post-operative cognitive dysfunction in geriatric patients undergoing laparoscopic surgery; however, relevant real-world clinical evidence on the matter is limited. The present study aimed to compare the effects of propofol TIVA and sevoflurane IA on post-operative cognitive dysfunction in the aforementioned type of patients. The present prospective study enrolled 197 geriatric patients undergoing laparoscopic surgery. Patients were assigned to the propofol TIVA group (n=97) and sevoflurane IA group (n=100) according to the actual anesthesia regimens. The mini-mental state examination (MMSE) score was assessed before surgery and on day (D)1, D3 and D7 following surgery in both groups. The MMSE score on D1 was higher in the TIVA group compared with the IA group (P=0.006). The change in the MMSE scores from before surgery to D1 (P<0.001), D3 (P=0.011) and D7 (P=0.003) was smaller in the TIVA group vs. the IA group. Multivariate linear regression analyses suggested that the anesthesia method of TIVA (vs. IA) was independently related to the increased MMSE score on D1 (b=0.803; P=0.001) and D7 (b=0.472; P=0.025). The levels of interleukin (IL)-17A, IL-6 and tumor necrosis factor-α on D1, D3 and D7 exhibited a slightly decreasing trend in the TIVA group vs. the IA group, although the difference was not statistically significant (all P>0.05). Notably, the levels of IL-17A before surgery (P=0.015), on D3 (P=0.016) and D7 (P=0.002), as well as those of IL-6 on D1 (P=0.027), were negatively associated with the MMSE score at the corresponding time points. Overall, the present study demonstrates that propofol TIVA ameliorates post-operative cognitive dysfunction on D1 compared with sevoflurane IA and exerts a potentially suppressive effect on inflammation in geriatric patients undergoing laparoscopic surgery.

Feasibility and effectiveness of transcutaneous auricular vagus nerve stimulation (taVNS) in awake mice

AIMS

Transcutaneous auricular vagus nerve stimulation (taVNS) is widely used to treat a variety of disorders because it is noninvasive, safe, and well tolerated by awake patients. However, long-term and repetitive taVNS is difficult to achieve in awake mice. Therefore, developing a new taVNS method that fully mimics the method used in clinical settings and is well-tolerated by awake mice is greatly important for generalizing research findings related to the effects of taVNS. The study aimed to develop a new taVNS device for use in awake mice and to test its reliability and effectiveness.

METHODS

We demonstrated the reliability of this taVNS device through retrograde neurotropic pseudorabies virus (PRV) tracing and evaluated its effectiveness through morphological analysis. After 3 weeks of taVNS application, the open field test (OFT) and elevated plus maze (EPM) were used to evaluate anxiety-like behaviors, and the Y-maze test and novel object recognition test (NORT) were used to evaluate recognition memory behaviors, respectively.

RESULTS

We found that repetitive taVNS was well tolerated by awake mice, had no effect on anxiety-like behaviors, and significantly improved memory.

CONCLUSION

Our findings suggest that this new taVNS device for repetitive stimulation of awake mice is safe, tolerable, and effective.

Dihydromyricetin protects sevoflurane-induced mitochondrial dysfunction in HT22 hippocampal cells

Sevoflurane (Sev) is a commonly used inhalation anaesthetic that has been shown to cause hippocampus dysfunction through multiple underlying molecular processes, including mitochondrial malfunction, oxidative stress and inflammation. Dihydromyricetin (DHM) is a 2,3-dihydroflavonoid with various biological properties, such as anti-inflammation and anti-oxidative stress. The purpose of this study was to investigate the effect of DHM on Sev-induced neuronal dysfunction. HT22 cells were incubated with 10, 20 and 30 μM of DHM for 24 h, and then stimulated with 4% Sev for 6 h. The effects and mechanism of DHM on inflammation, oxidative stress and mitochondrial dysfunction were explored in Sev-induced HT22 cells by Cell Counting Kit-8, flow cytometry, enzyme-linked immunosorbent assay, reverse transcription-quantitative polymerase chain reaction, colorimetric detections, detection of the level of reactive oxygen species (ROS), mitochondrial ROS and mitochondrial membrane potential (MMP), immunofluorescence and western blotting. Our results showed that DHM increased Sev-induced cell viability of HT22 cells. Pretreatment with DHM attenuated apoptosis, inflammation, oxidative stress and mitochondrial dysfunction in Sev-elicited HT22 cells by remedying the abnormality of the indicators involved in these progresses, including apoptosis rate, the cleaved-caspase 3 expression, as well as the level of tumour necrosis factor α, interleukin (IL)-1β, IL-6, malondialdehyde, superoxide dismutase, catalase, ROS, mitochondrial ROS and MMP. Mechanically, pretreatment with DHM restored the Sev-induced the expression of SIRT1/FOXO3a pathway in HT22 cells. Blocking of SIRT1 counteracted the mitigatory effect of DHM on apoptosis, inflammation, oxidative stress and mitochondrial dysfunction in Sev-elicited HT22 cells. Collectively, pretreatment with DHM improved inflammation, oxidative stress and mitochondrial dysfunction via SIRT1/FOXO3a pathway in Sev-induced HT22 cells.

ADAR1 prevents ZBP1-dependent PANoptosis via A-to-I RNA editing in developmental sevoflurane neurotoxicity

It is well established that sevoflurane exposure leads to widespread neuronal cell death in the developing brain. Adenosine deaminase acting on RNA-1 (ADAR1) dependent adenosine-to-inosine (A-to-I) RNA editing is dynamically regulated throughout brain development. The current investigation is designed to interrogate the contributed role of ADAR1 in developmental sevoflurane neurotoxicity. Herein, we provide evidence to show that developmental sevoflurane priming triggers neuronal pyroptosis, apoptosis and necroptosis (PANoptosis), and elicits the release of inflammatory factors including IL-1β, IL-18, TNF-α and IFN-γ. Additionally, ADAR1-P150, but not ADAR1-P110, depresses cellular PANoptosis and inflammatory response by competing with Z-DNA/RNA binding protein 1 (ZBP1) for binding to Z-RNA in the presence of sevoflurane. Further investigation demonstrates that ADAR1-dependent A-to-I RNA editing mitigates developmental sevoflurane-induced neuronal PANoptosis. To restore RNA editing, we utilize adeno-associated virus (AAV) to deliver engineered circular ADAR-recruiting guide RNAs (cadRNAs) into cells, which is capable of recruiting endogenous adenosine deaminases to promote cellular A-to-I RNA editing. As anticipated, AAV-cadRNAs diminishes sevoflurane-induced cellular Z-RNA production and PANoptosis, which could be abolished by ADAR1-P150 shRNA transfection. Moreover, AAV-cadRNAs delivery ameliorates developmental sevoflurane-induced spatial and emotional cognitive deficits without influence on locomotor activity. Taken together, these results illustrate that ADAR1-P150 exhibits a prominent role in preventing ZBP1-dependent PANoptosis through A-to-I RNA editing in developmental sevoflurane neurotoxicity. Application of engineered cadRNAs to rectify the compromised ADAR1-dependent A-to-I RNA editing provides an inspiring direction for possible clinical preventions and therapeutics.

The Effects of Sevoflurane and Aβ Interaction on CA1 Dendritic Spine Dynamics and MEGF10-Related Astrocytic Synapse Engulfment

General anesthetics may accelerate the neuropathological changes related to Alzheimer's disease (AD), of which amyloid beta (Aβ)-induced toxicity is one of the main causes. However, the interaction of general anesthetics with different Aβ-isoforms remains unclear. In this study, we investigated the effects of sevoflurane (0.4 and 1.2 maximal alveolar concentration (MAC)) on four Aβ species-induced changes on dendritic spine density (DSD) in hippocampal brain slices of Thy1-eGFP mice and multiple epidermal growth factor-like domains 10 (MEGF10)-related astrocyte-mediated synaptic engulfment in hippocampal brain slices of C57BL/6 mice. We found that both sevoflurane and Aβ downregulated CA1-dendritic spines. Moreover, compared with either sevoflurane or Aβ alone, pre-treatment with Aβ isoforms followed by sevoflurane application in general further enhanced spine loss. This enhancement was related to MEGF10-related astrocyte-dependent synaptic engulfment, only in AβpE3 + 1.2 MAC sevoflurane and 3NTyrAβ + 1.2 MAC sevoflurane condition. In addition, removal of sevoflurane alleviated spine loss in Aβ + sevoflurane. In summary, these results suggest that both synapses and astrocytes are sensitive targets for sevoflurane; in the presence of 3NTyrAβ, 1.2 MAC sevoflurane alleviated astrocyte-mediated synaptic engulfment and exerted a lasting effect on dendritic spine remodeling.

Potential Risk of Choline Alfoscerate on Isoflurane-Induced Toxicity in Primary Human Astrocytes

OBJECTIVE

Isoflurane, a widely used common inhalational anesthetic agent, can induce brain toxicity. The challenge lies in protecting neurologically compromised patients from neurotoxic anesthetics. Choline alfoscerate (L-α-Glycerophosphorylcholine, α-GPC) is recognized for its neuroprotective properties against oxidative stress and inflammation, but its optimal therapeutic window and indications are still under investigation. This study explores the impact of α-GPC on human astrocytes, the most abundant cells in the brain that protect against oxidative stress, under isoflurane exposure.

METHODS

This study was designed to examine changes in factors related to isoflurane-induced toxicity following α-GPC administration. Primary human astrocytes were pretreated with varying doses of α-GPC (ranging from 0.1 to 10.0 μM) for 24 hours prior to 2.5% isoflurane exposure. In vitro analysis of cell morphology, water-soluble tetrazolium salt-1 assay, quantitative real-time polymerase chain reaction, proteome profiler array, and transcriptome sequencing were conducted.

RESULTS

A significant morphological damage to human astrocytes was observed in the group that had been pretreated with 10.0 mM of α-GPC and exposed to 2.5% isoflurane. A decrease in cell viability was identified in the group pretreated with 10.0 μM of α-GPC and exposed to 2.5% isoflurane compared to the group exposed only to 2.5% isoflurane. Quantitative real-time polymerase chain reaction revealed that mRNA expression of heme-oxygenase 1 and hypoxia-inducible factor-1α, which were reduced by isoflurane, was further suppressed by 10.0 μM α-GPC pretreatment. The proteome profiler array demonstrated that α-GPC pretreatment influenced a variety of factors associated with apoptosis induced by oxidative stress. Additionally, transcriptome sequencing identified pathways significantly related to changes in isoflurane-induced toxicity caused by α-GPC pretreatment.

CONCLUSION

The findings suggest that α-GPC pretreatment could potentially enhance the vulnerability of primary human astrocytes to isoflurane-induced toxicity by diminishing the expression of antioxidant factors, potentially leading to amplified cell damage.

Perioperative impact of ultrasound-guided ilioinguinal and iliohypogastric nerve blocks in patients undergoing pelvic fracture surgery

Pelvic fractures present a severe and complex clinical challenge. This study aimed to compare ultrasound-guided ilioinguinal (IIN) and iliohypogastric nerve (IHN) blocks with conventional general anesthesia (GA) in patients undergoing internal fixation surgery for pelvic fractures. A retrospective analysis was conducted on 100 patients equally divided into ultrasound-guided and control groups. The study monitored hemodynamics, intraoperative anesthesia drug usage, postoperative pain levels, and the incidence of adverse reactions between the 2 groups. The ultrasound-guided group underwent ultrasound-guided IHN and IIN blocks combined with GA. The ultrasound-guided group exhibited significant advantages for hemodynamic measurements at specific time points, lower consumption of Propofol and Remifentanil, and reduced pain intensity across all evaluated time intervals (P < .05). The incidence rate of adverse reactions was significantly lower in the ultrasound group (P = .016). Ultrasound-guided anesthesia is a superior alternative to conventional GA for managing pelvic fractures through internal fixation surgery. It offers advantages in terms of hemodynamic stability, drug consumption, postoperative pain management, and adverse reaction reduction.

Nicotinamide Adenine Dinucleotide Does Not Improve Anesthetic Recovery in Rodents

Nicotinamide Adenine Dinucleotide (NAD+) is implicated in bioenergetics, DNA repair, and senescence. Depletion of NAD+ is associated with aging and neurodegenerative disease, prompting a growing interest in NAD+ supplementation. With rising over-the-counter use of NAD, understanding their impact on perioperative recovery becomes essential. This study investigates the effect of NADH, a common NAD+ precursor, on anesthesia in rodents. Baseline and post-anesthesia (1.5% isoflurane) open field and Y-maze activity were recorded in adult male and female C57/BL6 mice (n = 8-10/group). NADH (150 mg/kg, intraperitoneal) or vehicle (0.9% normal saline) were given at baseline or during anesthesia. The NADH-treated group exhibited a significant decrease in open-field activity relative to vehicle-treated. This diminished activity was reflected in reduced distance travelled and average velocity after emergence from anesthesia in the NADH-treated group. NADH treatment did not improve Y-maze performance after anesthesia as the number of visits to the novel arm was significantly decreased. This study demonstrates a potentially adverse impact of NADH on recovery from anesthesia. We revealed a depression in open-field activity and Y-maze performance with NADH supplementation, an indicator of cognitive recovery in rodents. The broad implications of NAD+ in aging are likely to shape supplementation trends, highlighting the importance of understanding the potential influence of administering NAD+ on anesthetic sensitivity and recovery.

Early Postnatal Exposure to Midazolam Causes Lasting Histological and Neurobehavioral Deficits via Activation of the mTOR Pathway

Exposure to general anesthetics can adversely affect brain development, but there is little study of sedative agents used in intensive care that act via similar pharmacologic mechanisms. Using quantitative immunohistochemistry and neurobehavioral testing and an established protocol for murine sedation, we tested the hypothesis that lengthy, repetitive exposure to midazolam, a commonly used sedative in pediatric intensive care, interferes with neuronal development and subsequent cognitive function via actions on the mechanistic target of rapamycin (mTOR) pathway. We found that mice in the midazolam sedation group exhibited a chronic, significant increase in the expression of mTOR activity pathway markers in comparison to controls. Furthermore, both neurobehavioral outcomes, deficits in Y-maze and fear-conditioning performance, and neuropathologic effects of midazolam sedation exposure, including disrupted dendritic arborization and synaptogenesis, were ameliorated via treatment with rapamycin, a pharmacologic mTOR pathway inhibitor. We conclude that prolonged, repetitive exposure to midazolam sedation interferes with the development of neural circuitry via a pathologic increase in mTOR pathway signaling during brain development that has lasting consequences for both brain structure and function.

Effect of different anesthetic modalities on postoperative delirium in elderly hip fractures: A meta-analysis

BACKGROUND

Previous findings on the effect of general versus spinal anesthesia on postoperative delirium in elderly people with hip fractures are somewhat controversial. This article included the latest randomized controlled study for meta-analysis to evaluate the effect of general anesthesia (GA) and spinal anesthesia (SA) on delirium after hip fracture surgery in the elderly, so as to guide the clinical.

METHODS

Cochrane Library, PubMed, Web Of Science, and Embase were searched from inception up to January 16, 2024. Randomized controlled trial (RCT) was included to evaluate the postoperative results of GA and SA in elderly patients (≥50 years old) undergoing hip fracture surgery. Two researchers independently screened for inclusion in the study and extracted data. Heterogeneity was assessed by the I²and Chi-square tests, and P < .1 or I² ≥ 50% indicated marked heterogeneity among studies. The Mantel-Haenszel method was used to estimate the combined relative risk ratio (RR) and the corresponding 95% confidence interval (CI) for the binary variables.

RESULTS

Nine randomized controlled trials were included. There was no significant difference (RR = 0.93, 95% CI = 0.774-1.111, P > .05) in the incidence of postoperative delirium between the GA group and the SA group. In intraoperative blood transfusion (RR = 1.0, 95% CI = 0.77-1.28, Z = 0.04, P = .971), pulmonary embolism (RR = 0.795, 95% CI = 0.332-1.904, Z = 0.59, P = .606), pneumonia (RR = 1.47, 95% CI = 0.75-2.87, P = .675), myocardial infarction (RR = 0.97, 95% CI = 0.24-3.86, Z = 0.05, P = .961), heart failure (RR = 0.80, 95% CI = 0.26-2.42, Z = 0.40, P = .961), urinary retention (RR = 1.42, 95% CI = 0.77-2.61, Z = 1.11, P = .267) were similar between the 2 anesthetic techniques.

CONCLUSION

There is no significant difference in the effect of GA and SA on postoperative delirium in elderly patients with hip fracture, and their effects on postoperative complications are similar.

Isoflurane-induced neuroinflammation and NKCC1/KCC2 dysregulation result in long-term cognitive disorder in neonatal mice

BACKGROUND

The inhalational anesthetic isoflurane is commonly utilized in clinical practice, particularly in the field of pediatric anesthesia. Research has demonstrated its capacity to induce neuroinflammation and long-term behavioral disorders; however, the underlying mechanism remains unclear [1]. The cation-chloride cotransporters Na+-K+-2Cl--1 (NKCC1) and K+-2Cl--2 (KCC2) play a pivotal role in regulating neuronal responses to gamma-aminobutyric acid (GABA) [2]. Imbalances in NKCC1/KCC2 can disrupt GABA neurotransmission, potentially leading to neural circuit hyperexcitability and reduced inhibition following neonatal exposure to anesthesia [3]. Therefore, this study postulates that anesthetics have the potential to dysregulate NKCC1 and/or KCC2 during brain development.

METHODS

We administered 1.5% isoflurane anesthesia to neonatal rats for a duration of 4 h at postnatal day 7 (PND7). Anxiety levels were assessed using the open field test at PND28, while cognitive function was evaluated using the Morris water maze test between PND31 and PND34. Protein levels of NKCC1, KCC2, BDNF, and phosphorylated ERK (P-ERK) in the hippocampus were measured through Western blotting analysis. Pro-inflammatory cytokines IL-1β, IL-6, and TNF-α were quantified using ELISA.

RESULTS

We observed a decrease in locomotion trajectories within the central region and a significantly shorter total distance in the ISO group compared to CON pups, indicating that isoflurane induces anxiety-like behavior. In the Morris water maze (MWM) test, rats exposed to isoflurane exhibited prolonged escape latency onto the platform. Additionally, isoflurane administration resulted in reduced time spent crossing in the MWM experiment at PND34, suggesting long-term impairment of memory function. Furthermore, we found that isoflurane triggered activation of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α; downregulated KCC2/BDNF/P-ERK expression; and increased the NKCC1/KCC2 ratio in the hippocampus of PND7 rats. Bumetadine (NKCC1 specific inhibitors) reversed cognitive damage and effective disorder induced by isoflurane in neonatal rats by inhibiting TNF-α activation, normalizing IL-6 and IL-1β levels, restoring KCC2 expression levels as well as BDNF and ERK signaling pathways. Based on these findings, it can be speculated that BDNF, P-ERK, IL-1β, IL-6 and TNF - α may act downstream of the NKCC1/KCC2 pathway.

CONCLUSIONS

Our findings provide evidence that isoflurane administration in neonatal rats leads to persistent cognitive deficits through dysregulation of the Cation-Chloride Cotransporters NKCC1 and KCC2, BDNF, p-ERK proteins, as well as neuroinflammatory processes.

Influence of Surgery Preparation Time on Patient Outcomes

Aims

This study aimed to analyze the effects of the surgery preparation time on patient outcomes.

Background

Postoperative complications have a decisive effect on postoperative survival. The anesthesia time is a crucial determinant of such complications. Competent operating room nurses can shorten the surgery preparation time, which is the time from when anesthesia is first administered to the making of the surgical incision. The shortening of this preparation time can shorten the anesthesia time and may reduce postoperative complications. However, discussion of this preparation time is insufficient. Therefore, this study analyzed the effect of the surgery preparation time on patient outcomes.

Methods

From electronic health records data, this retrospective cohort study used the data of 1,944 patients who had been immediately admitted to the ICU after their surgery between 2017 and 2020. The patients were divided into two groups: ≥30 minutes preparation time and <30 minutes preparation time groups. We performed chi-squared tests and t-tests to determine differences in preoperation, intraoperation, and postoperation characteristics of the patients and patient outcomes based on the surgery preparation time. Furthermore, we performed a multiple logistic regression by including 12 adjusted variables to determine the influence of the surgery preparation time on patient outcomes.

Results

Among the 1,944 patients, 820 were in the ≥30 minutes preparation time group and 1,124 in the <30 minutes preparation time group. The multiple logistic regression analysis showed that the surgery preparation time affects alertness (OR = 1.44; 95% CI: [1.09, 1.90]), ventilator application (OR = 1.32; 95% CI: [1.03, 1.70]), and length of stay in the ICU (OR = 1.69; 95% CI [1.16, 2.47]).

Conclusions

The surgery preparation time affects postoperative patient outcomes. The competence of operating room nurses is the most essential aspect of the surgery preparation time. Implications for Nursing Management. It is important to analyze operating room nurses' tasks, standardize the tasks, and educate nurses according to their experience level to reduce the surgery preparation time and improve patient outcomes.