The effects of general anaesthesia on memory in children: a comparison between propofol and sevoflurane

Propofol-induced hippocampal Neurotoxicity: A mitochondrial perspective

Propofol is a frequently used anesthetic. It can induce neurodegeneration and inhibit neurogenesis in the hippocampus. This effect may be temporary. It can, however, become permanent in vulnerable populations, such as the elderly, who are more susceptible to Alzheimer's disease, and neonates and children, whose brains are still developing and require neurogenesis. Current clinical practice strategies have failed to provide an effective solution to this problem. In addition, the molecular mechanism of this toxicity is not fully understood. Recent advances in molecular research have revealed that apoptosis, in close association with mitochondria, is a crucial mechanism through which propofol contributes to hippocampal toxicity. Preventing the toxicity of propofol on the hippocampus has shown promise in in-vivo, in-vitro, and to a lesser extent human studies. This study seeks to provide a comprehensive literature review of the effects of propofol toxicity on the hippocampus via mitochondria and to suggest translational suggestions based on these molecular results.

Comparison of propofol and desflurane for postoperative neurocognitive function in patients with aneurysmal subarachnoid hemorrhage: A prospective randomized trial

Background

Following aneurysmal subarachnoid hemorrhage, 40-50% of survivors experience cognitive dysfunction, which affects their quality of life. Anesthetic agents play a pivotal role in aneurysm surgeries. However, substantial evidence regarding their effects on neurocognitive function is lacking. This study evaluated the effects of propofol and desflurane on postoperative neurocognitive function and serum S-100B levels.

Methods

One hundred patients were equally randomized to receive either propofol (Group P) or desflurane (Group D). Cognitive function was assessed using the Montreal Cognitive Assessment scale at three different time points: Preoperatively, at the time of discharge, and one month after surgery. Perioperative serum levels of S-100B were also measured.

Results

The preoperative mean cognitive score in Group P was 21.64 + 4.46 and in Group D was 21.66 + 4.07 (P = 0.79). At discharge, a significant decrease in cognitive scores was observed compared to preoperative scores (Group P- 20.91 + 3.94, P = 0.03 and Group D-19.28 + 4.22, P = 0.00); however, scores were comparable between the two groups (P = 0.09). One month following surgery, mean cognitive scores were 22.63 + 3.57 in Group P and 20.74 + 3.89 in Group D, and the difference was significant (P = 0.04). Higher memory and orientation scores were observed in Group P than in Group D at one month (P < 0.05) in the subgroup analysis. Both groups had similar serum S-100B levels.

Conclusion

The mean cognitive scores one month after surgery improved significantly with propofol compared with desflurane, but without clinical significance. Individual domain analysis demonstrated that orientation and memory scores were better preserved with propofol.

Tau protein plays a role in the mechanism of cognitive disorders induced by anesthetic drugs

Cognitive disorders are mental health disorders that can affect cognitive ability. Surgery and anesthesia have been proposed to increase the incidence of cognitive dysfunction, including declines in memory, learning, attention and executive function. Tau protein is a microtubule-associated protein located in the axons of neurons and is important for microtubule assembly and stability; its biological function is mainly regulated by phosphorylation. Phosphorylated tau protein has been associated with cognitive dysfunction mediated by disrupting the stability of the microtubule structure. There is an increasing consensus that anesthetic drugs can cause cognitive impairment. Herein, we reviewed the latest literature and compared the relationship between tau protein and cognitive impairment caused by different anesthetics. Our results substantiated that tau protein phosphorylation is essential in cognitive dysfunction caused by anesthetic drugs, and the possible mechanism can be summarized as "anesthetic drugs-kinase/phosphatase-p-Tau-cognitive impairment".

General anesthesia in children and long-term neurodevelopmental deficits: A systematic review

Background

Millions of children experienced surgery procedures requiring general anesthesia (GA). Any potential neurodevelopmental risks of pediatric anesthesia can be a serious public health issue. Various animal studies have provided evidence that commonly used GA induced a variety of morphofunctional alterations in the developing brain of juvenile animals.

Methods

We conducted a systematic review to provide a brief overview of preclinical studies and summarize the existing clinical studies. Comprehensive literature searches of PubMed, EMBASE, CINAHL, OVID Medline, Web of Science, and the Cochrane Library were conducted using the relevant search terms “general anesthesia,” “neurocognitive outcome,” and “children.” We included studies investigating children who were exposed to single or multiple GA before 18, with long-term neurodevelopment outcomes evaluated after the exposure(s).

Results

Seventy-two clinical studies originating from 18 different countries published from 2000 to 2022 are included in this review, most of which are retrospective studies (n = 58). Two-thirds of studies (n = 48) provide evidence of negative neurocognitive effects after GA exposure in children. Neurodevelopmental outcomes are categorized into six domains: academics/achievement, cognition, development/behavior, diagnosis, brain studies, and others. Most studies focusing on children &lt;7 years detected adverse neurocognitive effects following GA exposure, but not all studies consistently supported the prevailing view that younger children were at greater risk than senior ones. More times and longer duration of exposures to GA, and major surgeries may indicate a higher risk of negative outcomes.

Conclusion

Based on current studies, it is necessary to endeavor to limit the duration and numbers of anesthesia and the dose of anesthetic agents. For future studies, we require cohort studies with rich sources of data and appropriate outcome measures, and carefully designed and adequately powered clinical trials testing plausible interventions in relevant patient populations.

Prolonged sevoflurane exposure causes abnormal synapse development and dysregulates beta-neurexin and neuroligins in the hippocampus in neonatal rats

BACKGROUND

The underlying molecular mechanisms of the excitatory/inhibitory (E/I) imbalance induced by sevoflurane exposure to neonates remain poorly understood. This study aimed to investigate the long-term effects of prolonged sevoflurane exposure to neonatal rats during the peak period of synaptogenesis on the changes of trans-synaptic neurexin-neuroligin interactions, synaptic ultrastructure in the hippocampus and cognition.

METHODS

A total of 30 rat pups at postnatal day (P) 7 was randomly divided into two groups: the control group (exposed to 30 % oxygen balanced with nitrogen) and the sevoflurane group (exposed to 2.5 % sevoflurane plus 30 % oxygen balanced with nitrogen) for 6 h. Neurocognitive behaviors were assessed with the Open field test at P23-25 and the Morris water maze test at P26-30. The expression of β-neurexin (β-NRX), N-methyl-d-aspartate receptor 2 subunit (NR2A and NR2B), neuroligin-1 (NLG-1), neuroligin-2 (NLG-2), postsynaptic density protein-95 (PSD-95), α1-subunit of the γ-aminobutyric acid A receptor (GABAAα1) and gephyrin in the hippocampus at P30 were measured by Western blot. The ultrastructure of synapses was examined under electron microscope.

RESULTS

Prolonged sevoflurane exposure at P7 resulted in cognitive deficiency in adolescence, as well as the downregulation of β-NRX, NR2A, NR2B, NLG-1, and PSD-95, and the upregulation of GABAAα1, NLG-2, and gephyrin in the hippocampal CA3 region. Sevoflurane anesthesia also increased the number of symmetric synapses in the hippocampus.

CONCLUSIONS

Prolonged sevoflurane exposure during the brain development leads to cognitive deficiency and disproportion of excitatory/inhibitory synapses which may be caused by dysregulated expression of synaptic adhesion molecules of β-NRX and neuroligins.

The Safety of Propofol Versus Sevoflurane for General Anesthesia in Children: A Meta-Analysis of Randomized Controlled Trials

Background

Propofol and sevoflurane are the most used anesthetics for pediatric surgery. Emergence agitation, postoperative nausea and vomiting and postoperative pain are the primary adverse effect of these general anesthetics. Many clinical studies had compared the safety of propofol and sevoflurane in pediatric surgery, but the results were controversial.

Objectives

To evaluate the evidence surrounding the safety of propofol versus sevoflurane for general anesthesia in children.

Methods

Databases including PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang Data and Vip Data were searched to collect relevant articles. Trials were strictly selected according to previously defined inclusion and exclusion criteria. RevMan 5.3 software was used for meta-analyses.

Results

Twenty randomized controlled trials recruiting 1,550 children for general anesthesia were included, with overall low-moderate methodological quality. There was evidence that compared with sevoflurane anesthesia, propofol anesthesia significantly decreased the incidence of emergence agitation (OR = 4.99, 95% CI, 3.67–6.80; P &lt; 0.00001), postoperative nausea and vomiting (OR = 1.91, 95% CI, 1.27–2.87; P  =  0.002) and postoperative pain (OR = 1.72, 95% CI, 1.11–2.64; P = 0.01) in children. However, patients who received sevoflurane tended to have shorter times to eye opening (MD = −2.58, 95% CI, −2.97– −2.19; P &lt; 0.00001) and times to extubation (MD = −1.42, 95% CI, −1.81– −1.02; P &lt; 0.00001).

Conclusions

This review reveals that the children who received propofol anesthesia had the lower risks of emergence agitation, postoperative nausea and vomiting and postoperative pain when compared with sevoflurane anesthesia. But the children who received sevoflurane recovered slightly faster than those received propofol. Considering the limitations of the included studies, better methodological quality and large controlled trials are expected to further quantify the safety of propofol and sevoflurane for general anesthesia in children.

Safety of general anaesthetics on the developing brain: are we there yet?

Thirty years ago, neurotoxicity induced by general anaesthetics in the developing brain of rodents was observed. In both laboratory-based and clinical studies, many conflicting results have been published over the years, with initial data confirming both histopathological and neurodevelopmental deleterious effects after exposure to general anaesthetics. In more recent years, animal studies using non-human primates and new human cohorts have identified some specific deleterious effects on neurocognition. A clearer pattern of neurotoxicity seems connected to exposure to repeated general anaesthesia. The biochemistry involved in this neurotoxicity has been explored, showing differential effects of anaesthetic drugs between the developing and developed brains. In this narrative review, we start with a comprehensive description of the initial concerning results that led to recommend that any non-essential surgery should be postponed after the age of 3 yr and that research into this subject should be stepped up. We then focus on the neurophysiology of the developing brain under general anaesthesia, explore the biochemistry of the observed neurotoxicity, before summarising the main scientific and clinical reports investigating this issue. We finally discuss the GAS trial, the importance of its results, and some potential limitations that should not undermine their clinical relevance. We finally suggest some key points that could be shared with parents, and a potential research path to investigate the biochemical effects of general anaesthesia, opening up perspectives to understand the neurocognitive effects of repetitive exposures, especially in at-risk children.

Anesthetic Exposure During Childhood and Neurodevelopmental Outcomes: A Systematic Review and Meta-analysis

IMPORTANCE

Clinical studies of neurodevelopmental outcomes after anesthetic exposure have evaluated a range of outcomes with mixed results.

OBJECTIVE

To examine via meta-analyses the associations between exposure to general anesthesia and domain-specific neurodevelopmental outcomes in children.

DATA SOURCES

PubMed/MEDLINE, Embase, CINAHL, Web of Science and the Cochrane Library were searched from inception to August 31, 2021.

STUDY SELECTION

Inclusion criteria were exposures to procedures requiring general anesthesia at younger than 18 years and evaluation of long-term neurodevelopmental function after exposure. Studies lacking unexposed controls or focused on children with major underlying comorbidities were excluded.

DATA EXTRACTION AND SYNTHESIS

Extracted variables included effect size; hazard, risk, or odds ratio; number of exposures; procedure type; major comorbidities; age of exposure and assessment; presence of unexposed controls; and study design. Studies were independently reviewed by 2 coders, and review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

The main outcomes were standardized mean differences (SMD) for scores in the neurodevelopmental domains of academics, behavioral problems, cognition, executive function, general development, language, motor function, nonverbal reasoning, social cognition, and hazard and risk of neurodevelopmental disorder diagnoses.

RESULTS

A total of 31 studies contributed data for meta-analysis. For each of the assessed neurodevelopmental domains, the numbers of children evaluated ranged from 571 to 63 315 exposed and 802 to 311 610 unexposed. Children with any exposure (single or multiple) had significantly worse behavioral problems scores, indicating more behavioral problems (SMD, -0.10; 95% CI, -0.18 to -0.02; P = .02), and worse scores in academics (SMD, -0.07; 95% CI -0.12 to -0.01; P = .02), cognition (SMD, -0.03; 95% CI, -0.05 to 0.00; P = .03), executive function (SMD, -0.20; 95% CI, -0.32 to -0.09; P < .001), general development (SMD, -0.08; 95% CI, -0.13 to -0.02; P = .01), language (SMD, -0.08; 95% CI, -0.14 to -0.02; P = .01), motor function (SMD, -0.11; 95% CI, -0.21 to -0.02; P = .02), and nonverbal reasoning (SMD, -0.15; 95% CI, -0.27 to -0.02; P = .02). Higher incidences of neurodevelopmental disorder diagnoses were also reported (hazard ratio, 1.19; 95% CI, 1.09 to 1.30; P < .001; risk ratio, 1.81; 95% CI, 1.25 to 2.61; P = .002).

CONCLUSIONS AND RELEVANCE

These findings support the hypothesis that associations between anesthetic exposure during childhood and subsequent neurodevelopmental deficits differ based on neurodevelopmental domain.

Experience and Management of the Adverse Effects of Analgesics After Surgery: A Pediatric Patient Perspective

After surgery, the adverse effects (AEs) of analgesics are common and critical factors influencing the postoperative experience of pediatric patients. Inadequate management of AEs has been found to prolong hospital stay, increase readmission rates and decrease satisfaction with care. The aim of this qualitative descriptive study was to better understand the AEs of analgesics from the perspective of adolescent patients with idiopathic scoliosis after spinal surgery. A total of 7 patients participated in the study. Semistructured interviews were conducted at discharge and 1 week after discharge. Transcribed data were analyzed using qualitative content analysis and themes were identified. Overall, participants most frequently reported gastrointestinal and cognitive AEs, with constipation being the most persistent and bothersome. The pediatric participants used a combination of 3 strategies to mitigate analgesic AEs, namely pharmacologic, nonpharmacologic, and reduction of analgesic intake. Participants demonstrated a lack of understanding of AEs and involvement in their own care. Future studies should be conducted to evaluate the efficacy of nonpharmacological strategies in managing analgesic AEs for pediatric patients after surgery.

Longitudinal assessment of cognitive function in young children undergoing general anaesthesia

BACKGROUND

Exposure to general anaesthesia in children may be related to deficits in certain areas of cognition. It is unclear if these deficits could be measured in the immediate postoperative period in young children. The goal of the current study was to evaluate the trajectory of cognitive function in the domains of processing speed, working memory, and fine motor skills amongst children aged 2.5-6 yr who underwent general anaesthesia for elective surgery.

METHODS

Children who were scheduled to receive general anaesthesia for surgery were recruited for assessment of cognitive function at three times: preoperatively, 1-2 weeks postoperatively, and 3 months postoperatively. Assessments included processing speed, working memory, and fine motor skills. To assess longitudinal changes in the cognitive outcomes, linear mixed models were built with visit number included as a categorical variable and subject-specific random intercepts.

RESULTS

Sixty-one children (33 girls [54%]) enrolled in the study. Twenty-three children (38%) had received general anaesthesia previously. Significant improvements in picture memory, cancellation, and the processing speed composite were found at Visit 2. The improvement in cancellation and processing speed composite remained significant at Visit 3. Statistically significant improvement in Mullen fine motor score was noticed at Visit 3 compared with Visit 1. The pattern of results did not depend upon prior anaesthesia exposure.

CONCLUSIONS

General anaesthesia for elective surgery in young children was not associated with declines in working memory, processing speed, and fine motor skills in the first 3 months postoperatively, including in children with prior exposure to anaesthesia.

Awake Spinal Fusion

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Awake spinal fusion (ASF) integrates advancements in surgical techniques and anesthetic modalities with the aim to maximize benefits and improve outcomes from the surgical and anesthetic standpoints.

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ASF employs minimally invasive or endoscopic surgical techniques that are complemented by regional modalities of anesthesia and analgesia.

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The current evidence, albeit limited, has shown better results with ASF in terms of postoperative pain scores, a patient's need for opioids, postoperative hospital length of stay, and rehabilitation compared with the conventional technique of open spinal fusion with the patient under general anesthesia.

Longitudinal associations between exposure to anesthesia and neurocognitive functioning in pediatric medulloblastoma

AIM

To examine whether anesthesia exposure is associated with neurocognitive decline in pediatric medulloblastoma.

METHODS

Patients were treated at St. Jude Children's Research Hospital and completed ≥2 protocol-directed neurocognitive assessments (n = 107) as part of a multisite clinical trial for pediatric medulloblastoma (NCT00085202). Patients received risk-adapted craniospinal photon irradiation, followed by four cycles of high-dose chemotherapy and stem cell rescue. Neurocognitive testing was completed at study baseline (after surgery and <2 weeks of starting radiation therapy) and annually for 5 years. Data on anesthesia exposure during treatment was abstracted from medical records.

RESULTS

Patients were 10.2 years at diagnosis on average (SD = 4.5; 37% female, 73% average-risk). Mean cumulative anesthesia duration was 20.4 h (SD = 15.2; range 0.7-55.6 h). In the overall group, longer anesthesia duration was associated with greater declines in IQ (Estimate = -0.08, P < 0.001), attention (Estimate = -0.10, P < .001) and processing speed (Estimate = -0.13, P < 0.001). Similar results were shown in subgroups of patients who were <7 years at diagnosis (IQ = -0.14, P = 0.027; Attention = -0.25: P = 0.011), ≥7 years at diagnosis (Attention = -0.07, P = 0.039; Processing Speed = -0.08, P = 0.022), treated for high-risk disease (IQ = -0.09, P = 0.024; Attention = -0.11, P = 0.034; Processing Speed = -0.13, P = 0.001), or treated for average-risk disease (IQ = -0.05, P = .022; Attention = -0.08, P = 0.011; Processing Speed = -0.10, P < 0.001).

CONCLUSION

Greater anesthesia exposure is a risk factor for clinically significant neurocognitive decline, in addition to factors of age at diagnosis and treatment risk arm. This result is notable as there are evidence-based strategies that can limit the need for anesthesia. Limiting anesthesia exposure, as feasible, may mitigate neurocognitive late effects, and thus, improve quality of life for survivors.

Central cholinergic system mediates working memory deficit induced by anesthesia/surgery in adult mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is consistently associated with increased morbidity and mortality, which has become a major concern of patients and caregivers. Although POCD occurs mainly in aged patients, it happens at any age. Previous studies demonstrated that anesthesia/surgery had no effects on reference memory of adult mice. However, whether it impairs working memory remains unclear. Working memory deficit would result in many deficits of executive function. We hypothesized that anesthesia/surgery impaired the working memory of adult mice and the central cholinergic system was involved.

METHOD

Tibial fracture internal fixation under the anesthesia of isoflurane was performed in two-month-old C57BL/6 mice. Two days later, the spatial reference memory and working memory were measured by a Morris Water Maze (MWM). Donepezil, an inhibitor of acetylcholinesterase (AChE), was administered in another cohort mice for 4 weeks. Then, the working memory was measured by MWM 2 days after anesthesia/surgery. Western blot was used to detect the protein levels of acetylcholine transferase (ChAT), AChE, vesicular acetylcholine transporter (VAChT), and choline transporter (ChT) in the prefrontal cortex (PFC).

RESULTS

We found that anesthesia/surgery had no effects on the reference memory, but it impaired the working memory in adult mice. Meanwhile, we also found that the protein level of ChAT in PFC decreased significantly compared with that in control group. Donepezil pretreatment prevented working memory impairment and the decrease of the protein levels of ChAT induced by anesthesia/surgery.

CONCLUSION

These results suggest that anesthesia/surgery leads to working memory deficits in adult mice and central cholinergic system impairment is involved.

The interplay of BDNF-TrkB with NMDA receptor in propofol-induced cognition dysfunction : Mechanism for the effects of propofol on cognitive function

Background

The aim of the present study was to verify whether propofol impaired learning and memory through the interplay of N-methyl-D-aspartate (NMDA) receptor with brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling pathway.

Methods

120 Sprague-Dawley (SD) rats were randomly assigned into eight groups. Experimental drugs including saline, intralipid, propofol, N-methyl-D-aspartate (NMDA), 7,8-dihydroxyflavone (7,8-DHF), K252a and MK-801. Spatial learning and memory of rats were tested by the Morris water maze (MWM) test. The mRNA and protein expression were determined by immunohistochemistry, RT-PCR and western blot. Finally, hippocampus cells proliferation and apoptosis were examined by PCNA immunohistochemistry and TUNEL respectively.

Results

The memory and learning was diminished in the propofol exposure group, however, the impaired memory and learning of rats were improved with the addition of NMDA and 7,8-DHF, while the improvement of memory and learning of rats were reversed with the addition of K252a and MK-801. In addition, the mRNA and protein expression levels and hippocampus cells proliferation were the same trend with the results of the MWM test, while apoptosis in hippocampus was reversed.

Conclusion

The propofol can impair memory and learning of rats and induce cognition dysfunction through the interplay of NMDA receptor and BDNF-TrkB-CREB signaling pathway.

Comparison in anesthetic effects of propofol among patients with different ABO blood groups

Our study was aimed to investigate anesthetic effects of propofol in patients with different blood groups.A total of 72 participants were enrolled from patients arranged for surgeries of cholecystectomy, tonsillectomy, and spinal operation. Each blood group (A, B, AB, and O) contained 18 participants. Mean arterial pressure (MAP), heart rate (HR), and bispectral index (BIS) were assayed with Philips monitor. These indexes were observed before propofol anesthesia (T0), and then were recorded when concentration of propofol was 1 μg/mL (T1), 2 μg/mL (T2), 3 μg/mL (T3), and 4 μg/mL (T4). The differences in MAP, HR, and BIS at T0 among groups were compared with the χ test. Multiple comparisons were adopted to calculate the differences in MAP, HR, and BIS between groups at T1, T2, T3, and T4.No significant differences in age, sex, and weight of all groups were found (P > .05). Before propofol anesthesia (T0), all the participants exhibited no differences in MAP, HR, and BIS (P > .05). Subsequently, we found obvious differences in ΔMAP, ΔHR, and ΔBIS between groups. The patients in the B blood group showed highest ΔMAP and ΔHR at each time point (P < .05 for both). As for ΔBIS, patients in A blood group exhibited highest value at T3 and T4 (P < .05).The blood group remarkably affects the anesthetic effects of propofol.

Early childhood exposure to short periods of sevoflurane is not associated with later, lasting cognitive deficits

BACKGROUND

A detrimental effect of commonly used anesthetics on the neurodevelopmental and behavioral parameters has long been shown in young animals subjected to early childhood anesthesia. Epidemiologic studies suggest the possibility of a modestly elevated risk of adverse neurodevelopmental outcomes in children exposed to anesthesia during early childhood. However, these results are still preliminary and inconclusive.

AIM

To further elucidate the probability of occurrence of such adverse outcomes, we evaluated cognitive performance of children who underwent general anesthesia early in their childhood.

METHOD

One hundred and fifteen children aged 5-16 years with established glaucoma were included in the study. Of these, 68 children had a history of at least one general anesthesia with sevoflurane before age 3. Phonemic and semantic verbal fluency, and forward and backward digit span tests were performed to evaluate cognitive function in the study subjects.

RESULTS

The two-way anova revealed that all these variables showed significant changes in various age groups, but they were comparable among subjects with no, single, or multiple childhood anesthesia.

CONCLUSION

It can be concluded that brief periods of anesthesia with single anesthetic sevoflurane may be safe for children under age 3.

Sevoflurane Inhalation Accelerates the Long-Term Memory Consolidation via Small GTPase Overexpression in the Hippocampus of Mice in Adolescence

Sevoflurane exposure impairs the long-term memory in neonates. Whether the exposure to animals in adolescence affects the memory, however, has been unclear. A small hydrolase enzyme of guanosine triphosphate (GTPase) rac1 plays a role in the F-actin dynamics related to the synaptic plasticity, as well as superoxide production via reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. The current study was designed to examine whether sevoflurane exposure to mice in early adolescence modifies the long-term learning ability concomitantly with the changes in F-actin constitution as well as superoxide production in the hippocampus according to the levels of rac1 protein expression. Four-week-old mice were subjected to the evaluation of long-term learning ability for three days. On day one, each mouse was allowed to enter a dark chamber for five min to acclimatization. On day two, the procedure was repeated with the addition of an electric shock as soon as a mouse entered the dark chamber. All mice subsequently inhaled 2 L/min air with (Sevoflurane group) and without (Control group) 2.5% sevoflurane for three hours. On day three, each mouse was placed on the platform and retention time, which is the latency to enter the dark chamber, was examined. The brain removed after the behavior test, was used for analyses of immunofluorescence, Western immunoblotting and intracellular levels of superoxide. Sevoflurane exposure significantly prolonged retention time, indicating the enhanced long-term memory. Sevoflurane inhalation augmented F-actin constitution coexisting with the rac1 protein overexpression in the hippocampus whereas it did not alter the levels of superoxide. Sevoflurane exposure to 4-week-old mice accelerates the long-term memory concomitantly with the enhanced F-actin constitution coexisting with the small GTPase rac1 overexpression in the hippocampus. These results suggest that sevoflurane inhalation may amplify long-term memory consolidation via the increased cytoskeleton constitution in the hippocampus of animals in early adolescence.

Electroacupuncture Ameliorates Propofol-Induced Cognitive Impairment via an Opioid Receptor-Independent Mechanism

While general anesthesia is known to induce cognitive deficits in elderly and pediatric patients, its influence on adults is less well-characterized. The present study was designed to evaluate the influence of propofol on the learning and memory of young adult rats, as well as the potential neuroprotective role of electroacupuncture (EA) in propofol-induced cognitive impairment. Intravenous anesthesia with propofol was administered to young adult male Sprague–Dawley (SD) rats for 6 h, and EA was administered three times before and after anesthesia. The Morris Water Maze (MWM) test was conducted to determine the rat’s cognitive performance following the anesthesia treatment. Our results showed that propofol induced obvious cognitive impairment in young adult rats, which could be ameliorated by multiple EA treatments. Moreover, the decreased level of phosphorylated glycogen synthase kinase 3 β (pGSK-3β) in the CA1 region of the hippocampus accompanying the cognitive impairment was also reversed by EA treatment. Further experiments demonstrated that neither 2 nor 10 mg/kg (I.P.) naloxone blocked the effect of EA, indicating that the neuroprotective effect of EA on propofol-induced cognitive impairment was not mediated via the opioid receptors. The present study suggests that EA could ameliorate the cognitive impairment induced by prolonged anesthesia with propofol in young adult rats, which is likely associated with pGSK-3β levels in the CA1 independently of opioid receptors. These findings imply that EA may be used as a potential neuroprotective therapy for post-operative cognitive dysfunction (POCD).

Short-Term Changes in Postoperative Cognitive Function in Children Aged 5 to 12 Years Undergoing General Anesthesia: A Cohort Study

Due to the neurotoxicity effects of general anesthesia (GA) and sedatives found in animal studies, there is a general recommendation to avoid nonurgent surgical procedures requiring anesthesia in children younger than 3 years of age. The aim of this study was to determine the incidence of anesthesia-related postoperative cognitive dysfunction (POCD) on the first day (Day 1) and at 6 weeks after elective noncardiac surgery in school-age children.This was a prospective cohort study of 118 children undergoing GA and 126 age-matched controls of school children aged 5 to 12 years. All children were given a panel of 4 neuropsychological assessments (Hong Kong List Learning for verbal memory, Visual Matching for processing speed, Visual Memory, and General Comprehension Skill from the Hong Kong Wechsler Intelligence Scale for Children). The primary outcome was the incidence of POCD on Day 1 and at 6 weeks after surgery. POCD was defined as when at least 2 of the 4 cognitive function tests showed individual Z-scores ≤-1.96 or a combined Z-score ≤-1.96.Using the combined Z-score definition, the incidence of POCD in the GA group on Day 1 and at 6 weeks were 5.1% (95% confidence interval [CI]: 2.1-10.3) and 3.4% (95% CI: 1.1-8.0), respectively. No POCD was found using the other definition. The incidences of decline and improvement in neuropsychological tests were similar between groups over time except for a higher risk in visual matching impairment in the anesthesia group (11.9%) versus control group (1.6%) on Day 1 (P < 0.01). The adjusted relative risk ratio of postoperative cognitive decline to improvement between groups on Day 1 and at 6 weeks were 0.85 (95% CI: 0.10-7.05) and 0.45 (95% CI: 0.04-4.84), respectively. The observed risk of POCD is assumed to apply to current drugs and techniques used in GA.In conclusion, the incidence of POCD was low. GA was associated with a transient effect on visual matching. When using the widely accepted Z-score definitions and relative risk ratio methodology, we found no anesthesia-related POCD per se in school-age children.

Neuroprotective Effects Against POCD by Photobiomodulation: Evidence from Assembly/Disassembly of the Cytoskeleton

Postoperative cognitive dysfunction (POCD) is a decline in memory following anaesthesia and surgery in elderly patients. While often reversible, it consumes medical resources, compromises patient well-being, and possibly accelerates progression into Alzheimer's disease. Anesthetics have been implicated in POCD, as has neuroinflammation, as indicated by cytokine inflammatory markers. Photobiomodulation (PBM) is an effective treatment for a number of conditions, including inflammation. PBM also has a direct effect on microtubule disassembly in neurons with the formation of small, reversible varicosities, which cause neural blockade and alleviation of pain symptoms. This mimics endogenously formed varicosities that are neuroprotective against damage, toxins, and the formation of larger, destructive varicosities and focal swellings. It is proposed that PBM may be effective as a preconditioning treatment against POCD; similar to the PBM treatment, protective and abscopal effects that have been demonstrated in experimental models of macular degeneration, neurological, and cardiac conditions.