Anesthetic Immunomodulation of the Neuroinflammation in Postoperative Cognitive Dysfunction

Effects of neostigmine on postoperative neurocognitive dysfunction: a systematic review and meta-analysis

Introduction

Postoperative neurocognitive dysfunction (PND) is a common and serious complication following surgery. Neostigmine, an acetylcholinesterase inhibitor commonly administered during anesthesia to reverse residual neuromuscular blockade, has been suggested in recent studies to potentially reduce the incidence of PND. However, findings have been inconsistent across studies. Therefore, this study conducts a systematic review and meta-analysis to evaluate the effect of neostigmine on PND.

Methods

We conducted a comprehensive literature search across multiple databases, including PubMed, EmBase, Web of Science, Cochrane Library, Scopus, SinoMed, and CNKI, to identify all relevant studies for inclusion. We included randomized controlled trials and cohort studies in our analysis. The risk of bias was assessed using the Risk of Bias 2 tool for randomized trials and the ROBINS-I tool for cohort studies.

Results

A total of 11 studies were included in this analysis, consisting of 8 randomized controlled trials and 3 cohort studies. The incidence of PND was significantly lower in the neostigmine group compared to the control group (log(OR): -0.54, 95% CI [-1.04, -0. 05]; OR: 0.58, 95% CI: [0.35, 0.95], p = 0.03, I2 = 81.95%). Sensitivity analysis led to the exclusion of one cohort study. Consequently, the final meta-analysis comprised 10 studies, encompassing a total of 50,881 participants. The results indicate that the incidence of PND was significantly lower in the neostigmine group compared to the control group (log(OR):-0. 27, 95% CI [-0.47, -0. 08]; OR: 0.76, 95% CI: [0.62, 0.91], p = 0.01, I2 = 2.50%). However, Meta-analysis of RCTs and cohort studies showed no significant difference. Subgroup analysis indicated that neostigmine reduced the incidence of delayed neurocognitive recovery (dNCR), but its impact on POD was unclear, with no significant association to nausea and vomiting. These findings suggest that neostigmine may reduce the risk of PND, but caution is needed in interpretation.

Conclusion

Neostigmine may have a potential positive effect in reducing the incidence of PND. However, no statistical difference was observed when meta-analyses were performed separately for randomized controlled trials (RCTs) and cohort studies. Given the limited number of studies available and the limitations of the current research, further investigation is needed to clarify the impact of neostigmine on PND.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/view/CRD42024537647, Identifier CRD42024537647.

Intraoperative Dexmedetomidine for Prevention of Postoperative Cognitive Dysfunction and Delirium in Elderly Patients with Lobectomy: A Propensity Score-Matched, Retrospective Study

Purpose

This study aims to investigate whether dexmedetomidine could prevent postoperative cognitive dysfunction and delirium in patients with lobectomy.

Patients and Methods

Patients with lung cancer who underwent thoracoscopic lobectomy under general anesthesia were enrolled in this study and divided into dexmedetomidine group or control group. Propensity-score match (PSM) was used to reduce the bias and imbalance of confounding variables. After PSM, 87 patients in each group were included. Primary outcomes were postoperative cognitive function and delirium. Secondary outcomes include plasma TNF-α, IL-6, and S100 β protein concentrations. Adverse events were also collected.

Results

There were no significant differences in the demographic characteristics and hemodynamic parameters between the two groups. Compared with the control group, the MoCA scores were significantly higher (P<0.01), while the incidence of delirium (P<0.01) and the plasma TNF-α (P<0.01), IL-6 (P<0.01), and S100 β protein (P<0.01) concentrations were significantly lower in the dexmedetomidine group at 7 days post-operatively. The incidences of adverse events were similar between the two groups.

Conclusion

Dexmedetomidine could prevent postoperative cognitive dysfunction and delirium in patients with lobectomy by decreasing neuroinflammation.

Anesthesia, Anesthetics, and Postoperative Cognitive Dysfunction in Elderly Patients

Postoperative cognitive dysfunction (POCD) remains a major issue that worsens the prognosis of elderly surgery patients. This article reviews the current research on the effect of different anesthesia methods and commonly utilized anesthetics on the incidence of POCD in elderly patients, aiming to provide an understanding of the underlying mechanisms contributing to this condition and facilitate the development of more reasonable anesthesia protocols, ultimately reducing the incidence of POCD in elderly surgery patients.

The role of hormones in the pathogenesis and treatment mechanisms of delirium in ICU: The past, the present, and the future

Delirium is an acute brain dysfunction. As one of the common psychiatric disorders in ICU, it can seriously affect the prognosis of patients. Hormones are important messenger substances found in the human body that help to regulate and maintain the function and metabolism of various tissues and organs. They are also one of the most commonly used drugs in clinical practice. Recent evidences suggest that aberrant swings in cortisol and non-cortisol hormones might induce severe cognitive impairment, eventually leading to delirium. However, the role of hormones in the pathogenesis of delirium still remains controversial. This article reviews the recent research on risk factors of delirium and the association between several types of hormones and cognitive dysfunction. These mechanisms are expected to offer novel ideas and clinical relevance for the treatment and prevention of delirium.

Predicting postoperative delirium after hip arthroplasty for elderly patients using machine learning

BACKGROUND

Postoperative delirium (POD) is a common and severe complication in elderly hip-arthroplasty patients.

AIM

This study aims to develop and validate a machine learning (ML) model that determines essential features related to POD and predicts POD for elderly hip-arthroplasty patients.

METHODS

The electronic record data of elderly patients who received hip-arthroplasty surgery between January 2017 and April 2021 were enrolled as the dataset. The Confusion Assessment Method (CAM) was administered to the patients during their perioperative period. The feature section method was employed as a filter to determine leading features. The classical machine learning algorithms were trained in cross-validation processing, and the model with the best performance was built in predicting the POD. Metrics of the area under the curve (AUC), accuracy (ACC), sensitivity, specificity, and F1-score were calculated to evaluate the predictive performance.

RESULTS

476 Arthroplasty elderly patients with general anesthesia were included in this study, and the final model combined feature selection method mutual information (MI) and linear binary classifier using logistic regression (LR) achieved an encouraging performance (AUC = 0.94, ACC = 0.88, sensitivity = 0.85, specificity = 0.90, F1-score = 0.87) on a balanced test dataset.

CONCLUSION

The model could predict POD with satisfying accuracy and reveal important features of suffering POD such as age, Cystatin C, GFR, CHE, CRP, LDH, monocyte count, history of mental illness or psychotropic drug use and intraoperative blood loss. Proper preoperative interventions for these factors could reduce the incidence of POD among elderly patients.

Identification of circRNA-miRNA-mRNA networks to explore the molecular mechanism and immune regulation of postoperative neurocognitive disorder

Postoperative neurocognitive disorder (PND) is a common complication in older patients. However, its pathogenesis has still remained elusive. Recent studies have shown that circular RNA (circRNA) plays an important role in the development of neurodegenerative diseases, such as PND after surgery. CircRNA, as a competitive endogenous RNA (ceRNA), mainly acts as a molecular sponge for miRNA to "adsorb" microRNA (miRNA) and to reduce the inhibitory effects of miRNAs on target mRNA. The sequencing data of circRNA were obtained from the Gene Expression Omnibus (GEO) database. By bioinformatic methods, circAtlas, miRDB, miRTarBase and miRwalk databases were applied to construct circRNA-miRNA-mRNA networks and screen differentially expressed mRNAs. To improve the accuracy of the data, we randomly divided aging mice into control (non-PND group) and PND groups, and used high-throughput sequencing to analyze their brain hippocampal tissue for analysis. Three key genes were cross-detected in the data of both groups, which were Unc13c, Tbx20 and St8sia2 (as hub genes), providing new targets for PND treatment. According to the results of the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, immune cell infiltration analysis, gene set enrichment analysis (GSEA), Connectivity Map (CMap) analysis, quantitative real-time polymerase chain reaction (qRT-PCR), the genes that were not related to the central nervous system were removed, and finally, mmu_circ_0000331/miR-1224-3p/Unc13c and mmu_circ_0000406/miR-24-3p/St8sia2 ceRNA networks were identified. In addition, the CMap method was used to select the top 4 active compounds with the largest negative correlation absolute values, including cimaterol, Rucaparib, FG-7142, and Hydrocortisone.

The effect of neostigmine on postoperative delirium after colon carcinoma surgery: a randomized, double-blind, controlled trial

Background

Postoperative delirium (POD) is a critical complication in patients accepting colon carcinoma surgery. Neostigmine, as a cholinesterase inhibitor, can enhance the transmission of cholinergic transmitters in synaptic space, and play an important role in maintaining the normal level of cognition, attention and consciousness. The objective of this study was to investigate the effect of neostigmine on POD and clinical prognosis.

Methods

A randomized, double-blind controlled trial was implemented in Qingdao Municipal Hospital Affiliated to Qingdao University. A total of 454 patients aged 40 to 90 years old accepted colon carcinoma surgery were enrolled between June 7, 2020, and June 7, 2021, with final follow-up on December 8, 2021. Patients were randomly assigned to two groups: the neostigmine group (group N) and the placebo group (group P), the patients in group N were injected with 0.04 mg/kg neostigmine and 0.02 mg/kg atropine intravenously. The primary endpoint was the incidence of POD, researchers evaluated the occurrence of POD by the Confusion Assessment Method (CAM) twice daily (at 10 a.m. and 2 p.m.) during the first 7 postoperative days, POD severity was assessed by the Memorial Delirium Assessment Scale (MDAS). The secondary endpoints were the extubating time, postanesthesia care unit (PACU) time, the incidence of various postoperative complications, length of hospital stays, and 6 months postoperative mortality.

Results

The incidence of POD was 20.20% (81/401), including 19.39% (38/196) in group N and 20.98% (43/205) in group P. There was no significant statistical significance in the incidence of POD between group N and group P (P > 0.05); Compared to group P, the extubating time and PACU time in group N were significantly reduced (P < 0.001), the incidence of postoperative pulmonary complications (POPCs) decreased significantly in group N (P < 0.05), while no significant differences were observed in postoperative hospital stay and mortality in 6 months between the two groups (P > 0.05).

Conclusion

For patients accepted colon carcinoma surgery, neostigmine did not significantly reduce the incidence of POD, postoperative mortality and postoperative hospital stay, while it indeed reduced the extubating time, PACU time and the incidence of POPCs.

Trial registration

The randomized, double-blind, controlled trial was registered retrospectively at www.chictr.org.cn on 07/06/2020 (ChiCTR2000033639).

Influence of dexmedetomidine on postoperative cognitive dysfunction in the elderly: A meta-analysis of randomized controlled trials

INTRODUCTION

Dexmedetomidine (Dex) is suggested to be neuroprotective. However, influence of Dex on postoperative cognitive dysfunction (POCD) in the elderly remains unknown.

METHODS

We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of Dex on POCD. Relevant studies were obtained by search of PubMed, Embase, and Cochrane's Library databases. A random-effect model was used to pool the results.

RESULTS

Fourteen RCTs including 1626 adults of 60 years or older who received surgery with general anesthesia were included. Because methodologically diverse scales were used for POCD, eight RCTs with POCD diagnosed with Mini-Mental State Examination (MMSE) were included in the meta-analysis, while the remaining six RCTs with POCD diagnosed with other scales were qualitative synthesized. Pooled results of RCTs with MMSE showed that Dex significantly reduced the incidence of POCD (risk ratio: 0.47, 95% confidence interval: 0.37-0.60, p < 0.001) with no significant heterogeneity (I2  = 0%) or publication bias (p for Egger's regression test = 0.579). For the remaining six RCTs with POCD diagnosed with other scales, three of them showed that Dex was associated with a significantly lower incidence of POCD, while the other three RCTs did not show a significant difference.

CONCLUSIONS

Dex is associated with a reduced risk of POCD in elderly patients receiving surgeries with general anesthesia, and the results were mainly obtained in studies with POCD diagnosed with MMSE. Based on these findings, Dex may be considered as a preventative measure for POCD in elderly patients.

Midazolam impacts acetyl-And butyrylcholinesterase genes: An epigenetic explanation for postoperative delirium?

Midazolam is a widely used short-acting benzodiazepine. However, midazolam is also criticized for its deliriogenic potential. Since delirium is associated with a malfunction of the neurotransmitter acetylcholine, midazolam appears to interfere with its proper metabolism, which can be triggered by epigenetic modifications. Consequently, we tested the hypothesis that midazolam indeed changes the expression and activity of cholinergic genes by acetylcholinesterase assay and qPCR. Furthermore, we investigated the occurrence of changes in the epigenetic landscape by methylation specific PCR, ChiP-Assay and histone ELISA. In an in-vitro model containing SH-SY5Y neuroblastoma cells, U343 glioblastoma cells, and human peripheral blood mononuclear cells, we found that midazolam altered the activity of acetylcholinesterase /buturylcholinesterase (AChE / BChE). Interestingly, the increased expression of the buturylcholinesterase evoked by midazolam was accompanied by a reduced methylation of the BCHE gene and the di-methylation of histone 3 lysine 4 and came along with an increased expression of the lysine specific demethylase KDM1A. Last, inflammatory cytokines were not induced by midazolam. In conclusion, we found a promising mechanistic link between midazolam treatment and delirium, due to a significant disruption in cholinesterase homeostasis. In addition, midazolam seems to provoke profound changes in the epigenetic landscape. Therefore, our results can contribute to a better understanding of the hitherto poorly understood interactions and risk factors of midazolam on delirium.

Relationship between Artificial Intelligence-Based General Anesthetics and Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) refers to the complications of the central nervous system before and after surgery in patients without mental disorders. Many studies have shown that surgical anesthesia may cause POCD, especially in elderly patients. This article aims to study the relationship between artificial intelligence-based general anesthetics and postoperative cognitive dysfunction. This article first describes and classifies artificial intelligence, introduces its realization method, machine learning algorithms, and briefly introduces the basic principles of regression and classification methods in machine learning; then, the principles and techniques of general anesthetics are proposed. The pathogenesis of postoperative cognitive dysfunction (POCD) is explained in detail. Finally, the effect of anesthetics on postoperative cognitive dysfunction is obtained from both inhaled anesthetics and intravenous anesthetics. The impact on postoperative cognitive function is explained. The experimental results in this article show that there is no statistically significant difference in the two groups of patients' age, gender ratio, body mass index, education level, preoperative comorbidities, and other general indicators. Through the use of EEG bispectral index monitors to monitor the depth of anesthesia and postoperative cognitive dysfunction, first, there was no obvious relationship between the occurrence of postoperative cognitive dysfunction at 1, 5, 10, and 50 days and discharge time. The comprehensive monitoring group can reduce the clinical dose of preventive medication and cis-atracurium and shorten the patient's recovery time, extubation time, and recovery time. In addition, it can also reduce the increase of serum protein S100β in elderly patients and reduce the incidence of early postoperative cognitive dysfunction.

Insulin-like growth factor-1 improves postoperative cognitive dysfunction following splenectomy in aged rats

Postoperative cognitive dysfunction (POCD) is a serious complication following anesthesia and operations in aged patients undergoing surgical intervention. It is characterized by temporary or permanent cognitive decline, memory impairment and deterioration in language comprehension and social adaption ability. Therefore, the development of POCD prevention and treatment tools has become an area of interest. The current study assessed the therapeutic effects of insulin-like growth factor-1 (IGF-1) on POCD in aged rats and explored the underlying mechanisms. Model rats underwent splenectomy under 1.5-2% isoflurane and mechanical ventilation. IGF-1 (50 µg/kg) was diluted in normal saline and administered by abdominal hypodermic injection daily from the operation to day 7 post-operation. Following splenectomy, the animals showed marked cognitive impairment as determined by the Morris water maze test. Hippocampal protein levels of amyloid precursor protein (APP), β-site APP-cleaving enzyme-1 (BACE-1), amyloid-β (Aβ), capase3, Bax and Bcl-2 were assessed by immunoblotting. Neuronal apoptosis in the hippocampus was analyzed using a TUNEL assay. The results demonstrated that the levels of APP, BACE-1, Aβ, caspase3 and Bax were increased following splenectomy, while the levels of Bcl2 were reduced at days 1, 3 and 7 post-operation in aged rats. However, IGF-1 downregulated APP, BACE-1, Aβ, capase3 and Bax, and upregulated Bcl2 at these time points following splenectomy. TUNEL staining revealed that administration of IGF-1 significantly reduced neuronal apoptosis in the hippocampal CA1 region following splenectomy. These results indicated that IGF-1 decreased Aβ-protein production and inhibited neuronal apoptosis in the hippocampus following splenectomy, subsequently alleviating POCD.

Repeated propofol exposure-induced neuronal damage and cognitive impairment in aged rats by activation of NF-κB pathway and NLRP3 inflammasome

BACKGROUND

Elderly patients receive propofol at regular intervals for sedation during gastrointestinal endoscopy. However, the link between cognition and intermittent propofol exposure remains unclear. Thus, we used aged rats to investigate the effect of propofol on cognition.

METHODS

The study included two parts. In the first part, aged (18-20 months old) male Sprague-Dawley rats underwent intermittent intraperitoneal injection of propofol (200 mg/kg) or intralipid, every 9 days or once a day. In the second part, some aged rats received intraperitoneal injection of Bay 11-7082 (1 mg/kg), a specific inhibitor of NF-κB, 30 min before propofol injection. Memory tests were performed to evaluate cognition 24 h after the entire treatment. The hippocampal neuronal damage was assessed by TUNEL staining. The hippocampal levels of p-NF-κB p65, NLRP3, caspase-1 p20, and cleaved caspase-3 were detected by western blotting. The hippocampal and serum levels of IL-1β, IL-6, and TNF-α were evaluated using ELISA.

RESULTS

There were no differences in the behavioral tests, hippocampal neuronal damage, and neuroinflammation between groups given intralipid and propofol treatment every 9 days. However, repeated propofol treatment once a day promoted activation of NF-κB and the NLRP3 inflammasome, inducing cognitive impairment and neuroinflammation. Interestingly, pretreatment with Bay-11-7082 not only inhibited NF-κB/NLRP3 inflammasome activation, but also attenuated neuronal damage and cognitive dysfunction in aged rats exposed to daily propofol treatment.

CONCLUSIONS

Intermittent propofol treatment every 9 days may be safe for aged rats. However, propofol treatment once a day could impair the cognition of aged rats, partly through the activation of the NF-κB pathway and NLRP3 inflammasome, which may be a potential targets for the treatment of cognitive impairment in elderly patients.

Pathomechanisms of Non-Traumatic Acute Brain Injury in Critically Ill Patients

Delirium, an acute alteration in mental status characterized by confusion, inattention and a fluctuating level of arousal, is a common problem in critically ill patients. Delirium prolongs hospital stay and is associated with higher mortality. The pathophysiology of delirium has not been fully elucidated. Neuroinflammation and neurotransmitter imbalance seem to be the most important factors for delirium development. In this review, we present the most important pathomechanisms of delirium in critically ill patients, such as neuroinflammation, neurotransmitter imbalance, hypoxia and hyperoxia, tryptophan pathway disorders, and gut microbiota imbalance. A thorough understanding of delirium pathomechanisms is essential for effective prevention and treatment of this underestimated pathology in critically ill patients.

Major surgery induces acute changes in measured DNA methylation associated with immune response pathways

Surgery is an invasive procedure evoking acute inflammatory and immune responses that can influence risk for postoperative complications including cognitive dysfunction and delirium. Although the specific mechanisms driving these responses have not been well-characterized, they are hypothesized to involve the epigenetic regulation of gene expression. We quantified genome-wide levels of DNA methylation in peripheral blood mononuclear cells (PBMCs) longitudinally collected from a cohort of elderly patients undergoing major surgery, comparing samples collected at baseline to those collected immediately post-operatively and at discharge from hospital. We identified acute changes in measured DNA methylation at sites annotated to immune system genes, paralleling changes in serum-levels of markers including C-reactive protein (CRP) and Interleukin 6 (IL-6) measured in the same individuals. Many of the observed changes in measured DNA methylation were consistent across different types of major surgery, although there was notable heterogeneity between surgery types at certain loci. The acute changes in measured DNA methylation induced by surgery are relatively stable in the post-operative period, generally persisting until discharge from hospital. Our results highlight the dramatic alterations in gene regulation induced by invasive surgery, primarily reflecting upregulation of the immune system in response to trauma, wound healing and anaesthesia.

Age, preoperative higher serum cortisol levels, and lower serum acetylcholine levels predict delirium after percutaneous coronary intervention in acute coronary syndrome patients accompanied with renal dysfunction

BACKGROUND

The objective of the study is to investigate the incidence and risk factors of delirium after percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) patients accompanied with renal dysfunction.

MATERIALS AND METHODS

This was a prospective and cohort study, performed in a medical center from July 2014 to June 2017, which enrolled ACS patients accompanied with renal dysfunction who were treated with PCI. Univariate analysis and binary logistic regression analysis was used to determine the incidence and risk factors of delirium.

RESULTS

Data were analyzed from 119 patients. The 7-day incidence of delirium after PCI in ACS patients accompanied with renal dysfunction was 15.97% (n = 19/119). The binary logistic regression analysis results indicate that age (odd ratio [OR] 1.463; 95% confidence interval [CI] 1.070-2.001; P = 0.017), preoperative higher serum cortisol (COR) (OR 1.025; 95% CI 1.002-1.048; P = 0.030), and lower serum acetylcholine (Ach) (OR 0.965; 95% CI 0.937-0.993; P = 0.016) were significant differences in delirium and nondelirium groups.

CONCLUSIONS

Age, preoperative higher serum COR levels, and lower serum Ach levels were independent risk factors for delirium after PCI in ACS patients accompanied with renal dysfunction.

Dexmedetomidine suppresses sevoflurane anesthesia-induced neuroinflammation through activation of the PI3K/Akt/mTOR pathway

Background

Sevoflurane, an inhalational general anesthetic, has become one of the most widely used inhalational anesthetics in surgery. However, previous studies have found that sevoflurane anesthesia can trigger an inflammatory response, resulting in secondary damage. Dexmedetomidine (DEX), a highly-selective α adrenergic receptor agonist, is widely used as an anesthetic adjuvant in the clinic. In this study we investigated whether DEX was able to suppress sevoflurane-induced neuroinflammation.

Methods

The aim was to determine the mechanism of action of the suppressive effect of DEX using a rat model. Rats were randomly divided into a control group (n = 10), low-dose sevoflurane group (L-Sev; n = 10), high-dose sevoflurane group (H-Sev; n = 10), vehicle group (n = 10), DEX group (n = 10) and DEX + LY294002 (a specific inhibitor of PI3K) group (n = 10). The rats in vehicle, DEX and DEX + LY294002 groups were in the presence of high-dose sevoflurane exposure. Western blotting was used to measure the expression of proinflammatory cytokines (IL-6, IL-8, TNF-α) and the activity level of the phosphatidylinositol 3-hydroxy kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway.

Results

We found that sevoflurane anesthesia induced an increase in the levels of pro-inflammatory cytokines, while decreasing activation of the PI3K/Akt/mTOR pathway in both the cortex and hippocampus of rats. Treatment with DEX reduced pro-inflammatory cytokine levels and prevented inactivation of the PI3K/Akt/mTOR pathway. Moreover, LY294002, an inhibitor of the PI3K/Akt/mTOR pathway, reduced the anti-inflammatory activity of DEX.

Conclusions

These data suggest that the PI3K/Akt/mTOR pathway contributes to sevoflurane-induced neuroinflammation and that activation of PI3K/Akt/mTOR signaling by DEX could help reduce the neuroinflammatory effects of sevoflurane.

A novel understanding of postoperative complications: In vitro study of the impact of propofol on epigenetic modifications in cholinergic genes

Background

Propofol is a widely used anaesthetic drug with advantageous operating conditions and recovery profile. However, propofol could have long term effects on neuronal cells and is associated with post-operative delirium (POD). In this context, one of the contributing factors to the pathogenesis of POD is a reduction of cholinesterase activity. Accordingly, we investigated the effects of propofol on the methylation, expression and activity of cholinergic genes and proteins in an in-vitro model.

Results

We found that propofol indeed reduced the activity of AChE / BChE in our in-vitro model, without affecting the protein levels. Furthermore, we could show that propofol reduced the methylation of a repressor region of the CHRNA7 gene without changing the secretion of pro–or anti-inflammatory cytokines. Lastly, propofol changed the expression patterns of genes responsible for maintaining the epigenetic status of the cell and accordingly reduced the tri-methylation of H3 K27.

Conclusion

In conclusion we found a possible functional link between propofol treatment and POD, due to a reduced cholinergic activity. In addition to this, propofol changed the expression of different maintenance genes of the epigenome that also affected histone methylation. Thus, propofol treatment may also induce strong, long lasting changes in the brain by potentially altering the epigenetic landscape.

A Mouse Model of Hepatic Ischemia-Reperfusion Injury Demonstrates Potentially Reversible Effects on Hippocampal Neurons and Postoperative Cognitive Function

Background

This study aimed to investigate cognitive function, hippocampal neuronal changes, and the expression of inflammatory cytokines in a mouse model of hepatic ischemia-reperfusion injury.

Material/Methods

Sixty mice were divided into the sham group, which underwent surgery without vascular occlusion; the I/R1 group, with occlusion of the left hepatic artery and portal vein for 20 min, and reperfusion for 30 min; and the I/R2 group, with occlusion of the left hepatic artery and portal vein for 40 min, and reperfusion for 30 min. At postoperative day 4 and 11, ten mice from each group underwent the Morris water maze (MWM) task. Hippocampal tissues were stained for Nissl bodies. Expression of nuclear factor-κB (NF-κB) and choline acetyltransferase (ChAT) were quantified by immunohistochemistry. Serum tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured by enzyme-linked immunosorbent assay (ELISA).

Results

Groups I/R1 and I/R2 showed a significantly increased latency in the MWM test between days 5–9, compared with the sham group (P<0.05), with no difference by day 11; the I/R2 group had an initial lower crossing frequency (P<0.05), with no difference by day 18. The I/R2 group showed reduced numbers of Nissl bodies in hippocampal neurons. The I/R1 and I/R2 groups had increased expression of NF-κB, TNF-α, and IL-1β and decreased ChAT. No differences between the groups were found in levels of NF-κB, TNF-α, IL-1β, or ChAT by day 18.

Conclusions

A mouse model of hepatic ischemia-reperfusion injury showed transient and reversible cognitive dysfunction, changes in hippocampal neurons, and expression of inflammatory cytokines.

Inhibiting the NLRP3 Inflammasome With MCC950 Ameliorates Isoflurane-Induced Pyroptosis and Cognitive Impairment in Aged Mice

Nod-like receptor protein 3 (NLRP3) inflammasome activation has been implicated in the pathogenesis of general anesthesia (GA)-induced neuroinflammation and cognitive impairment in aged rodents. However, the cellular basis for cognitive impairment is still not fully understood, and effective pharmacologic agents targeting the NLRP3 inflammasome during GA are lacking. This study explores the protective effects of the NLRP3 inflammasome inhibitor MCC950 on pyroptosis and cognitive impairment in aged mice exposed to isoflurane. Seventy-two 15-month-old male C57BL/6 mice were randomized to receive 2 h of 1.5% isoflurane plus 30% oxygen (O₂) or 30% O₂ alone, respectively. MCC950 (10 mg/kg) or vehicle was intraperitoneally administered 30 min before gas inhalation. Brain tissues were harvested for histochemical analysis and biochemical assays. Learning and memory abilities were evaluated by behavioral tests. We found that isoflurane GA caused upregulations of hippocampal NLRP3, cleaved caspase-1, interleukin-1β (IL-1β), and IL-18 and the activation of pyroptosis, which is NLRP3 inflammasome-dependent; this consequently gave rise to neuronal damage and cognitive impairment in aged mice. Interestingly, pretreatment with NLRP3 inflammasome inhibitor MCC950 not only provided a neuroprotective effect against the inflammasome activation but also ameliorated pyroptosis and cognitive impairment in aged mice exposed to isoflurane. Our data demonstrate that pyroptosis is involved in NLRP3 inflammasome-mediated isoflurane-induced cognitive impairment in aged mice and suggest that inhibiting the NLRP3 inflammasome with MCC950 may have clinically therapeutic benefits for elderly patients undertaking GA.

Postoperative delirium in the elderly: the potential neuropathogenesis

Postoperative delirium (POD) is a neurobehavioral syndrome caused by dysfunction of neural activity mainly in elderly people. POD is not uncommon, but under-recognized, and often serious. Multifactorial causes including aging, acetylcholine deficiency, sleep deprivation and intraoperative hypoxia have been proposed attempting to explain the processes leading to the development of POD. To date, however, no specific pathophysiologic mechanism has been identified. Here, we summarize the five most prominent theories (neuronal aging, neuroinflammation, neurotransmitter imbalance, neuroendocrine activation, and network connectivity change) to explain the development of delirium. Understanding of the neuropathogenesis of delirium will help focus future research, and assist in developing prophylactic and treatment strategies.

Sevoflurane anesthesia alters cognitive function by activating inflammation and cell death in rats

The present study was designed to investigate the effects of sevoflurane inhalation anesthesia on the cognitive function of rats and to investigate the molecular mechanisms mediating this effect. A total of 100 healthy male Sprague-Dawley rats were divided into four groups: i) Control (air inhalation), ii) low-dose (1.5% sevoflurane inhalation for 2 h), iii) high-dose (3% sevoflurane inhalation for 2 h), and iv) nimodipine group (3% sevoflurane inhalation for 2 h + nimodipine). Sevoflurane inhalation anesthesia resulted in cognitive dysfunction in a dose-dependent manner. Sevoflurane also upregulated the expression of tumour necrosis factor-α (TNF-α), interleukin (IL) −6, −8, and Caspase-3 in the hippocampus. The intervention with nimodipine partially recovered the cognitive function and the abnormal expression of TNF-α, IL-6, IL-8, and Caspase-3 induced by sevoflurane. The results showed that the cognitive dysfunction caused by sevoflurane inhalation in rats may be related to the activation of inflammatory and apoptotic pathways. The neuroprotective effect of nimodipine suggests that abnormal calcium transport is partially responsible for the sevoflurane toxicity.