Postoperative cognitive dysfunction, Alzheimer's disease, and anesthesia

Nanotherapeutics for Alleviating Anesthesia-Associated Complications

Current management of anesthesia-associated complications falls short in terms of both efficacy and safety. Nanomaterials with versatile properties and unique nano-bio interactions hold substantial promise as therapeutics for addressing these complications. This review conducts a thorough examination of the existing nanotherapeutics and highlights the strategies for developing prospective nanomedicines to mitigate anesthetics-related toxicity. Initially, general, regional, and local anesthesia along with the commonly used anesthetics and related prevalent side effects are introduced. Furthermore, employing nanotechnology to prevent and alleviate the complications of anesthetics is systematically demonstrated from three aspects, that is, developing 1) safe nano-formulization for anesthetics; 2) nano-antidotes to sequester overdosed anesthetics and alter their pharmacokinetics; 3) nanomedicines with pharmacodynamic activities to treat anesthetics toxicity. Finally, the prospects and challenges facing the clinical translation of nanotherapeutics for anesthesia-related complications are discussed. This work provides a comprehensive roadmap for developing effective nanotherapeutics to prevent and mitigate anesthesia-associated toxicity, which can potentially revolutionize the management of anesthesia complications.

Effect of intranasal insulin administration on postoperative delirium prevention in elderly cardiac surgery patients: study protocol for a multicenter, double-blind, randomized, controlled trial

BACKGROUND

Postoperative delirium (POD) is a complication after surgery which leads to worse outcomes. The frequency of this syndrome is increasing as more elderly patients undergo major surgery. The frequency is around 10-25% but reaches as high as 50% for cardiac surgery. Although intranasal insulin (INI) administration of up to 160 units in patients with cognitive dysfunction and delirium has been shown to improve memory function and brain metabolism without complications such as hypoglycemia, it remains unknown whether INI prevents POD after cardiac surgery METHODS: A multicenter, double-blind, randomized, controlled trial will be conducted at University of Tsukuba Hospital and Tsukuba Medical Center Hospital, Japan, from July 1, 2023, to December 31, 2025. A total of 110 elderly patients (65 years old or older) undergoing cardiac surgery requiring cardiopulmonary bypass will be enrolled and randomly allocated to intranasal insulin or intranasal saline groups. The primary outcome is the incidence of POD within 7 days after surgery. Secondary outcomes include days and times of delirium, screening tests of cognitive function, pain scores, duration of postoperative tracheal intubation, and length of ICU stay.

DISCUSSION

The present objective is to assess whether 80 IU INI administration during surgery prevents POD after cardiac surgery. The results may provide strategic choices to prevent POD in patients with cardiac surgery requiring cardiopulmonary bypass.

TRIAL REGISTRATION

The trial was registered with the Japan Registry for Clinical Trials with identifier jRCTs031230047  on April 21, 2023.

Effects of anterior approach to quadratus lumborum block on postoperative cognitive function following hip surgery in older people: a randomized controlled clinical trial

BACKGROUND

Peripheral nerve block, including the quadratus lumborum block (QLB), has been used for postoperative analgesia in hip surgery. However, the effects of QLB on cognitive function after hip surgery remain unknown. This study aimed to assess the effects of the anterior approach to QLB on postoperative cognitive function in older people undergoing hip surgery.

METHODS

Sixty older people who underwent hip surgery from May 2021 to May 2022 were randomly divided into the QLB (n = 30) and control groups (n = 30). The Montreal Cognitive Assessment (MoCA) score (mean ± SD) was measured one day preoperatively and seven and 30 days postoperatively. The frequency (%) of postoperative cognitive dysfunction (POCD) was examined seven and 30 days postoperatively. The visual analog scale (VAS) scores at rest and Bruggrmann comfort scale (BCS) scores [Median (IQR)] 6 h (t1), 12 h (t2), 24 h (t3), and 48 h (t4) after surgery were assessed. The plasma high mobility group box protein 1 (HMGB1) and levels of interleukin-6 (IL-6) (mean ± SD) were evaluated 1 h preoperatively (baseline) and 24 h postoperatively (day 1). The requirement for rescue analgesia [Median (IQR)], time to first off-bed activity (mean ± SD), and adverse effects after surgery were also recorded.

RESULTS

Compared with the control group, the frequency of POCD was significantly lower in the QLB group seven days postoperatively (10.7% vs. 34.5%, P = 0.033), but no difference at 30 days postoperatively (3.6% vs. 10.3%, P = 0.319). There was no significant difference in MoCA scores between the two groups at one day preoperatively and 30 days postoperatively. However, the MoCA scores at seven days postoperatively were higher in the QLB group than in the control group (27.4 ± 1.81 vs. 26.4 ± 1.83, P = 0.043). In the QLB group, the VAS scores at t1, t2, and t3 were lower [3(2-4) vs. 4(3-4), P = 0.028; 3(2-3) vs. 4(3-5), P = 0.009; 2(1-3) vs. 2(2-3), P = 0.025], and the BCS scores at t1, t2, and t3 were higher than those in the control group [3(1-3) vs. 1(1-2), P = 0.006; 3(2-3) vs. 2(1-3), P = 0.011; 3(2-4) vs. 2(2-3), P = 0.041]. The patients in the QLB group reported significantly fewer requirements for rescue analgesia [0(0-1) vs. 1(0-2), P = 0.014]. The plasma levels of HMGB1 and IL-6 at 24 h postoperatively in the QLB group were significantly lower than in the control group (749.0 ± 185.7 vs. 842.1 ± 157.9, P = 0.046; 24.8 ± 8.1 vs. 31.9 ± 5.5, P < 0.001). The time to first off-bed activity from the end of surgery was shorter in the QLB group (25.3 ± 5.3 vs. 29.7 ± 6.9, P = 0.009). There was no significant difference in the incidence of postoperative complications between the two groups.

CONCLUSIONS

Anterior QLB given to older people undergoing hip surgery could promote early postoperative cognitive function recovery, provide adequate postoperative analgesia, and inhibit the release of inflammatory factors.

TRIAL REGISTRATION

Chictr.org.cn identifier ChiCTR2000040724 (Date of registry: 08/12/2020, prospectively registered).

Effects of dexmedetomidine on early cognitive function in elderly patients after abdominal surgery: a meta-analysis

INTRODUCTION

This meta-analysis aims to investigate the effect of dexmedetomidine (Dex) on postoperative cognitive dysfunction (POCD) in elderly patients undergoing abdominal surgery under general anesthesia.

EVIDENCE ACQUISITION

Six online databases were searched for studies on the effects of Dex on POCD in elderly patients (≥60 years) who underwent abdominal surgery under general anesthesia. The experimental group was treated with Dex and the control group with normal saline. The retrieval period was from the database's inception to March 2023. Stata 15.0 statistical software was utilized to analyze the data.

EVIDENCE SYNTHESIS

In total, 14 studies were entered into this meta-analysis, including 675 patients. On the first, third, and seventh days after surgery, the Mini-Mental State Examination (MMSE) scores in the experimental group were significantly higher than those in the controls (first day: weighted mean difference [WMD] = 2.52, 95% CI: 1.13~3.90, P<0.001; third day: WMD=2.58, 95% CI: 0.76~4.40, P=0.005; seventh day: WMD=1.43, 95% CI: 0.57~2.29, P=0.001). On the first day after surgery, there was a lot less cognitive dysfunction in the Dex group than in the controls (odds ratio [OR] = 0.25, 95% CI: 0.15~0.42, P<0.001).

CONCLUSIONS

Dex administered intraoperatively can enhance early cognitive function in elderly patients undergoing abdominal surgery.

Retinoic Acid Receptor Is a Novel Therapeutic Target for Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) is a clinical syndrome characterizing by cognitive impairments in the elderly after surgery. There is limited effective treatment available or clear pathological mechanisms known for this syndrome. In this study, a Connectivity Map (CMap) bioinformatics model of POCD was established by using differently expressed landmark genes in the serum samples of POCD and non-POCD patients from the only human transcriptome study. The predictability and reliability of this model were further supported by the positive CMap scores of known POCD inducers and the negative CMap scores of anti-POCD drug candidates. Most retinoic acid receptor (RAR) agonists were negatively associated with POCD in this CMap model, suggesting that RAR might be a novel target for POCD. Most importantly, acitretin, a clinically used RAR agonist, significantly inhibited surgery-induced cognitive impairments and prevented the reduction in RARα and RARα-target genes in the hippocampal regions of aged mice. The study denotes a reliable CMap bioinformatics model of POCD for future use and establishes that RAR is a novel therapeutic target for treating this clinical syndrome.

Postoperative serum CHI3L1 level is associated with postoperative cognitive dysfunction in elderly patients after hip fracture surgery: A prospective observational study

Objectives

Postoperative cognitive dysfunction (POCD) is a common postoperative complication in older patients. Chitinase-3-like-1 protein (CHI3L1) is identified as a neuroinflammatory biomarker and impairs cognitive function. This study aimed to evaluate the association between serum levels of CHI3L1 and POCD and explore the levels of interleukin-6 (IL-6), IL-1β and C-reactive protein (CRP) in the elderly after total hip arthroplasty (THA).

Patients and methods

A total of 76 elderly patients undergoing THA were enrolled in the prospective observational study. Serum CHI3L1 levels were measured 1 day before and 1 day after surgery and other perioperative factors were also noted. The correlations between mediators of inflammation in the two groups were compared via Spearman correlation coefficients. The receiver operating characteristic (ROC) curves were implemented to analyze the predictive values of serum CHI3L1 and other inflammatory factors for POCD. And factors associated with POCD were analyzed by univariate and multivariate logistics.

Results

POCD was observed in 31.6% of patients 1 week after surgery. Postoperative serum CHI3L1 levels were higher in POCD patients than in non-POCD patients [1348.26(778.46-1889.77) VS 2322.86(1686.88-2517.35) ng/ml, P < 0.001]. Postoperative serum CHI3L1 level was positively correlated with postoperative IL-6 level (r = 0.284, P = 0.013). Compared with IL-6, IL-1β, and CRP, postoperative CHI3L1 level has the highest predictive value for POCD with the area under the curve (AUC) value of 0.779 according to the ROC curve. By the multivariate logistic regression analysis, elevated postoperative serum CHI3L1 level was found to be an independent risk factor for POCD 1 week after surgery (odds ratio = 1.204, 95% confidence interval = 1.087-1.332, P = 0.001).

Conclusion

Postoperative elevated serum CHI3L1 level was significantly associated with the incident of POCD, and positively correlated with postoperative IL-6 level in the elderly after THA. This biomarker may have potential utility for further elucidating the etiology of POCD.

The Anaesthetics Isoflurane and Xenon Reverse the Synaptotoxic Effects of Aβ1-42 on Megf10-Dependent Astrocytic Synapse Elimination and Spine Density in Ex Vivo Hippocampal Brain Slices

It has been hypothesised that inhalational anaesthetics such as isoflurane (Iso) may trigger the pathogenesis of Alzheimer's disease (AD), while the gaseous anaesthetic xenon (Xe) exhibits many features of a putative neuroprotective agent. Loss of synapses is regarded as one key cause of dementia in AD. Multiple EGF-like domains 10 (MEGF10) is one of the phagocytic receptors which assists the elimination of synapses by astrocytes. Here, we investigated how β-amyloid peptide 1-42 (Aβ_1-42), Iso and Xe interact with MEGF10-dependent synapse elimination. Murine cultured astrocytes as well as cortical and hippocampal ex vivo brain slices were treated with either Aβ_1-42, Iso or Xe and the combination of Aβ_1-42 with either Iso or Xe. We quantified MEGF10 expression in astrocytes and dendritic spine density (DSD) in slices. In brain slices of wild type and AAV-induced MEGF10 knock-down mice, antibodies against astrocytes (GFAP), pre- (synaptophysin) and postsynaptic (PSD95) components were used for co-localization analyses by means of immunofluorescence-imaging and 3D rendering techniques. Aβ_1-42 elevated pre- and postsynaptic components inside astrocytes and decreased DSD. The combined application with either Iso or Xe reversed these effects. In the presence of Aβ_1-42 both anaesthetics decreased MEGF10 expression. AAV-induced knock-down of MEGF10 reduced the pre- and postsynaptic marker inside astrocytes. The presented data suggest Iso and Xe are able to reverse the Aβ_1-42-induced enhancement of synaptic elimination in ex vivo hippocampal brain slices, presumably through MEGF10 downregulation.

Сyclooxygenase-2 Inhibitor Parecoxib Reduces LPS-Induced Activation of BV2 Microglia Cells

We studied the inhibitory effect of cyclooxygenase-2 inhibitor parecoxib on LPS-induced activation of BV2 microglia cells. The optimal dose of parecoxib (80 μmol/liter) was evaluated by the Cell Counting Kit-8. The cells were divided into the following groups: control (intact cells without treatment); LPS (treatment with 1 μg/ml LPS for 6 h), and experimental (pretreatment with 80 μmol/liter parecoxib for 24 h followed by incubation with 1 μg/ml LPS for 6 h). Cell morphology and proliferation and the expression of NLRP3, caspase-1, pro-caspase-1, and IL-1β were assessed. LPS induced significant morphological changes and decreased proliferation of primary BV2 cells in comparison with the control. These changes were prevented by parecoxib pretreatment. LPS significantly increased NLRP3 inflammatory vesicle activation and expression of NLRP3, caspase-1, pro-caspase-1, and IL-1β in comparison with the control group; pretreatment with parecoxib prevented all these changes. Our results suggest that pretreatment with parecoxib inhibited LPS-induced activation of BV2 microglial cells and probably inhibited NLRP3 inflammasome activation.

Postoperative Cognitive Dysfunction and Alzheimer’s Disease: A Transcriptome-Based Comparison of Animal Models

Background

Postoperative cognitive dysfunction (POCD) is a common complication characterized by a significant cognitive decline. Increasing evidence suggests an association between the pathogenesis of POCD and Alzheimer’s disease (AD). However, a comprehensive understanding of their relationships is still lacking.

Methods

First, related databases were obtained from GEO, ArrayExpress, CNGB, and DDBJ repositories. De novo analysis was performed on the raw data using a uniform bioinformatics workflow. Then, macro- and micro-level comparisons were conducted between the transcriptomic changes associated with AD and POCD. Lastly, POCD was induced in male C57BL/6j mice and the hippocampal expression levels of mRNAs of interest were verified by PCR and compared to those in AD congenic models.

Results

There was a very weak correlation in the fold-changes in protein-coding transcripts between AD and POCD. Overall pathway-level comparison suggested that AD and POCD are two disease entities. Consistently, in the classical AD pathway, the mitochondrial complex and tubulin mRNAs were downregulated in both the POCD hippocampus and cortex. POCD and AD hippocampi might share the same pathways, such as tryptophan metabolism, but undergo different pathological changes in phagosome and transferrin endocytosis pathways. The core cluster in the hippocampal network was mainly enriched in mitosis-related pathways. The hippocampal expression levels of genes of interest detected by PCR showed good consistency with those generated by high throughput platforms.

Conclusion

POCD and AD are associated with different transcriptomic changes despite their similar clinical manifestations. This study provides a valuable resource for identifying biomarkers and therapeutic targets for POCD.

Dexmedetomidine Mitigates Microglial Activation Associated with Postoperative Cognitive Dysfunction by Modulating the MicroRNA-103a-3p/VAMP1 Axis

Surgery-induced microglial activation is critical in mediating postoperative cognitive dysfunction (POCD) in elderly patients, where the important protective effect of dexmedetomidine has been indicated. However, the mechanisms of action of dexmedetomidine during the neuroinflammatory response that underlies POCD remain largely unknown. We found that lipopolysaccharide (LPS) induced substantial inflammatory responses in primary and BV2 microglial cells. The screening of differentially expressed miRNAs revealed that miR-103a-3p was downregulated in these cell culture models. Overexpression of miR-103a-3p mimics and inhibitors suppressed and enhanced the release of inflammatory factors, respectively. VAMP1 expression was upregulated in LPS-treated primary and BV-2 microglial cells, and it was validated as a downstream target of miR-103-3p. VAMP1-knockdown significantly inhibited the LPS-induced inflammatory response. Dexmedetomidine treatment markedly inhibited LPS-induced inflammation and the expression of VAMP1, and miR-103a-3p expression reversed this inhibition. Moreover, dexmedetomidine mitigated microglial activation and the associated inflammatory response in a rat model of surgical trauma that mimicked POCD. In this model, dexmedetomidine reversed miR-103a-3p and VAMP1 expression; this effect was abolished by miR-103a-3p overexpression. Taken together, the data show that miR-103a-3p/VAMP1 is critical for surgery-induced microglial activation of POCD.

Hypercholesterolemia aggravates sevoflurane-induced cognitive impairment in aged rats by inducing neurological inflammation and apoptosis

We aimed to explore the effects of hypercholesterolemia on sevoflurane-induced cognitive impairment in aged rats and the underlying mechanism(s). Aged rats were administrated with high-fat diet, sevoflurane, or both. Thereafter, the plasma levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were evaluated. The Morris water maze task was performed to evaluate the spatial learning and memory ability of rats. Moreover, Nissl and Evans blue staining were conducted to test nerve damage and detect the blood-brain barrier permeability, respectively. The percentage of apoptotic cells was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The messenger RNA expression of inflammatory factors and protein expression of microglial activation markers and apoptosis-related proteins were tested by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, or western blot analysis, respectively. High-fat diet induced high levels of TC, TG, and LDL but decreased levels of HDL. However, sevoflurane had no effects on these levels. In contrast, sevoflurane significantly induced the impairment of learning and memory, nerve damage, neuroinflammatory damage, and neuronal apoptosis. Hypercholesterolemia exacerbated the sevoflurane-induced impairment in aged rats. These results suggested that hypercholesterolemia aggravates sevoflurane-induced cognitive impairment in aged rats, possibly by inducing neurological inflammation and apoptosis.

Impacts of oxidants and antioxidants on the emergence and progression of Alzheimer's disease

The brain shows a high sensitivity to oxidative stress (OS). Thus, the maintenance of homeostasis of the brain regarding the reduction-oxidation (redox) situation is crucial for the regular function of the central nervous systems (CNS). The imbalance between the reactive oxygen species (ROS) and the cellular mechanism might lead to the emergence of OS, causing profound cell death as well as tissue damages and initiating neurodegenerative disorders (NDDs). Characterized by the cytoplasmic growth of neurofibrillary tangles and extracellular β-amyloid plaques, Alzheimer's disease (AD) is a complex NDD that causes dementia in adult life with severe manifestations. Nuclear factor erythroid 2-related factor 2 (NRF2) is a key transcription factor that regulates the functional expression of OS-related genes and the functionality of endogenous antioxidants. In the case of oxidative damage, NRF2 is transferred to the nucleus and attached to the antioxidant response element (ARE) that enhances the sequence to initiate transcription of the cell-protecting genes. This review articulates various mechanisms engaged with the generation of active and reactive species of endogenous and exogenous oxidants and focuses on the antioxidants as a body defense system regarding the NRF2-ARE signaling path in the CNS.

Postoperative Effects of Dexmedetomidine on Serum Inflammatory Factors and Cognitive Malfunctioning in Patients with General Anesthesia

Objective

To investigate the effects of dexmedetomidine intervention on serum inflammatory factor concentration and postoperative cognitive malfunction in elderly patients with general anesthesia. Methodology. 174 patients with general anesthesia were selected, who were categorized into a control group (HC) and a dexmedetomidine group (HS) using the random number table method, with 87 patients in individual groups. The dexmedetomidine group was pumped intravenously with dexmedetomidine at a loading dose of 1 μg/kg before induction of anesthesia for 15 min, followed by continuous intravenous pumping at a rate of 0.4 μg/kg/h, and the dosing was stopped at 30 min before concluding the surgery. The control group was administered the identical dose of saline in the same manner. Interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) levels and MMES scores were tested at 1 h before and 24 h after anesthesia.

Results

Comparing to HC group, patients in the HS group had lower TNF-α and IL-6 levels at both scheduled points (P < 0.05).

Conclusion

Dexmedetomidine reduced the expression of inflammatory factors in elderly patients with general anesthesia and effectively reduced the incidence of postoperative cognitive dysfunction after general anesthesia surgery.

Elevation of miR-146a Inhibits BTG2/BAX Expression to Ameliorate Postoperative Cognitive Dysfunction Following Probiotics (VSL#3) Treatment

It has been reported that the gut microbiome modulates postoperative cognitive dysfunction (POCD), and that administration of probiotics (VSL#3) may effectively relieve POCD. In this study, we aimed to identify the underlying mechanism of VSL#3 in POCD. A mouse model of POCD was constructed in adult male C57BL/6 mice, which were then treated with VSL#3. VSL#3 exerted a protective role against POCD and resultant neuronal apoptosis. The expression of miR-146a was found to be downregulated in hippocampal tissues of POCD mice, while VSL#3 could restore its expression. Loss- and gain-function approaches were conducted to determine the roles of microRNA (miR)-146a, B-cell translocation gene 2 (BTG2), and Bcl-2-associated X protein (Bax) in post-operative effects on cognitive function and neuronal apoptosis. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were measured to determine oxidative stress in brain tissue. The dual-luciferase reporter gene assay identified that miR-146a could target BTG2 and negatively regulate its expression. BTG2 knockdown suppressed neuronal apoptosis and contributed to shortened time of latency, prolonged time of mice spent in the target quadrant, and reduced oxidative stress through downregulating Bax expression. Finally, VSL#3 treatment upregulated the expression of miR-146a to block BTG2/Bax axis and consequently inhibited neuronal apoptosis and reduced oxidative stress in POCD mice. Taken together, the study suggested that miR-146a-mediated suppression of BTG2/Bax contributed to the protective role of probiotics treatment against POCD.

Effect of sevoflurane on iron homeostasis and toxicity in the brain of mice

Sevoflurane (Sev), a commonly used volatile anesthetic, could induce nerve damage and cognitive deficiency. Oxidative stress induced by iron overload promotes nerve damage and cell apoptosis in the brain. This study revealed a new toxic mechanism of Sev to the brain occurred through the dysfunction of iron metabolism. Twelve-month-old C57BL/6 mice were randomly assigned to the following three groups: control group; 2% Sev (6 h) group; and Sev plus iron deficiency group. Iron levels and iron metabolism-related proteins and apoptosis-related factors in hippocampus and cortex tissues were detected by using synchrotron radiation micro-X-ray fluorescence (μ-XRF) and western blotting. Our results showed that a decline in cognitive function was observed in mice treated with Sev. Sev significantly induced iron accumulation through upregulating ferritin and downregulating transferrin receptor 1 which involved in ferroportin1 (Fpn1)/hepcidin pathway and increasing reactive oxygen species (ROS) and malondialdehyde (MDA) content of hippocampus and cortex. Sev aggravated BACE1 expression and Aβ accumulation. Changes in the ratio of Bcl2/Bax and Tau/p-Tau intensified the cell apoptosis in hippocampus and cortex tissues. Interestingly, the cognitive deficiency and neurotoxicity induced by Sev could be ameliorated significantly by feeding a low-iron diet to mice prior to anesthesia. The data uncovered a new lesion mechanism of Sev from the role of iron metabolism. This study also suggested that the reduction in iron levels could protect the brain against neurological damage induced by Sev.

Effect of quadratus lumborum block on postoperative cognitive function in elderly patients undergoing laparoscopic radical gastrectomy: a randomized controlled trial

Background

Quadratus lumborum block (QLB) is a novel and effective postoperative analgesia method for abdominal surgeries. However, whether QLB can affect early postoperative cognitive function by inhibiting surgical traumatic stress and the inflammatory response remains unclear. This study aimed to explore the effect of QLB on postoperative cognitive function in elderly patients undergoing laparoscopic radical gastrectomy.

Methods

Sixty-four elderly patients who underwent laparoscopic radical gastrectomy were randomly divided into the QLB group (Q group, n = 32) and control group (C group, n = 32). The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to measure cognitive function 1 day before and 7 days after surgery. Postoperative cognitive dysfunction (POCD) was defined as a decline of ≥ 1 SD in both tests. The visual analog scale (VAS) scores 6 h (T1), 24 h (T2), and 48 h (T3) after surgery were measured. The serum levels of high mobility group box protein 1 (HMGB1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were evaluated 1 day before surgery (baseline), and 1 day (day 1) and 3 days after surgery (day 3). The intraoperative remifentanil dosage, sufentanil consumption 24 h after surgery, recovery time from anesthesia, and adverse effects were also compared.

Results

POCD was present in two patients in the QLB group and eight patients in the C group 7 days after surgery (6.7 % vs. 27.6 %, P = 0.032). The MMSE and MoCA scores were similar in both groups preoperatively, and the two scores were higher in the QLB group than in the C group 7 days after surgery (P < 0.05). The VAS scores were significantly lower in the Q group at all times after surgery (P < 0.05). Compared with the C group, the levels of HMGB1, TNF-α, and IL-6 were significantly decreased 1 and 3 days after surgery in the QLB group (P < 0.05). The remifentanil consumption intraoperatively and sufentanil 24 h postoperatively were significantly lower in the QLB group (P < 0.05). The recovery time from anesthesia was shorter in the QLB group (P < 0.05). No severe adverse effects occurred in either group.

Conclusions

QLB could improve postoperative cognitive function in elderly patients undergoing laparoscopic radical gastrectomy. This may be related to the suppression of the inflammatory response after surgery.

Trial registration

Chictr.org.cn identifier ChiCTR1900027574 (Date of registry: 19/11/2019, prospectively registered).

Intranasal administration of 40 and 80 units of insulin does not cause hypoglycemia during cardiac surgery: a randomized controlled trial

PURPOSE

Intranasal insulin administration may improve cognitive function in patients with dementia and may prevent cognitive problems after surgery. Although the metabolic effects of intranasal insulin in non-surgical patients have been studied, its influence on glucose concentration during surgery is unknown.

METHODS

We conducted a randomized, double-blind, placebo-contolled trial in patients scheduled for elective cardiac surgery. Patients with type 2 diabetes mellitus (T2DM) and non-T2DM patients were randomly allocated to one of three groups (normal saline, 40 international units [IU] of intranasal insulin, and 80 IU intranasal insulin). Insulin was given after the induction of general anesthesia. Glucose and plasma insulin concentrations were measured in ten-minute intervals during the first hour and every 30 min thereafter. The primary outcome was the change in glucose concentration 30 min after intranasal insulin administration.

RESULTS

A total of 115 patients were studied, 43 of whom had T2DM. In non-T2DM patients, 40 IU intranasal insulin did not affect glucose concentration, while 80 IU intranasal insulin led to a statistically significant but not clinically important decrease in blood glucose levels (mean difference, 0.4 mMol·L^-1; 95% confidence interval, 0.1 to 0.7). In T2DM patients, neither 40 IU nor 80 IU of insulin affected glucose concentration. No hypoglycemia (< 4.0 mMol·L^-1) was observed after intranasal insulin administration in any patients. In non-T2DM patients, changes in plasma insulin were similar in the three groups. In T2DM patients, there was an increase in plasma insulin concentrations ten minutes after administration of 80 IU of intranasal insulin compared with saline.

CONCLUSIONS

In patients with and without T2DM undergoing elective cardiac surgery, intranasal insulin administration at doses as high as 80 IU did not cause clinically important hypoglycemia.

TRIAL REGISTRATION

www.ClinicalTrials.gov (NCT02729064); registered 5 April 2016.

Gastrodin alleviates perioperative neurocognitive dysfunction of aged mice by suppressing neuroinflammation

Perioperative neurocognitive disorder (PND) is a common complication of elderly patients after surgery and lacks effective prevention and treatment measures. We investigated the effect and mechanism of gastrodin (GAS), a natural plant ingredient, on postoperative cognition induced by laparotomy in aged mice. Male aged (18 months) mice were subjected to laparotomy and orally treated with GAS (25, 50, and 100 mg/kg) 3 weeks before surgery and 1 week after surgery. In addition, some male aged (18 months) mice were subjected to viral vector or GSK-3β expression virus injection followed by laparotomy with or without 100 mg/kg GAS treatment. GAS improved learning and memory in aged mice after surgery. Surgery increased the levels of pro-inflammatory factors (TNF-α, IL-1β and IL-6) and decreased the level of an anti-inflammatory factor (IL-10) in the mouse hippocampus, and these changes were reversed by GAS treatment. GAS also suppressed the activation of microglia. GAS inhibited the phosphorylation of GSK-3β and Tau. Furthermore, surgery induced more serious cognitive dysfunction, inflammatory factors, activation of microglia, and phosphorylation of GSK-3β and Tau in GSK-3β overexpressing aged mice. The improvement of learning and memory, the reduction of inflammation and microglia activation, and the suppression of GSK-3β and Tau phosphorylation by GAS were prevented when GSK-3β was overexpressed in aged mice subjected to surgery. Our finding suggested that GAS exerts neuroprotective effects in aged mice subjected to laparotomy by suppressing neuroinflammation and GSK-3β and Tau phosphorylation. Thus, these findings suggest that GAS may be a promising agent for PND.

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.

Cerebrospinal fluid cholinergic biomarkers are associated with postoperative delirium in elderly patients undergoing Total hip/knee replacement: a prospective cohort study

Background

Postoperative delirium (POD) is a frequent complication after surgery and its occurrence is associated with poor outcomes. The neuropathology of this complication is unclear, but it is important to evaluate relevant biomarkers for postoperative status. The purpose of this study is to explore the relationship between expression levels of cholinergic biomarkers in cerebrospinal fluid (CSF) and the occurrence and development of POD in elderly patients.

Methods

Four hundred and ninety-two elderly patients aged 65 years old or older with elective total hip/knee replacement received combined spinal-epidural anesthesia. Preoperative baseline cognitive function was assessed using the Mini-Mental State Examination (MMSE) before surgery. Each patient was interviewed in post-anesthesia care unit (PACU) and on the first, second, third and seventh (or before discharge) postoperative days. POD was diagnosed using the Confusion Assessment Method (CAM), and POD severity was measured using the Memorial Delirium Assessment Scale (MDAS). Preoperative CSF and plasma choline acetyltransferase (ChAT), acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels were determined by ELISA. The levels of ChAT, AChE and BuChE activities were determined by spectrophotometry.

Results

POD was detected in 11.4% (51/447) of the patients. AChE, BuChE, ChAT, TNF-α and IL-6 concentrations in CSF and plasma have higher consistency. In preoperative CSF and preoperative and postoperative plasma, down-regulation of the concentration and activity of AChE and BuChE as well as up-regulation of the concentration and activity of ChAT and the concentrations of IL-6 and TNF-α were observed in patients who developed POD, and the decrease in BuChE was the most obvious. Logistic analysis showed the activities of ChAT, AChE and BuChE in CSF were still related to POD after adjusting for related factors such as sex, age, years of education, height, weight, body mass index (BMI), and American Society of Anesthesiologists (ASA) class. Receiver Operating Characteristic (ROC) curve analysis was conducted to determine the Area Under Curve (AUC) of AChE, BuChE and ChAT activity in CSF was 0.679 (P < 0.01), 0.940 (P < 0.01) and 0.819 (P < 0.01) respectively and found that BuChE activity had the most accurate diagnostic value.

Conclusion

The changes in preoperative activity of AChE, BuChE and ChAT in CSF were associated with the development of POD in elderly patients, and BuChE activity had the greatest diagnostic value, which may be related to central cholinergic degradation. These cholinergic biomarkers might participate in the neuropathology of POD, pending further investigations.

Trial registration

This study was registered at Chictr.org.cn (NO. ChiCTR1900023729) June 9th, 2019. (Retrospectively registered).

Relationship between Surgery under General Anesthesia and the Development of Dementia: A Systematic Review and Meta-Analysis

Objective

To investigate the association between exposure to general anesthesia and the development of Alzheimer's disease (AD) and dementia by reviewing and integrating the evidence from epidemiological studies published to date.

Methods

We searched MEDLINE, EMBASE, and Google Scholar to identify all relevant articles up to April 2018 reporting the risk of AD/dementia following exposure to general anesthesia and finally updated in February 2020. We included patients older than 60 or 65 years who had not been diagnosed with dementia or AD before the study period. The overall pooled effect size (ES) was evaluated with a random-effect model. Subgroup analyses were conducted and possibility of publication bias was assessed.

Results

A total of 23 studies with 412253 patients were included in our analysis. A statistically significant positive association between exposure to general anesthesia and the occurrence of AD was detected in the overall analysis (pooled ES = 1.11, 95%confidence interval = 1.07–1.15), but with substantial heterogeneity (p_χ² < 0.001, I² = 79.4). Although the overall analysis revealed a significant association, the results of the subgroup analyses were inconsistent, and the possibility of publication bias was detected.

Conclusion

s. This meta-analysis demonstrated a significant positive association between general anesthesia and AD. However, considering other results, our meta-analysis must be interpreted with caution. Particularly, it should be considered that it was nearly impossible to discriminate the influence of general anesthesia from the effect of surgery itself on the development of AD. Further, large-scale studies devised to reduce the risk of bias are needed to elucidate the evidence of association between general anesthesia and AD. Trial registration. PROSPERO International prospective register of systematic reviews CRD42017073790.

Fracture shortly before stroke in mice leads to hippocampus inflammation and long-lasting memory dysfunction

Cognitive impairment occurs in stroke and hip fracture patients. In mice, bone fracture (BF) exacerbates stroke-related neuronal damage and sensorimotor dysfunction. We hypothesize that BF exacerbates post-stroke cognitive impairment. Adult mice were randomly assigned into BF, stroke, BF+stroke (BF 6 h before stroke), and control (sham operated) groups. Memory function was evaluated weekly for eight weeks by Y maze test and at eight weeks post-surgeries by novel object recognition (NOR) test. The neuronal damage and inflammation in hippocampus were analyzed three days and eight weeks after the surgeries. In Y maze test, BF+stroke mice started making fewer alternations than controls two weeks after the surgeries. Significant difference between BF+stroke and stroke groups started at five weeks post-injury and continued to the end of the experiment. In NOR test, BF+stroke group spent less time on novel objective than that of other groups. Cx3cr1⁺ cells and CD68⁺ cells accumulated in the stratum lacunosum moleculare (SLM) on the ipsilateral side of stroke injury in stroke and BF+stroke mice. BF+stroke mice had a higher ratio of ipsilateral/contralateral Cx3cr1⁺ cell-density than that of stroke mice. Therefore, BF shortly before stroke exacerbates hippocampal inflammation and causes long-lasting memory dysfunction.

Does Neuraxial Anesthesia as General Anesthesia Damage DNA? A Pilot Study in Patients Undergoing Orthopedic Traumatological Surgery

The human organism is exposed daily to many endogenous and exogenous substances that are the source of oxidative damage. Oxidative damage is one of the most frequent types of cell component damage, leading to oxidation of lipids, proteins, and the DNA molecule. The predominance of these damaging processes may later be responsible for human diseases such as cancer, neurodegenerative disease, or heart failure. Anesthetics undoubtedly belong to the group of substances harming DNA integrity. The goal of this pilot study is to evaluate the range of DNA damage by general and neuraxial spinal anesthesia in two groups of patients undergoing orthopedic traumatological surgery. Each group contained 20 patients, and blood samples were collected before and after anesthesia; the degree of DNA damage was evaluated by the comet assay method. Our results suggest that general anesthesia can cause statistically significant damage to the DNA of patients, whereas neuraxial anesthesia has no negative influence.

Insulin Resistance Predicts Postoperative Cognitive Dysfunction in Elderly Gastrointestinal Patients

Background

Members of the aging population who undergo surgery are at risk of postoperative cognitive dysfunction (POCD). Exploring an effective and reliable early predictor of POCD is essential to the identification of high-risk patients and to making prospective decisions. The purpose of this study was to examine whether preoperative insulin resistance is an independent predictor of POCD.

Methods

A total of 124 patients aged 60 years and older and who were scheduled for gastrointestinal surgery were enrolled in a prospective observational clinical study. All participants completed a battery of neuropsychological tests before surgery and 7 days later. POCD was defined as a decline of at least 1.5 SD on two or more of neuropsychological tests. Plasma concentration of the tumor necrosis factor α (TNF-α), C-reactive protein (CRP), and S-100β protein were measured. The status of insulin resistance was assessed by Homeostasis Model Assessment–Insulin Resistance (HOMA-IR). The relationship between HOMA-IR and POCD was assessed by Multivariable logistic regression models and the receiver operating characteristic (ROC) curve.

Results

Fifty one patients (41.1%) were diagnosed with POCD at 7 days after surgery. Preoperative HOMA-IR values of the POCD group were significantly higher than the non-POCD group. Furthermore, CRP and TNF-α levels of the POCD group were significantly higher at each postoperative time point (P < 0.05). The preoperative HOMA-IR value was an independent predictor of POCD (adjusted OR 1.88, 95% CI, 1.18–2.99) even after adjust for confounding variables, and when dichotomized, individuals above the HOMA-IR threshold (HOMA-IR > 2.6) had a three-times higher risk of POCD (OR 3.26; 95% CI, 1.07–9.91) compared to individuals below the threshold. The areas under the ROC curve of HOMA-IR was 0.804 (95% CI, 0.725–0.883; P < 0.001). The optimal cut-off value was found to be 0.583, with a sensitivity of 84.3% and specificity of 74%. The HOMA-IR value was positively associated with the TNF-α concentration at baseline (R² = 0.43, P < 0.01) and 1 day after surgery (R² = 0.3861, P < 0.01).

Conclusion

Preoperative insulin resistance is an effective predictor for the occurrence of POCD. Targeted prevention and treatment strategies of insulin resistance may be effective interventions of patients at risk for POCD.

AMPKα1 overexpression improves postoperative cognitive dysfunction in aged rats through AMPK-Sirt1 and autophagy signaling

Postoperative cognitive dysfunction (POCD) is a common complication in elderly patients who undergo surgery involving anesthesia. Its underlying mechanisms remain unclear. Autophagy plays an important role in the damage and repair of the nervous system and is associated with the development of POCD. Using a rat model, adenosine monophosphate-activated protein kinase α1 (AMPKα1), an important autophagy regulator, was found to be significantly downregulated in rats with POCD that was induced by sevoflurane anesthesia or by appendectomy. Overexpression of AMPKα1-ameliorated POCD, as indicated by decreased escape latencies and increased target quadrant swimming times, swimming distances, and platform crossing times during Morris water maze tests. AMPKα1 overexpression activated autophagy signals by increasing the expression of light chain 3 II (LC3-II) and Beclin1 and decreasing the expression of p62 in the hippocampus of rats with POCD. Moreover, blocking autophagy by 3-methyladenine partly attenuated AMPKα1-mediated POCD improvement. Furthermore, overexpression of AMPKα1 could upregulate the expression of p-AMPK and Sirt1 in the hippocampus of rats with POCD. Intriguingly, inhibiting AMPK signals via Compound C effectively attenuated AMPKα1-mediated POCD improvement, concomitant with the downregulation of p-AMPK, Sirt1, LC3-II, and Beclin1 and the upregulation of p62. We thus concluded that overexpression of AMPKα1 can improve POCD via the AMPK-Sirt1 and autophagy signaling pathway.

Transcriptomic analysis reveals the molecular mechanism of Alzheimer-related neuropathology induced by sevoflurane in mice

Anesthetics could induce cognitive dysfunctions, such as Alzheimer's disease in humans or mice. However, the precise molecular mechanism is unclear. Sevoflurane is a common anesthetic widely used in clinical practice. Here, we demonstrated the induction of cognitive dysfunction induced by Sev in mice to corroborate the signaling pathway and the differentially expressed genes (DEGs) followed by analyzing their functions. The cognitive function of mice was measured by the Morris water maze test. Transcriptomic data were annotated with Illumina HiSeq. 2000. Further, the changes in related proteins or genes were analyzed by western blotting and real-time quantitative polymerase chain reaction. Our results showed that Sev could cause a decline in cognitive competence in mice. The transcriptomic data indicated that adding up to 566 genes were upregulated and 1073 genes were downregulated. The genes of Plin4, Lcn2, Lrg1, Foxf1, and Ctla2a were significantly upregulated, while the genes of Arc, Npas4, Egr2, Hes5, and Cdh9 were downregulated dramatically. The Gene Ontology term with the highest enrichment of DEGs are involved in the regulation of cellular and macromolecule metabolism and cation and nucleic acid binding, respectively. The Kyoto encyclopedia of genes and genomes analysis indicated that the mitogen-activated protein kinases (MAPK) pathway was one of the most important metabolic pathways. In addition, the metabolic pathways related to cognitive function, such as the nervous system and neurodegenerative disease showed significant changes. Furthermore, we found that p38, c-Jun N-terminal kinase, and extracellular signal-regulated kinase of the MAPK signaling pathway played important roles in this process. In conclusion, these results provide the first important clues for identifying the DEGs and signaling pathways in the hippocampus due to a Sev-induced cognitive deficiency in mice.

The Trendelenburg Position and Cognitive Decline: A Case-Control Interventional Study Involving Healthy Volunteers

Background

Postoperative cognitive decline (POCD) is defined as a new cognitive impairment arising after a surgical intervention. Aspects of cognitive function can be assessed using various validated cognitive function tests including the N-back task, the Stroop task, and the lexical decision-making task (LDT). There is some concern that prolonged Trendelenburg positioning during laparoscopic colorectal surgery may cause POCD.

Objective

The objective of this study was to assess the effect of time spent in the Trendelenburg position on cognitive function.

Methods

Volunteers were placed in the Trendelenburg position for 3 hours and, then, supine for 30 minutes. Validated cognitive function tests including 1-, 2-, and 3-back tasks, Stroop test, and LDT were performed at baseline and every 30 minutes after Trendelenburg positioning. Cognitive decline was defined per the International Study of Postoperative Cognitive Dysfunction trial: a decrease in accuracy from the volunteers’ baseline or an increase in response time from the volunteers’ baseline by >2 control group SDs.

Results

We recruited 15 healthy volunteers (8 males, 7 females) with an average age of 69 years (range 57-81) and average body mass index of 27.7 kg/m² (range 20.9-33). Accuracy remained within 2 SDs at all time points. An increase in response time did occur, and of 15 participants, 3 (20%) showed cognitive decline in the Trendelenburg position after 30 minutes, 4 (27%) after 1 hour, 5 (33%) after 90 minutes, 4 (27%) after 120 and 150 minutes, and 6 (40%) after 180 minutes. On moving to a supine position, 33% (5/15) participants showed cognitive decline.

Conclusions

The results of this study indicate that Trendelenburg positioning leads to cognitive decline. This may have implications for patients undergoing prolonged Trendelenburg positioning during laparoscopic colorectal surgery.

Microarray Expression Profiles of lncRNAs and mRNAs in Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) is serious disorder in the central nervous system common in aged patients after anesthesia. Although its clinical symptoms are well recognized, however, the molecular etiology of the POCD remains unrevealed. Similarly, neither gold standard molecular diagnosis nor effective treatment is available for POCD until the present. Therefore, we aimed to explore the molecular mechanism of this disorder through investigating lncRNAs and mRNAs associated with POCD human patients and investigate their underlying regulatory pathways. In this study, we recruited 200 patients requiring hip or knee replacement surgery. Their neurological functions were assessed at two time points, 1 day before the surgery and 30 days post-surgery. In parallel, serum samples were collected from the participants to analyze lncRNAs and mRNAs differential expression profile between POCD and non-POCD patients using microarray analysis. To further investigate the role differentially expressed mRNA and lncRNAs, Gene Ontology (GO), pathway analyses on mRNAs and lncRNA-mRNA interaction network were performed. As a result, 68 lncRNAs and 115 mRNAs were dysregulated in the POCD group compared to non-POCD group. Among them, the top 10 upregulated lncRNAs and 10 downregulated lncRNAs were listed for enrichment analysis. Interestingly, we found that these lncRNA and mRNA are involved in biological process, molecular function, and cellular component in addition to various signaling pathways, suggesting that the pathogenesis of POCD involves lncRNAs and mRNAs differential expression. Consequently, the genetic dysregulation between the non-POCD and POCD patients participates in the occurrence and development of POCD, and could be served as diagnostic biomarkers and drug targets for POCD treatment.

Impact of Bone Fracture on Ischemic Stroke Recovery

Stroke is one of the most devastating complications of bone fracture, occurring in up to 4% of patients after surgical repair for hip fracture. Bone fracture and ischemic stroke have many common risk factors. The impact of bone fracture on stroke recovery has not drawn much attention in the research field. Bone fracture could occur in stroke patients at different times during the recovery phase, which steepens the trajectory of cognitive decline, greatly affects the quality of life, and causes a heavy burden on healthcare resources. In this paper, we reviewed the growing information on the pathophysiological mechanisms by which bone fracture may affect ischemic stroke recovery process.

Clinical outcomes in older surgical patients with mild cognitive impairment

INTRODUCTION

Older adults, including those with mild cognitive impairment (MCI), are increasingly undergoing surgery.

METHODS

Relative risks (RRs) of MCI alone or with delirium on adverse outcomes were estimated in an ongoing prospective, observational cohort study of 560 nondemented adults aged ≥70 years.

RESULTS

MCI (n = 61, 11%) was associated with increased RR of delirium (RR = 1.9, P < .001) and delirium severity (RR = 4.6, P < .001). Delirium alone (n = 107), but not MCI alone (n = 34), was associated with multiple adverse outcomes including more major postoperative complication(s) (RR = 2.5, P = .002) and longer length of stay (RR = 2.2, P < .001). Patients with concurrent MCI and delirium (n = 27) were more often discharged to a postacute facility (RR = 1.4, P < .001) and had synergistically increased risk for new impairments in cognitive functioning (RR = 3.6, P < .001).

DISCUSSION

MCI is associated with increased risk of delirium incidence and severity. Patients with delirium and MCI have synergistically elevated risk of developing new difficulties in cognitively demanding tasks.

Repeat propofol anesthesia does not exacerbate plaque deposition or synapse loss in APP/PS1 Alzheimer's disease mice

Background

There is increasing interest in whether anesthetic agents affect the risk or progression of Alzheimer’s disease (AD). To mitigate many of the methodological issues encountered in human retrospective cohort studies we have used a transgenic model of AD to investigate the effect of propofol on AD pathology.

Methods

Six month-old amyloid precursor protein/presenilin 1 (APP/PS1) transgenic AD mice and control mice were exposed to 3 doses of propofol (200 mg/kg) or vehicle, delivered at monthly intervals.

Results

There was no difference in the extent of β-amyloid (Aβ) immunolabeled plaque deposition in APP/PS1 mice in vehicle versus propofol treatment groups. We also detected no difference in plaque-associated synapse loss in APP/PS1 mice following repeat propofol exposure relative to vehicle. Western blotting indicated that there was no difference in post-synaptic density protein 95, synaptophysin or glutamic acid decarboxylase 65/67 expression in control or APP/PS1 mice subjected to repeat propofol treatment relative to vehicle.

Conclusions

These data suggest that repeat propofol anesthesia may not exacerbate plaque deposition or associated synapse loss in AD. Interestingly, this data also provides some of the first evidence suggesting that repeat propofol exposure in adult wild-type mice does not result in robust long-term alterations in the levels of key excitatory and inhibitory synaptic markers.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0509-5) contains supplementary material, which is available to authorized users.

Pretreatment with nimodipine reduces incidence of POCD by decreasing calcineurin mediated hippocampal neuroapoptosis in aged rats

Background

Calcineurin (CaN) having a high expression in hippocampal neurons is closely related to apoptosis. Pretreatment with nimodipine can lower the apoptosis rate of hippocampal neuron to reduce the incidence of postoperative cognitive dysfunction (POCD). However, the relationship between cerebral protective effect of pretreatment with nimodipine and CaN is controversial in the literature. The aim of this study is to evaluate the relationship between neuroprotective effect of nimodipine and CaN on POCD in aged rats.

Methods

Ninety-six 18-month-old male Sprague-Dawley rats were randomly assigned into 4 groups (n = 24 each): control group (Group C), nimodipine group (Group N), surgery group (Group S) and nimodipine + surgery group (Group N + S). In Group N and Group N + S, nimodipine 1 mg/kg was intraperitoneally injected, while the equal volume of normal saline was given instead in Group S. 30 min later, Group N and Group C inhaled pure oxygen for 2 h, and Group S and N + S inhaled 3% sevoflurane for 2 h when exploratory laparotomy was performed. Morris water maze test was performed on 1 day before operation and 1, 3 and 7 days after operation. After the end of Morris water maze test at 1 day before operation and 1 and 7 days after operation, 8 rats were sacrificed, brains were removed and hippocampal tissues were obtained for detection of apoptosis in hippocampal neurons, cytoplasmic calcium ([Ca²⁺]_i), and hippocampal CaN and caspase-3 expression.

Results

Compared with the 1st day before operation, the escape latency, apoptosis rate, [Ca²⁺]_i, expression of CaN and caspase-3 increased significantly, but the frequency of crossing the original platform decreased dramatically in Group S and N + S(P<0.05). In addition, the escape latency, apoptosis rate, [Ca²⁺]_i, and expression of CaN and caspase-3 decreased markedly, but the frequency of crossing the original platform increased significantly in Group N + S as compared with Group S (P<0.05).

Conclusions

Pretreatment with nimodipine reduces the incidence of POCD by decreasing CaN mediated hippocampal neuroapoptosis in aged rats.

Inhalational Anesthetics Induce Neuronal Protein Aggregation and Affect ER Trafficking

Anesthetic agents have been implicated in the causation of neurological and cognitive deficits after surgery, the exacerbation of chronic neurodegenerative disease, and were recently reported to promote the onset of the neurologic respiratory disease Congenital Central Hypoventilation Syndrome (CCHS), related to misfolding of the transcription factor Phox2B. To study how anesthetic agents could affect neuronal function through alterations to protein folding, we created neuronal cell models emulating the graded disease severity of CCHS. We found that the gas anesthetic isoflurane and the opiate morphine potentiated aggregation and mislocalization of Phox2B variants, similar to that seen in CCHS, and observed transcript and protein level changes consistent with activation of the endoplasmic reticulum (ER) unfolded protein response. Attenuation of ER stress pathways did not result in a correction of Phox2B misfolding, indicating a primary effect of isoflurane on protein structure. We also observed that isoflurane hindered the folding and activity of proteins that rely heavily on ER function, like the CFTR channel. Our results show how anesthetic drugs can alter protein folding and induce ER stress, indicating a mechanism by which these agents may affect neuronal function after surgery.

High doses of minocycline may induce delayed activation of microglia in aged rats and thus cannot prevent postoperative cognitive dysfunction

Objective

Postoperative cognitive dysfunction (POCD) is common after surgery in elderly patients and is associated with high morbidity. The molecular mechanisms responsible for POCD are unknown. Minocycline, an inhibitor of microglial activation, may be useful in treating and preventing POCD. We explored whether minocycline can inhibit microglial activation and prevent POCD in aged rats as a surgery model.

Methods

Rats aged 18 to 20 months were randomly allocated to the following groups: naïve, abdominal surgery alone, or minocycline injection before abdominal surgery. Hippocampal cytokine mRNA levels were measured at 3 hours, 1 day, 3 days, and 7 days after surgery, and microglial activation was measured at 3 hours and 7 days after surgery. Memory was assessed using the Morris water maze test.

Results

Surgery resulted in severe cognitive impairment in aged rats and induced a significant neuroinflammatory response and microglial activation. The use of minocycline can prevent microglial activation after surgery, but delayed microglial activation may occur. The use of minocycline may further impair memory after surgery.

Conclusion

Minocycline can restrain microglial activation and restrict the inflammatory response in the hippocampus early after surgery, but it may induce delayed microglial activation and cannot prevent POCD in aged rats.

Screening of Potential Genes and Transcription Factors of Postoperative Cognitive Dysfunction via Bioinformatics Methods

Background

The aim of this study was to explore the potential genes and transcription factors involved in postoperative cognitive dysfunction (POCD) via bioinformatics analysis.

Material/Methods

GSE95070 miRNA expression profiles were downloaded from Gene Expression Omnibus database, which included five hippocampal tissues from POCD mice and controls. Moreover, the differentially expressed miRNAs (DEMs) between the two groups were identified. In addition, the target genes of DEMs were predicted using Targetscan 7.1, followed by protein-protein interaction (PPI) network construction, functional enrichment analysis, pathway analysis, and prediction of transcription factors (TFs) targeting the potential targets.

Results

A total of eight DEMs were obtained, and 823 target genes were predicted, including 170 POCD-associated genes. Furthermore, potential key genes in the network were remarkably enriched in focal adhesion, protein digestion and absorption, ECM-receptor interaction, and Wnt and MAPK signaling pathways.

Conclusions

Most potential target genes were involved in the regulation of TFs, including LEF1, SP1, and AP4, which may exert strong impact on the development of POCD.

Isoflurane anesthesia in aged mice and effects of A1 adenosine receptors on cognitive impairment

AIMS

Isoflurane may not only accelerate the process of Alzheimer's disease (AD), but increase the risk of incidence of postoperative cognitive dysfunction (POCD). However, the underlying mechanisms remain unknown. This study was designed to investigate whether isoflurane contributed to the POCD occurrence through A1 adenosine receptor (A1AR) in aged mice.

METHODS

We assessed cognitive function of mice with Morris water maze (MWM) and then measured expression level of two AD biomarkers (P-tau and Aβ) and a subtype of the NMDA receptor (NR2B) in aged wild-type (WT) and homozygous A1 adenosine receptor (A1AR) knockout (KO) mice at baseline and after they were exposed to isoflurane (1.4% for 2 hours).

RESULTS

For cognitive test, WT mice with isoflurane exposure performed worse than the WT mice without isoflurane exposure. However, A1AR KO mice with isoflurane exposure performed better than WT mice with isoflurane exposure. WT mice exposed to isoflurane had increased levels of Aβ and phosphorylated tau (P-tau). Levels of Aβ and P-tau were decreased in A1AR KO mice, whereas no differences were noted between KO mice with and without isoflurane exposure. NR2B expression was inversely related to that of P-tau, with no differences found between KO mice with and without isoflurane exposure.

CONCLUSIONS

We found an association between isoflurane exposure, impairment of spatial memory, decreasing level of NR2B, and increasing levels of A-beta and P-tau, presumably via the activation of the A1A receptor.

Erythropoietin Attenuates Postoperative Cognitive Dysfunction by Shifting Macrophage Activation toward the M2 Phenotype

Postoperative cognitive dysfunction (POCD) may be driven by transference of the innate immune response to the brain after aseptic surgical damage. Macrophages are key mediators of innate immunity that can display a pro-inflammatory M1 phenotype or an anti-inflammatory M2 phenotype. Erythropoietin (EPO) is a hematopoietic hormone that exerts anti-inflammatory effects by influencing macrophage function. We hypothesized that EPO would prevent POCD by promoting macrophage phenotype switching to the M2 phenotype post-surgery. To evaluate the effects of EPO on POCD and macrophage polarization post-surgery, we administered EPO (5,000 U/kg) with or without an arginase inhibitor (amino-6-boronohexanoic acid, 10 mg/kg) to ICR mice before and after abdominal surgery. Forty-eight hours post-surgery, we assessed memory, synapse function, and macrophage/microglial phenotypes in the spleen and hippocampus. We also investigated M1/M2 phenotypes in RAW264.7 and BV2 cells stimulated with lipopolysaccharide and interferon-γ (M1 inducers) in the presence or absence of EPO. EPO prevented POCD, decreased surgery-related synaptic dysfunction, and attenuated pro-inflammatory cytokine generation in the hippocampus. Moreover, EPO suppressed M1-related genes expression and promoted M2 genes expression in the spleen and hippocampus post-surgery. Furthermore, EPO decreased the proportions of macrophages/microglia expressing an M1 surface marker (CD40) and increased those expressing an M2 surface marker (CD206). Arginase inhibition abolished the beneficial effects of EPO on POCD. In vitro, EPO treatment promoted switching of RAW264.7 and BV2 cells stimulated with M1 inducers to an M2 phenotype. In conclusion, EPO prevents POCD by promoting macrophage phenotype switching toward the M2 phenotype.

Effects of andrographolide on postoperative cognitive dysfunction and the association with NF-κB/MAPK pathway

The present study investigated the effects of andrographolide on postoperative cognitive dysfunction (POCD) in aged rats to gain insight of the underlying mechanism, which may provide theoretical basis for the clinical application of andrographolide to prevent POCD in older patients. Thirty aged male rats were randomly assigned to 3 groups: Control, model and andrographolide groups. The Morris water maze test was used to examine the spatial memory and learning ability of the rats postoperatively. The histological alterations of neuronal cells in the hippocampus were visualized by H&E staining. The serum levels of neuron-specific enolase (NSE), human soluble protein-100β (S-100β) and the inflammation factors of interluekin (IL)-1β, IL-6 and TNF-α involved in the nuclear factor κB (NF-κB)/mitogen-activated protein kinase (MAPK) signaling pathway were detected by ELISA. The NF-κB/MAPK signaling pathway-associated proteins in rat serum were detected by western blotting. Following andrographolide treatment, the rats significantly gained learning ability after surgery. Is it ameliorated hippocampal neuronal injury in rats following surgery. Andrographolide decreased NSE, S-100β, and the inflammation factors, IL-6, IL-1β and TNF-α in serum. Andrographolide reduced NF-κB/MAPK pathway-associated protein expression. Andrographolide ameliorated POCD in aged rats following surgery. The underlying mechanism may be associated with the downregulation the inflammatory factors and NF-κB/MAPK-associated protein expression.

Protective effects of parecoxib on rat primary astrocytes from oxidative stress induced by hydrogen peroxide

OBJECTIVE

To investigate the protective effects of parecoxib from oxidative stress induced by hydrogen peroxide (H2O2) in rat astrocytes in vitro.

METHODS

All experiments included 4 groups: (1) negative control (NC) group, without any treatment; (2) H2O2 treatment group, 100 μmol/L H2O2 treatment for 24 h; (3) and (4) parecoxib pretreatment groups, 80 and 160 μmol/L parecoxib treatment for 24 h, respectively, and then treated with 100 μmol/L H2O2. Several indices were investigated, and the expressions of Bax, Bcl-2, and brain-derived neurotrophic factor (BDNF) were quantified.

RESULTS

Compared to the NC group, exposure to H2O2 resulted in significant morphological changes, which could be reversed by pretreatment of parecoxib. In addition, H2O2 treatment led to loss of viability (P=0.026) and increased intracellular reactive oxygen species (ROS) levels (P<0.001), and induced apoptosis (P<0.01) in the primary astrocytes relative to the NC group. However, in the parecoxib pretreatment groups, all the above changes reversed significantly (P<0.05) as compared to the H2O2 treatment group, and were nearly unchanged when compared to the NC group. Mechanical investigation showed that dysregulated Bax, Bcl-2, and BDNF could be implicated in these changes.

CONCLUSIONS

Our results indicated that parecoxib provided a protective effect from oxidative stress induced by exposure to H2O2.

Effects of preconditioning of electro-acupuncture on postoperative cognitive dysfunction in elderly: A prospective, randomized, controlled trial

Electro-acupuncture is a burgeoning treatment using the needle inserting into the body acupoints and the low-frequency pulse current being electrified by an electric acupuncture machine. This study was designed to evaluate the effects of preconditioning of electro-acupuncture on postoperative cognitive dysfunction in elderly.Ninety patients scheduled spine surgery were randomly assigned into 2 groups using a random number table: control group (group C) and electro-acupuncture group (group EA). In group EA, electro-acupuncture was applied on Baihui, Dazhui, and Zusanli acupoints 30 minutes before anesthesia. At 0 minute before treatment of electro-acupuncture, 1 hour after skin incision and surgery completed (T1-3), blood samples were taken for detection of interleukin (IL)-6, IL-10, and S100β by enzyme-linked immunosorbent assay. The total dose of remifentanil and propofol during surgery were recorded. Mini-Mental State Examination was applied to evaluate the cognitive function of patients at 1 day before surgery and 7th and 30th day after surgery.The results showed that compared with group C, score of MMSE increased after surgery, the serum concentration of IL-6, IL-10, and S100β decreased at 1 hour after skin incision, and surgery completed in group EA. Moreover, the total dose of remifentanil and propofol reduced during surgery in group EA.The present study suggests that preconditioning of electro-acupuncture could improve the postoperative cognitive function, and the reduction of inflammatory reaction and brain injury may be involved in the mechanism.

Preoperative Serum MicroRNA-155 Expression Independently Predicts Postoperative Cognitive Dysfunction After Laparoscopic Surgery for Colon Cancer

Background

The aim of this study was to examine the association between serum expression of miRNA-155 and postoperative cognitive dysfunction (POCD) after laparoscopic surgery for colon cancer.

Material/Methods

We enrolled 110 patients scheduled to undergo colon tumor resection via laparotomy in Ningbo No. 2 Hospital from July 2013 to November 2015. The blood samples were collected from the participants 1 day before surgery. Multiple logistic regression analysis was used for the analysis of independent predictive biomarkers for POCD.

Results

On the 7^th postoperative day, 29 of the 110 participants developed POCD, yielding a POCD incidence of 26.4%. Age, MMSE score, duration of surgery and anesthesia, serum levels of CRP, TNF-α, urea, creatinine, and miRNA-155 were highly associated with the occurrence of POCD. Serum expression of miRNA-155 was shown by multiple logistic regression analysis to be an independent predictive indicator for POCD after surgery (OR: 2.732; 95%CI 1.415–5.233; P=0.002).

Conclusions

The serum expression of miRNA-155 is an independent predictive factor for POCD after laparoscopic surgery for colon cancer.