Dusp4 Contributes to Anesthesia Neurotoxicity via Mediated Neural Differentiation in Primates

Role of Hippocampal Glutamatergic Synaptic Alterations in Sevoflurane-Induced Cognitive Dysfunction in Aged Mice

AIMS

Perioperative neurocognitive disorders (PND), including postoperative delirium (POD) and postoperative cognitive dysfunction (POCD), are common following anesthesia and surgery in older patients and significantly increase morbidity and mortality. However, the underlying mechanism of PND is unclear. Our study aims to analyze the differentially expressed genes (DEGs) in excitatory neurons and investigate the role of hippocampal glutamatergic synaptic alterations in sevoflurane-induced cognitive dysfunction in aged mice.

METHODS

We performed single-nucleus RNA sequencing (snRNA-seq) technology to examine the alterations of excitatory neurons in hippocampus induced by sevoflurane in aged mice. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of DEGs were performed in excitatory neurons. At last, immunofluorescence staining was used to validate sevoflurane-induced alternation of glutamatergic synapses in the hippocampus of aged mice.

RESULTS

This study demonstrates that DEGs in excitatory neurons are associated with reduction of glutamatergic synapses and cognitive dysfunction. After immunofluorescence staining validation, we also confirmed that sevoflurane anesthesia decreased the density of glutamatergic synapses in the hippocampus of aged mice.

CONCLUSIONS

Our findings demonstrated a key role of hippocampal glutamatergic synaptic alterations in sevoflurane-induced cognitive dysfunction in aged mice.

Risk of attention deficit hyperactivity disorder diagnosis following multiple exposures to general anesthesia in the paediatric population: A systematic review and meta-analysis

Objectives

The risk of attention deficit hyperactivity disorder (ADHD) following multiple exposures to anesthesia has been debated. Our objective was to systematically review the literature to examine the association between multiple exposures to general anesthesia before age 5 and subsequent diagnosis of ADHD.

Methods

A systematic search of EMBASE, PubMed, and SCOPUS was performed using key search terms in February 2022. We included studies that: were published after 1980, included only otherwise healthy children who experienced two or more exposures to general anesthetic before age 5, diagnosed ADHD by a medical professional before age 19 years after exposure to general anesthetic, were cross-sectional, case-control, or cohort study, and were published in English. The results (expressed as hazard ratios [HR] and associated 95% confidence intervals [CI]) were pooled using meta-analytic techniques. Studies which did not present their results as HR and 95% CI were analyzed separately. GRADE was used to determine the certainty of the findings. PRISMA guidelines were followed at each stage of the review.

Results

Eight studies (196,749 children) were included. Five reported HR and 95% CI and were subsequently pooled for meta-analysis. Multiple exposures to anesthesia were associated with diagnosis of ADHD before the 19th year of life (HR: 1.71; 95% CI: 1.59, 1.84). Two of the three studies not used in the meta-analysis also found an increased risk of ADHD diagnosis following multiple anesthetic exposures.

Conclusions

There was an association between multiple early exposures to general anesthesia and later diagnosis of ADHD.

Inhibitory neuron map of sevoflurane induced neurotoxicity model in young primates

Introduction

Sevoflurane, one of the most commonly used anesthetic agents in children, may induce neuronal dysfunction and cognitive impairment. Exposure to sevoflurane might induce an imbalance between neural excitation and inhibition which could be a mechanism behind anesthesia-induced cognitive and affective dysfunctions. However, the underlying mechanisms remain unclear.

Methods

In this study, we used two rhesus macaques in the control group, and one rhesus macaques in the anesthesia group. We employed single-nucleus RNA sequencing (snRNA-seq) technology to explore alterations in distinct types of inhibitory neurons involved in the long-term cognitive impairment caused by sevoflurane in young macaques.

Results

Following sevoflurane treatment, an upregulation was observed in the SST+ inhibitory neuron in the LHX6+ neighborhood in the hippocampus of rhesus macaques. This alteration might impact brain development by influencing interneuron migration and maturation. Additionally, we proposed a novel classification of inhibitory neurons, defined by CNR1 and LHX6 applicable to both humans and macaques.

Discussion

Our study proposed a novel classification of inhibitory neurons defined by LHX6 and CNR1, relevant in macaques and humans. We also provide evidence that sevoflurane upregulated the SST+ inhibitory neuron in the LHX6+ neighborhood in the hippocampus of rhesus macaques, which may underlie the potential neurotoxic effects induced by general anesthetics. Our results also offer a more reliable approach for studying the structure and function of the human brain.

Anesthesia and developing brain: What have we learned from recent studies

Anesthesia is unavoidable in surgical procedures. However, whether the general anesthetics are neurotoxic to immature brains remains undefined. Neurodevelopmental impairment induced by anesthesia has been a critical health issue and topic of concern. This review summarizes recent progress made in clinical and preclinical studies to provide useful suggestions and potential therapeutic targets for the protection of the immature brain. On the one hand, clinical researchers continue the debate about the effect of single and multiple exposures to anesthesia on developing brains. On the other hand, preclinical researchers focus on exploring the mechanisms of neurotoxic effects of general anesthesia on immature brains and seeking novel solutions. Rodent models have always been used in preclinical studies, but it is still unclear whether the mechanisms observed in rodent models have clinical relevance. Compared with these models, non-human primates (NHPs) are more genetically similar to humans. However, few research institutions in this area can afford to use NHP models in their studies. One way to address both problems is by combining single-cell sequencing technologies to screen differential gene expression in NHPs and perform in vivo validation in rodents. The mechanism of anesthesia-induced neurotoxicity still requires further elucidation in primates.

Exposure to general anaesthesia in childhood and the subsequent risk of attention-deficit hyperactivity disorder: A meta-analysis of cohort studies

BACKGROUND

The evidence for a relationship between general anaesthesia induced in childhood and the risk of attention-deficit hyperactivity disorder (ADHD) in later life is inconsistent. We systematically assessed whether such an association existed.

METHODS

We searched the PubMed and EMBASE databases for relevant cohort studies. Relative risks (RRs) and 95 % confidence intervals (CIs) were calculated to determine the relationship between induction of childhood general anaesthesia and the risk of ADHD in later life.

RESULTS

Seven studies (eight publications) on developmental outcomes after the induction of childhood general anaesthesia met our inclusion criteria but not our exclusion criteria. Repeat childhood general anaesthesia (RR = 1.84, 95 CI% 1.14-2.97; P < 0.001; I² = 74.8 %), but not one-off general anaesthesia (RR = 1.09, 95 CI% 0.93-1.27; P = 0.301; I² = 0%), was associated with an increased risk of ADHD in later life. The association was evident only when the total general anaesthesia exposure exceeded 90 min.

CONCLUSIONS

Our meta-analysis indicated that the effect of general anaesthesia on the risk of ADHD is dose- or duration-dependent.

Brain transcriptomics of nonhuman primates: A review

The brain is one of the most important and intricate organs in our bodies. Interpreting brain function and illustrating the changes and molecular mechanisms during physiological or pathological processes are essential but sometimes difficult to achieve. In addition to histology, ethology and pharmacology, the development of transcriptomics alleviates this condition by enabling high-throughput observation of the brain at various levels of anatomical specificity. Moreover, because human brain samples are scarce, the brains of nonhuman primates are important alternative models. Here in this review, we summarize the applications of transcriptomics in nonhuman primate brain studies, including investigations of brain development, aging, toxic effects and diseases. Overall, as a powerful tool with developmental potential, transcriptomics has been widely utilized in neuroscience.