Research progress and treatment strategies for anesthetic neurotoxicity

Lithium attenuates ketamine-induced long-term neurotoxicity through DISC1-mediated GSK-3β/β-catenin and ERK/CREB pathways

Ketamine, an antagonist of N-methyl-D-aspartate receptor, is extensively employed in pediatric anesthesia. Multiple studies have shown that repeated ketamine exposure induces neuroapoptosis, synaptic changes and cognitive deficits during neurodevelopment. Therefore, it is essential to elucidate the mechanisms of ketamine-induced neurotoxicity and develop therapies to mitigate its harmful effects. Here, we investigated the role of disrupted in Schizophrenia 1 (DISC1) in ketamine-induced long-term neurotoxicity through a ketamine-exposed neuroapoptosis model. Neonatal rats received 2-5 intraperitoneal injections of ketamine (20 mg/kg b.w.) at 90 min intervals. Another cohort of pups received five intraperitoneal injections of ketamine (20 mg/kg×5 b.w.) with or without lithium (120 mg/kg×5 b.w.) at 90 min intervals over 6 h. Neuroapoptosis, DISC1-associated proteins expression in rats treated with ketamine, lithium, or a combination of both were detected, and the cognitive function of adolescent rats was evaluated by Morris water maze test. The length of dendrites and axons of primary neurons treated with lithium and ketamine were further measured. Results showed that ketamine time-dependently downregulated the levels of DISC1, pGSK-3β, β-catenin, pERK, pCREB and PSD95 in neonatal rats. Lithium could ameliorate neuroapoptosis, cognitive deficits and neurite growth inhibition triggered by ketamine. Mechanistically, lithium upregulated the levels of DISC1, PSD95 and GSK-3β/β-catenin and ERK/CREB signaling-related proteins. Consequently, lithium mitigated ketamine-induced long-term neurotoxicity by elevating DISC1 level and activating the GSK-3β/β-catenin and ERK/CREB signaling pathways.

A Scoping Review of the Mechanisms Underlying Developmental Anesthetic Neurotoxicity

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

The lateral septum partakes the regulation of propofol-induced anxiety-like behavior

Repeated exposure to propofol during early brain development is associated with anxiety disorders in adulthood, yet the mechanisms underlying propofol-induced susceptibility to anxiety disorders remain elusive. The lateral septum (LS), primarily composed of γ-aminobutyric acidergic (GABAergic) neurons, serves as a key brain region in the regulation of anxiety. However, it remains unclear whether LS GABAergic neurons are implicated in propofol-induced anxiety. Therefore, we conducted c-Fos immunostaining of whole-brain slices from mice exposed to propofol during early life. Our findings indicate that propofol exposure activates GABAergic neurons in the LS. Selective activation of LS GABAergic neurons resulted in increased anxiety-like behavior, while selective inhibition of these neurons reduced such behaviors. These results suggest that the LS is a critical brain region involved in propofol-induced anxiety. Furthermore, we investigated the molecular mechanism of propofol-induced anxiety in the LS. Microglia activation underlies the development of anxiety. Immunofluorescence staining and Western blot analysis of LS revealed activated microglia and significantly elevated levels of phospho-NF-κB p65 protein. Additionally, a decrease in the number of neuronal spines was observed. Our study highlights the crucial role of the LS in the development of anxiety-like behavior in adulthood following childhood propofol exposure, accompanied by the activation of inflammatory pathways.

Plasma neurological biomarkers as a measure of neurotoxicity in pediatric dental general anesthesia: a prospective observational feasibility study

PURPOSE

Neurotoxicity concerns have been raised over general anesthesia and sedation medication use in children. Such concerns are largely based on animal studies, historical anesthetic agents, and assessment tools, thus warranting further investigations. Blood biomarkers in detecting neuronal inflammation and apoptosis are novel methods for detecting neuronal damage. Therefore, the aim of this feasibility study was to assess the usefulness of the levels of four plasma biomarkers in dental general anesthesia (DGA) as surrogate markers of neurotoxicity in children. The secondary aim was to compare changes in motor manipulative skills pre- and post-anesthetic exposure.

METHODS

This single-center prospective observational study included 22 healthy children aged between 3 and 6 years old who underwent DGA. Subclinical neurotoxicity was measured with a panel of four plasma biomarkers: Caspase-3, neuron-specific enolase (NSE), neurofilament light chain, and S100B at three time points (1; at start, 2; end and 3; on recovery from DGA). The Skillings-Mack test was used to identify the difference in the biomarker levels at three time points. Motor manipulative score assessment, prior and two weeks after DGA was also performed.

RESULTS

A total of 22 study participants (mean age = 5 ± 1 years) were included with a median DGA duration of 106 ± 28 min. A reduction in Caspase-3 levels was recorded, with pairwise comparison over three time points, reporting a statistical significance between time point 2 vs. 1 and time point 3 vs. 1. Although fluctuations in NSE levels were recorded, no significant changes were found following pairwise comparison analysis. Among other biomarkers, no significant changes over the three periods were recorded. Furthermore, no significant changes in manipulative motor scores were reported.

CONCLUSION

Caspase-3 reduced significantly in the short time frames during day-care DGA; this might be due to the relatively short anesthesia duration associated with dental treatment as compared with more extensive medical-related treatments. Therefore, further studies on Caspase-3 as a potential biomarker in pediatric DGA neurotoxicity are required to further ascertain results of this study.

The effects of general anesthetics on mitochondrial structure and function in the developing brain

The use of general anesthetics in modern clinical practice is commonly regarded as safe for healthy individuals, but exposures at the extreme ends of the age spectrum have been linked to chronic cognitive impairments and persistent functional and structural alterations to the nervous system. The accumulation of evidence at both the epidemiological and experimental level prompted the addition of a warning label to inhaled anesthetics by the Food and Drug Administration cautioning their use in children under 3  years of age. Though the mechanism by which anesthetics may induce these detrimental changes remains to be fully elucidated, increasing evidence implicates mitochondria as a potential primary target of anesthetic damage, meditating many of the associated neurotoxic effects. Along with their commonly cited role in energy production via oxidative phosphorylation, mitochondria also play a central role in other critical cellular processes including calcium buffering, cell death pathways, and metabolite synthesis. In addition to meeting their immense energy demands, neurons are particularly dependent on the proper function and spatial organization of mitochondria to mediate specialized functions including neurotransmitter trafficking and release. Mitochondrial dependence is further highlighted in the developing brain, requiring spatiotemporally complex and metabolically expensive processes such as neurogenesis, synaptogenesis, and synaptic pruning, making the consequence of functional alterations potentially impactful. To this end, we explore and summarize the current mechanistic understanding of the effects of anesthetic exposure on mitochondria in the developing nervous system. We will specifically focus on the impact of anesthetic agents on mitochondrial dynamics, apoptosis, bioenergetics, stress pathways, and redox homeostasis. In addition, we will highlight critical knowledge gaps, pertinent challenges, and potential therapeutic targets warranting future exploration to guide mechanistic and outcomes research.

A bibliometric analysis of the neurotoxicity of anesthesia in the developing brain from 2002 to 2021

Background

The neurotoxicity effects of anesthetic exposure on the developing brain have been one of the current research hotspots and numerous articles were published in the past decades. However, the quality and comparative information of these articles have not been reported. This research aimed to provide a comprehensive overview of the current state of the field by investigating research hotspots and publication trends concerning the neurotoxicity of anesthesia in the developing brain.

Materials and methods

On 15 June 2022, we searched articles on the neurotoxicity of anesthesia in the developing brain through the Science Citation Index databases from 2002 to 2021. Data of the author, title, publication, funding agency, date of publication, abstract, type of literature, country, journal, keywords, number of citations, and research direction were collected for further analysis.

Results

We searched and analyzed 414 articles in English on the field of neurotoxicity of anesthesia in the developing brain from 2002 to 2021. The country with the largest number of publications was The United States (US) (n = 226), which also had the largest total number of citations (10,419). Research in this field reached a small peak in 2017. Furthermore, the largest number of articles were published in three journals, Anesthesiology, Anesthesia and Analgesia, and Pediatric Anesthesia. The top 20 articles that were cited most often were studied. In addition, the top hotspots of this area in clinical investigations and basic research were analyzed separately.

Conclusion

This study provided an overview of the development in the neurotoxicity of anesthesia in the developing brain using bibliometric analysis. Current clinical studies in this area were mainly retrospective; in the future, we should place more emphasis on prospective, multicenter, long-term monitoring clinical studies. More basic research was also needed on the mechanisms of neurotoxicity of anesthesia in the developing brain.

Effect of Anesthetics on Functional Connectivity of Developing Brain

The potential anesthetic neurotoxicity on the neonate is an important focus of research investigation in the field of pediatric anesthesiology. It is essential to understand how these anesthetics may affect the development and growth of neonatal immature and vulnerable brains. Functional magnetic resonance imaging (fMRI) has suggested that using anesthetics result in reduced functional connectivity may consider as core sequence for the neurotoxicity and neurodegenerative changes in the developed brain. Anesthetics either directly impact the primary structures and functions of the brain or indirectly alter the hemodynamic parameters that contribute to cerebral blood flow (CBF) in neonatal patients. We hypothesis that anesthetic agents may either decrease the brain functional connectivity in neonatal patients or animals, which was observed by fMRI. This review will summarize the effect and mechanism of anesthesia on the rapid growth and development infant and neonate brain with fMRI through functional connectivity. It is possible to provide the new mechanism of neuronal injury induced by anesthetics and objective imaging evidence in animal developing brain.

Neuroprotective Effect of HOTAIR Silencing on Isoflurane-Induced Cognitive Dysfunction via Sponging microRNA-129-5p and Inhibiting Neuroinflammation

INTRODUCTION

This article purposed to detect the function of the HOTAIR and HOTAIR/microRNA-129-5p (miR-129-5p) axis on the isoflurane (ISO)-injured cells and rat, and propounded a novel perspective in exploring the molecular pathogenesis of ISO damage.

METHODS

The expression of HOTAIR and miR-129-5p was tested by quantitative real-time PCR. The viable cells were identified using MMT, and the apoptotic cells were provided by flow cytometry. The concentration of proinflammatory indicators was revealed by enzyme-linked immunosorbent assay kits. The function of HOTAIR on oxidative stress was detected by commercial kits. A luciferase assay was performed to confirm the relationship between miR-129-5p and HOTAIR. The Morris water maze test was conducted to elucidate the cognition of SD rats.

RESULTS

The expression of HOTAIR was enhanced and the expression of miR-129-5p was lessened in the ISO-evoked SD rats and HT22 cells. The interference of HOTAIR reversed the injury of ISO on cell viability, apoptosis, inflammation, and oxidative stress. Besides, HOTAIR might be a target ceRNA of miR-129-5p. MiR-129-5p abrogated the function of silenced HOTAIR on cell viability, cell apoptosis, inflammation, and oxidative stress. Moreover, in vivo, the intervention of HOTAIR reversed the influence of ISO on cognition and oxidative stress by binding miR-129-5p.

DISCUSSION/CONCLUSION

Lowly expressed HOTAIR contributed to the recovery of the ISO-injured HT22 cell model from the abnormal viability, apoptosis, inflammation, and oxidative stress by regulating miR-129-5p. miR-129-5p mediated the function of HOTAIR on cognition and oxidative balance in the ISO-managed SD rat model.