Isoflurane-induced neuroapoptosis in the neonatal rhesus macaque brain

Postnatal Brain Trajectories and Maternal Intelligence Predict Childhood Outcomes in Complex CHD

Objective: To determine whether early structural brain trajectories predict early childhood neurodevelopmental deficits in complex CHD patients and to assess relative cumulative risk profiles of clinical, genetic, and demographic risk factors across early development. Study Design: Term neonates with complex CHDs were recruited at Texas Children's Hospital from 2005-2011. Ninety-five participants underwent three structural MRI scans and three neurodevelopmental assessments. Brain region volumes and white matter tract fractional anisotropy and radial diffusivity were used to calculate trajectories: perioperative, postsurgical, and overall. Gross cognitive, language, and visuo-motor outcomes were assessed with the Bayley Scales of Infant and Toddler Development and with the Wechsler Preschool and Primary Scale of Intelligence and Beery-Buktenica Developmental Test of Visual-Motor Integration. Multi-variable models incorporated risk factors. Results: Reduced overall period volumetric trajectories predicted poor language outcomes: brainstem ((β, 95% CI) 0.0977, 0.0382-0.1571; p = 0.0022) and white matter (0.0023, 0.0001-0.0046; p = 0.0397) at 5 years; brainstem (0.0711, 0.0157-0.1265; p = 0.0134) and deep grey matter (0.0085, 0.0011-0.0160; p = 0.0258) at 3 years. Maternal IQ was the strongest contributor to language variance, increasing from 37% at 1 year, 62% at 3 years, and 81% at 5 years. Genetic abnormality's contribution to variance decreased from 41% at 1 year to 25% at 3 years and was insignificant at 5 years. Conclusion: Reduced postnatal subcortical-cerebral white matter trajectories predicted poor early childhood neurodevelopmental outcomes, despite high contribution of maternal IQ. Maternal IQ was cumulative over time, exceeding the influence of known cardiac and genetic factors in complex CHD, underscoring the importance of heritable and parent-based environmental factors.

Structural MRI analysis of age-related changes and sex differences in marmoset brain volume

The field of aging biology, which aims to extend healthy lifespans and prevent age-related diseases, has turned its focus to the Callithrix jacchus (common marmoset) to understand the aging process better. This study utilized magnetic resonance imaging (MRI) to non-invasively analyze the brains of 216 marmosets, investigating age-related changes in brain structure; the relationship between body weight and brain volume; and potential differences between males and females. The key findings revealed that, similar to humans, Callithrix jacchus experiences a reduction in total intracranial volume, cortex, subcortex, thalamus, and cingulate volumes as they age, highlighting site-dependent changes in brain tissue. Notably, the study also uncovered sex differences in cerebellar volume. These insights into the structural connectivity and volumetric changes in the marmoset brain throughout aging contribute to accumulating valuable knowledge in the field, promising to inform future aging research and interventions for enhancing healthspan.

Anti-seizure medication-induced developmental cell death in neonatal rats is unaltered by history of hypoxia

BACKGROUND

Many anti-seizure medications (ASMs) trigger neuronal cell death when administered during a confined period of early life in rodents. Prototypical ASMs used to treat early-life seizures such as phenobarbital induce this effect, whereas levetiracetam does not. However, most prior studies have examined the effect of ASMs in naïve animals, and the degree to which underlying brain injury interacts with these drugs to modify cell death is poorly studied. Moreover, the degree to which drug-induced neuronal cell death differs as a function of sex is unknown.

METHODS

We treated postnatal day 7 Sprague Dawley rat pups with vehicle, phenobarbital (75 mg/kg) or levetiracetam (200 mg/kg). Separate groups of pups were pre-exposed to either normoxia or graded global hypoxia. Separate groups of males and females were used. Twenty-four hours after drug treatment, brains were collected and processed for markers of cell death.

RESULTS

Consistent with prior studies, phenobarbital, but not levetiracetam, increased cell death in cortical regions, basal ganglia, hippocampus, septum, and lateral thalamus. Hypoxia did not modify basal levels of cell death. Females - collapsed across treatment and hypoxia status, displayed a small but significant increase in cell death as compared to males in the cingulate cortex, somatosensory cortex, and the CA1 and CA3 hippocampus; these effects were not modulated by hypoxia or drug treatment.

CONCLUSION

We found that a history of graded global hypoxia does not alter the neurotoxic profile of phenobarbital. Levetiracetam, which does not induce cell death in normal developing animals, maintained a benign profile on the background of neonatal hypoxia. We found a sex-based difference, as female animals showed elevated levels of cell death across all treatment conditions. Together, these data address several long-standing gaps in our understanding of the neurotoxic profile of antiseizure medications during early postnatal development.

Effects of multiple anesthetic exposures on rhesus macaque brain development: a longitudinal structural MRI analysis

Concerns about the potential neurotoxic effects of anesthetics on developing brain exist. When making clinical decisions, the timing and dosage of anesthetic exposure are critical factors to consider due to their associated risks. In our study, we investigated the impact of repeated anesthetic exposures on the brain development trajectory of a cohort of rhesus monkeys (n = 26) over their first 2 yr of life, utilizing longitudinal magnetic resonance imaging data. We hypothesized that early or high-dose anesthesia exposure could negatively influence structural brain development. By employing the generalized additive mixed model, we traced the longitudinal trajectories of brain volume, cortical thickness, and white matter integrity. The interaction analysis revealed that age and cumulative anesthetic dose were variably linked to white matter integrity but not to morphometric measures. Early high-dose exposure was associated with increased mean, axial, and radial diffusivities across all white matter regions, compared to late-low-dose exposure. Our findings indicate that early or high-dose anesthesia exposure during infancy disrupts structural brain development in rhesus monkeys. Consequently, the timing of elective surgeries and procedures that require anesthesia for children and pregnant women should be strategically planned to account for the cumulative dose of volatile anesthetics, aiming to minimize the potential risks to brain development.

Early-in-life isoflurane exposure alters resting-state functional connectivity in juvenile non-human primates

BACKGROUND

Clinical studies suggest that anaesthesia exposure early in life affects neurobehavioural development. We designed a non-human primate (NHP) study to evaluate cognitive, behavioural, and brain functional and structural alterations after isoflurane exposure during infancy. These NHPs displayed decreased close social behaviour and increased astrogliosis in specific brain regions, most notably in the amygdala. Here we hypothesise that resting-state functional connectivity MRI can detect alterations in connectivity of brain areas that relate to these social behaviours and astrogliosis.

METHODS

Imaging was performed in 2-yr-old NHPs under light anaesthesia, after early-in-life (postnatal days 6-12) exposure to 5 h of isoflurane either one or three times, or to room air. Brain images were segmented into 82 regions of interest; the amygdala and the posterior cingulate cortex were chosen for a seed-based resting-state functional connectivity MRI analysis.

RESULTS

We found differences between groups in resting-state functional connectivity of the amygdala and the auditory cortices, medial premotor cortex, and posterior cingulate cortex. There were also alterations in resting-state functional connectivity between the posterior cingulate cortex and secondary auditory, polar prefrontal, and temporal cortices, and the anterior insula. Relationships were identified between resting-state functional connectivity alterations and the decrease in close social behaviour and increased astrogliosis.

CONCLUSIONS

Early-in-life anaesthesia exposure in NHPs is associated with resting-state functional connectivity alterations of the amygdala and the posterior cingulate cortex with other brain regions, evident at the juvenile age of 2 yr. These changes in resting-state functional connectivity correlate with the decrease in close social behaviour and increased astrogliosis. Using resting-state functional connectivity MRI to study the neuronal underpinnings of early-in-life anaesthesia-induced behavioural alterations could facilitate development of a biomarker for anaesthesia-induced developmental neurotoxicity.

Pediatric Microsurgery and Free-Tissue Transfer

Advancements in microsurgery, along with increased microsurgical experience in pediatric patients, have made free-tissue transfer a reliable modality for pediatric bone and soft tissue reconstruction today. Free-tissue transfer is most commonly used in children for the coverage of large or complex defects resulting from traumatic, oncologic, or congenital etiologies. While flap success and complication rates between pediatric and adult populations are similar, special considerations must be taken into account within the pediatric population. In this article, we will describe common indications, technical nuances, and clinical considerations for the management of the pediatric free-tissue transfer patient.

Spinal versus general anesthesia: Comparing outcomes in pediatric patients undergoing urologic procedures

INTRODUCTION

Available literature comparing spinal anesthesia (SA) to general anesthesia (GA) in the pediatric population describes multiple benefits in appropriately selected patients including cost reduction, lower incidence of complications, and shorter operative times. In patients undergoing urologic procedures, data are sparse.

OBJECTIVE

Our goal was to expand on the paucity of existing urologic literature as SA appears to be uniquely suited for a substantial number of its common pediatric procedures.

METHODS

Within a single institution, patients who had a urologic procedure performed under SA between May 2019 and July 2021 and were less than 18 months old were compared with a matched cohort of patients who had GA. The SA and GA groups were compared by two-sample t-tests, chi-square test for independence, and Fisher's exact test.

RESULTS

There were a total of 184 SA and 202 GA patients. There was no significant difference in the demographics except that SA patients were younger and weighed less than GA patients. The patients in the SA group needed less opioids both during the surgery (0% vs 26.1% p N/A) and in the immediate postoperative period when compared with GA patients (0% vs 18.2% p N/A). The patients who had SA had fewer complications necessitating PICU admission, or cancellation of surgery (0% vs 6.8% p = 0.03). Total anesthesia and emergence time were lower for SA patients (41 vs 50.2 p = 0.001 & 3.4 vs 6.1 p = 0.001). Both surgery and total OR time were not different between the groups (37.6 vs 35.5 p = 0.35 and 56.3 vs 54.4 p = 0.49). Overall, raw material cost was also found to be lower per procedure in the SA group vs the GA group ($8.90 vs $38.8: 77% reduction). Adjusted total mean costs for the surgery were not different between groups. The reduction in opioid use postoperatively also suggests reduced cost in the management of postoperative pain in the SA group.

DISCUSSION

Total anesthesia time, opioid use, and serious complications were all significantly lower in the SA group. We did not find significant difference in total surgery cost between two groups. However, patients who had SA had better pain control and needed less rescue analgesics in the immediate postoperative period. No patients in either group were sent home with opioids.

CONCLUSION

Spinal anesthesia was found to be an equally effective and appropriate alternative to GA with many proposed benefits for common pediatric urologic procedures. With further research, SA may prove to be a safer alternative in patients at risk for complications related to GA general anesthesia while also offering a cost benefit.

Behavioral and Cognitive Outcomes of Rhesus Macaques Following Neonatal Exposure to Antiseizure Medications

OBJECTIVE

Exposure of neonatal macaques to the antiseizure medications phenobarbital and midazolam (PbM) causes widespread apoptotic death of neurons and oligodendrocytes. We studied behavior and neurocognitive performance in 12 to 24 month-old macaques treated as neonates with PbM.

METHODS

A total of 14 monkeys received phenobarbital and midazolam over 24 hours under normothermia (n = 8) or mild hypothermia (n = 6). Controls (n = 8) received no treatment. Animals underwent testing in the human intruder paradigm at ages 12 and 18 months, and a 3-step stimulus discrimination task at ages 12, 18, and 24 months.

RESULTS

Animals treated with PbM displayed lower scores for environmental exploration, and higher scores for locomotion and vocalizations compared with controls. Combined PbM and hypothermia resulted in lower scores for aggression and vigilance at 12 months compared with controls and normothermic PbM animals. A mixed-effects generalized linear model was used to test for differences in neurocognitive performance between the control and PbM groups in the first step of the stimulus discrimination task battery (shape center baited to shape center non-baited). The odds of passing this step differed by group (p = 0.044). At any given age, the odds of passing for a control animal were 9.53-fold (95% CI 1.06-85) the odds for a PbM animal. There was also evidence suggesting a higher learning rate in the shape center non-baited for the control relative to the PbM group (Cox model HR 2.13, 95% CI 1.02-4.43; p = 0.044).

INTERPRETATION

These findings demonstrate that a 24-hour-long neonatal treatment with a clinically relevant combination of antiseizure medications can have long-lasting effects on behavior and cognition in nonhuman primates. ANN NEUROL 2023.

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.

Effects of anesthesia exposure on postnatal maturation of white matter in rhesus monkeys

There is increasing concern about the potential effects of anesthesia exposure on the developing brain. The effects of relatively brief anesthesia exposures used repeatedly to acquire serial magnetic resonance imaging scans could be examined prospectively in rhesus macaques. We analyzed magnetic resonance diffusion tensor imaging (DTI) of 32 rhesus macaques (14 females, 18 males) aged 2 weeks to 36 months to assess postnatal white matter (WM) maturation. We investigated the longitudinal relationships between each DTI property and anesthesia exposure, taking age, sex, and weight of the monkeys into consideration. Quantification of anesthesia exposure was normalized to account for variation in exposures. Segmented linear regression with two knots provided the best model for quantifying WM DTI properties across brain development as well as the summative effect of anesthesia exposure. The resulting model revealed statistically significant age and anesthesia effects in most WM tracts. Our analysis indicated there were major effects on WM associated with low levels of anesthesia even when repeated as few as three times. Fractional anisotropy values were reduced across several WM tracts in the brain, indicating that anesthesia exposure may delay WM maturation, and highlight the potential clinical concerns with even a few exposures in young children.

Anesthetics inhibit phosphorylation of the ribosomal protein S6 in mouse cultured cortical cells and developing brain

Introduction

The development and maintenance of neural circuits is highly sensitive to neural activity. General anesthetics have profound effects on neural activity and, as such, there is concern that these agents may alter cellular integrity and interfere with brain wiring, such as when exposure occurs during the vulnerable period of brain development. Under those conditions, exposure to anesthetics in clinical use today causes changes in synaptic strength and number, widespread apoptosis, and long-lasting cognitive impairment in a variety of animal models. Remarkably, most anesthetics produce these effects despite having differing receptor mechanisms of action. We hypothesized that anesthetic agents mediate these effects by inducing a shared signaling pathway.

Methods

We exposed cultured cortical cells to propofol, etomidate, or dexmedetomidine and assessed the protein levels of dozens of signaling molecules and post-translational modifications using reverse phase protein arrays. To probe the role of neural activity, we performed separate control experiments to alter neural activity with non-anesthetics. Having identified anesthetic-induced changes in vitro, we investigated expression of the target proteins in the cortex of sevoflurane anesthetized postnatal day 7 mice by Western blotting.

Results

All the anesthetic agents tested in vitro reduced phosphorylation of the ribosomal protein S6, an important member of the mTOR signaling pathway. We found a comparable decrease in cortical S6 phosphorylation by Western blotting in sevoflurane anesthetized neonatal mice. Using a systems approach, we determined that propofol, etomidate, dexmedetomidine, and APV/TTX all similarly modulate a signaling module that includes pS6 and other cell mediators of the mTOR-signaling pathway.

Discussion

Reduction in S6 phosphorylation and subsequent suppression of the mTOR pathway may be a common and novel signaling event that mediates the impact of general anesthetics on neural circuit development.

Progesterone alleviates esketamine-induced hypomyelination via PI3K/Akt signaling pathway in the developing rat brain

The neurodevelopmental toxicity of anesthetics has been confirmed repeatedly, and esketamine is now widely used in pediatric surgeries. Oligodendrocyte precursor cells (OPCs) evolved into mature oligodendrocytes (OLs) and formed myeline sheath during the early brain development. In this study, we investigated whether esketamine exposure interrupted development of OPCs and induced hypomyelination in rats. Further we explored the roles of PI3K/Akt phosphorylation in OPCs development and myelination. Sprague Dawley rats with different ages (postnatal day (P) 1, 3, 7 and 12) were exposed to 40mg/kg esketamine. Progesterone treatment was given (16 mg/kg per day for 3 days) 24 h after esketamine exposure via the intraperitoneal route. Corpus callosum tissues were collected at P8 or P14 for western blot and immunofluorescence analyses. Esketamine exposure at P7 and P12 significantly reduced myelin basic protein (MBP) expression and CC1+ OLs number in corpus callosum. Esketamine exposure at P7 not only aggravated the mature OLs apoptosis, also decreased the OPCs proliferation and differentiation, which was related with dephosphorylation of PI3K/Akt. Progesterone was able to promote OPCs differentiation and ameliorate esketamine-induced hypomyelination by enhancing PI3K/Akt phosphorylation. Stage-dependent abnormality of OPCs/OLs after esketamine leads to the esketamine-induced hypomyelination. Esketamine interrupted OPCs evolution via PI3K/Akt signaling pathway, which can be ameliorated by progesterone.

Alfaxalone Alleviates Neurotoxicity and Cognitive Impairment Induced by Isoflurane Anesthesia in Offspring Rats

BACKGROUND

The anesthetic isoflurane can cause neurotoxicity in fetuses and offspring of rats, affecting their neurodevelopment. However, the underlying mechanisms and therapeutic targets of isoflurane-induced neurotoxicity remain to be identified. Alfaxalone (ALF) is a steroid anesthetic. Steroids have been reported to have neuroprotective effects. This study aimed to investigate whether ALF could alleviate the isoflurane-induced neurotoxicity in fetuses and offspring of rats.

METHODS

On gestation day 15 (G15), the pregnant SD rats were randomly assigned to 4 groups: control 1 (CTL1) + control 2 (CTL2), isoflurane (ISO) + CTL2, CTL1 + ALF, and ISO + ALF. To analyze the changes in the expression levels of inflammatory cytokines, apoptotic factors, and synaptophysin, the brain tissues from the G15 fetuses and offspring at postnatal day 7 (P7), postnatal day 14 (P14), and postnatal day 31 (P31) were collected. The newborn neurons in the rats' offspring at P7, P14, and P31 were counted using immunofluorescence techniques. The Morris water maze (MWM) test was performed to assess the learning and memory abilities of P31 offspring rats.

RESULTS

ALF significantly alleviated the isoflurane-induced increase in the expression levels of inflammatory cytokines and apoptotic factors, such as interleukin (IL)-6 (ISO + CTL2 versus ISO + ALF: 5.133 ± 0.739 versus 1.093 ± 0.213, P < .001) and Caspase-3 (6.457 ± 0.6 versus 1.062 ± 0.1, P < .001) in the G15 fetuses. In P31 offspring rats, the expression levels of synaptophysin (0.719 ± 0.04 versus 1.068 ± 0.072, P < .001) and the number of newborn neurons in the dentate gyrus of the hippocampus were significantly lower in the ISO + CTL2 group as compared to those in the ISO + ALF group (118 ± 6 versus 140 ± 7, P < .001). These changes also occurred in the rat offspring at P7 and P14. In the MWM test, the escape latency of CTL1 + ALF group rats was significantly lower than that of ISO + ALF group rats (41 ± 6 versus 31 ± 7, P < .001) at P31.

CONCLUSIONS

Based on these findings, this study suggested that isoflurane exposure during pregnancy in rats could cause neuroinflammation and death of embryos as well as impairment of cognitive function in the offspring rats. ALF can be used to counteract the negative effects of isoflurane.

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.

Effects of Sevoflurane Exposure on Fetal Brain Development Using Cerebral Organoids

Sevoflurane is a safe and well-known inhaled anesthetic. Given that sevoflurane can be delivered to developing fetuses through the mother, it is critical to determine whether this agent affects fetal neurodevelopment. Recent research has sought to determine whether sevoflurane affects fetal brain development when the mother is exposed during the second to third trimester of pregnancy, considered to be the crucial period for the development of nervous system. However, even though the first trimester is a critical period for fetal organogenesis and the most susceptible time to teratogen exposure, research regarding the effects of sevoflurane on organogenesis, especially on brain development, is insufficient. In the present study, human embryonic stem cells (hESC)-derived cerebral organoids were exposed to sevoflurane during the time corresponding to the first trimester to investigate the effect of early sevoflurane exposure on fetal brain development, specifically the processes of neuronal differentiation and maturation. Organoid size exposed to the intermediate concentration of sevoflurane did not differ from control, immunofluorescence demonstrated that sevoflurane temporarily decreased the size of SOX2 + /N-cad + ventricular zone structures only during the mid-time point, and upregulated expression of TUJ1 and MAP2 only during the early time point. However, all markers returned to normal levels, and organoids formed normal cortical structures at the late time point. Our results suggest that maternal sevoflurane exposure during the first trimester of pregnancy can cause abnormal neuronal differentiation in the fetal brain. However, considering the recovery observed in later periods, sevoflurane exposure might not have lasting impacts on fetal brain development.

Neonatal Isoflurane Exposure in Rats Impairs Short-Term Memory, Cell Viability, and Glutamate Uptake in Slices of the Frontal Cerebral Cortex, But Not the Hippocampus, in Adulthood

Neonatal exposure to general anesthetics has been associated with neurotoxicity and morphologic changes in the developing brain. Isoflurane is a volatile anesthetic widely used in pediatric patients to induce general anesthesia, analgesia, and perioperative sedation. In the present study, we investigated the effects of a single neonatal isoflurane (3% in oxygen, 2 h) exposure in rats at postnatal day (PND) 7, in short-term (24 h - PND8) and long-term (adulthood) protocols. In PND8, ex vivo analysis of hippocampal and frontal cortex slices evaluated cell viability and susceptibility to in vitro glutamate challenge. In adult rats, behavioral parameters related to anxiety-like behavior, short-term memory, and locomotor activity (PND60-62) and ex vivo analysis of cell viability, membrane permeability, glutamate uptake, and susceptibility to in vitro glutamate challenge in hippocampal and cortical slices from PND65. A single isoflurane (3%, 2 h) exposure at PND7 did not acutely alter cell viability in cortical and hippocampal slices of infant rats (PND8) per se and did not alter slice susceptibility to in vitro glutamate challenge. In rat's adulthood, behavioral analysis revealed that the neonatal isoflurane exposure did not alter anxiety-like behavior and locomotor activity (open field and rotarod tests). However, isoflurane exposure impaired short-term memory evaluated in the novel object recognition task. Ex vivo analysis of brain slices showed isoflurane neonatal exposure selectively decreased cell viability and glutamate uptake in cortical slices, but it did not alter hippocampal slice viability or glutamate uptake (PND65). Isoflurane exposure did not alter in vitro glutamate-induced neurotoxicity to slices, and isoflurane exposure caused no significant long-term damage to cell membranes in hippocampal or cortical slices. These findings indicate that a single neonatal isoflurane exposure did not promote acute damage; however, it reduced cortical, but not hippocampal, slice viability and glutamate uptake in the adulthood. Additionally, behavioral analysis showed neonatal isoflurane exposure induces short-term recognition memory impairment, consolidating that neonatal exposure to volatile anesthetics may lead to behavioral impairment in the adulthood, although it may damage brain regions differentially.

Fetal and Neonatal Anesthesia

Anesthesia for fetal and neonatal surgery requires subspecialized knowledge and expertise. Attention to important anatomic, physiologic, and metabolic differences seen in pregnancy and at birth are essential for the optimal care of these patients. Thorough preoperative evaluations tailored intraoperative strategies and careful postoperative management are critical when devising the anesthetic approach for each of these cases.

Neonatal exposures to sevoflurane in rhesus monkeys alter synaptic ultrastructure in later life

Repeated or prolonged early life exposure to anesthesia is neurotoxic in animals and associated with neurocognitive impairment in later life in humans. We used electron microscopy with unbiased stereological sampling to assess synaptic ultrastructure in dorsolateral prefrontal cortex (dlPFC) and hippocampal CA1 of female and male rhesus monkeys, four years after three 4-h exposures to sevoflurane during the first five postnatal weeks. This allowed us to ascertain long-term consequences of anesthesia exposure without confounding effects of surgery or illness. Synapse areas were reduced in the largest synapses in CA1 and dlPFC, predominantly in perforated spinous synapses in CA1 and nonperforated spinous synapses in dlPFC. Mitochondrial morphology and localization changed subtly in both areas. Synapse areas in CA1 correlated with response to a mild social stressor. Thus, exposure to anesthesia in infancy can cause long-term ultrastructural changes in primates, which may be substrates for long-term alterations in synaptic transmission and behavioral deficits.

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.

Clinical factors associated with microstructural connectome related brain dysmaturation in term neonates with congenital heart disease

Objective

Term congenital heart disease (CHD) neonates display abnormalities of brain structure and maturation, which are possibly related to underlying patient factors, abnormal physiology and perioperative insults. Our primary goal was to delineate associations between clinical factors and postnatal brain microstructure in term CHD neonates using diffusion tensor imaging (DTI) magnetic resonance (MR) acquisition combined with complementary data-driven connectome and seed-based tractography quantitative analyses. Our secondary goal was to delineate associations between mild dysplastic structural brain abnormalities and connectome and seed-base tractography quantitative analyses. These mild dysplastic structural abnormalities have been derived from prior human infant CHD MR studies and neonatal mouse models of CHD that were collectively used to calculate to calculate a brain dysplasia score (BDS) that included assessment of subcortical structures including the olfactory bulb, the cerebellum and the hippocampus.

Methods

Neonates undergoing cardiac surgery for CHD were prospectively recruited from two large centers. Both pre- and postoperative MR brain scans were obtained. DTI in 42 directions was segmented into 90 regions using a neonatal brain template and three weighted methods. Clinical data collection included 18 patient-specific and 9 preoperative variables associated with preoperative scan and 6 intraoperative (e.g., cardiopulmonary bypass and deep hypothermic circulatory arrest times) and 12 postoperative variables associated with postoperative scan. We compared patient specific and preoperative clinical factors to network topology and tractography alterations on a preoperative neonatal brain MRI, and intra and postoperative clinical factors to network topology alterations on postoperative neonatal brain MRI. A composite BDS was created to score abnormal findings involving the cerebellar hemispheres and vermis, supratentorial extra-axial fluid, olfactory bulbs and sulci, hippocampus, choroid plexus, corpus callosum, and brainstem. The neuroimaging outcomes of this study included (1) connectome metrics: cost (number of connections) and global/nodal efficiency (network integration); (2) seed based tractography methods of fractional anisotropy (FA), radial diffusivity, and axial diffusivity. Statistics consisted of multiple regression with false discovery rate correction (FDR) comparing the clinical risk factors and BDS (including subcortical components) as predictors/exposures and the global connectome metrics, nodal efficiency, and seed based- tractography (FA, radial diffusivity, and axial diffusivity) as neuroimaging outcome measures.

Results

A total of 133 term neonates with complex CHD were prospectively enrolled and 110 had analyzable DTI. Multiple patient-specific factors including d-transposition of the great arteries (d-TGA) physiology and severity of impairment of fetal cerebral substrate delivery (i.e., how much the CHD lesion alters typical fetal circulation such that the highest oxygen and nutrient rich blood from the placenta are not directed toward the fetal brain) were predictive of preoperative reduced cost (p < 0.0073) and reduced global/nodal efficiency (p < 0.03). Cardiopulmonary bypass time predicted postoperative reduced cost (p < 0.04) and multiple postoperative factors [extracorporeal membrane oxygenation (ECMO), seizures and cardiopulmonary resuscitation (CPR)] were predictive of postoperative reduced cost and reduced global/nodal efficiency (p < 0.05). Anthropometric measurements (weight, length, and head size) predicted tractography outcomes. Total BDS was not predictive of brain network topology. However, key subcortical components of the BDS score did predict key global and nodal network topology: abnormalities of the cerebellum predicted reduced cost (p < 0.0417) and of the hippocampus predicted reduced global efficiency (p < 0.0126). All three subcortical structures predicted unique alterations of nodal efficiency (p < 0.05), including hippocampal abnormalities predicting widespread reduced nodal efficiency in all lobes of the brain, cerebellar abnormalities predicting increased prefrontal nodal efficiency, and olfactory bulb abnormalities predicting posterior parietal-occipital nodal efficiency.

Conclusion

Patient-specific (d-TGA anatomy, preoperative impairment of fetal cerebral substrate delivery) and postoperative (e.g., seizures, need for ECMO, or CPR) clinical factors were most predictive of diffuse postnatal microstructural dysmaturation in term CHD neonates. Anthropometric measurements (weight, length, and head size) predicted tractography outcomes. In contrast, subcortical components (cerebellum, hippocampus, olfactory) of a structurally based BDS (derived from CHD mouse mutants), predicted more localized and regional postnatal microstructural differences. Collectively, these findings suggest that brain DTI connectome and seed-based tractography are complementary techniques which may facilitate deciphering the mechanistic relative contribution of clinical and genetic risk factors related to poor neurodevelopmental outcomes in CHD.

Bumetanide attenuates sevoflurane-induced neuroapoptosis in the developing dentate gyrus and impaired behavior in the contextual fear discrimination learning test

INTRODUCTION

Sevoflurane acts as a gamma-aminobutyric acid subtype A receptor agonist and can induce widespread apoptosis of immature dentate granule cells in postnatal day 21 mice. The dentate granule cells of postnatal day 21 mice undergo a developmental stage when gamma-aminobutyric acid (GABA) shifts from inducing the depolarization of neurons to causing hyperpolarization. However, it is unclear whether sevoflurane induces apoptosis of immature granule cells by facilitating the depolarization or hyperpolarization of neurons.

METHODS

We utilized bumetanide, an Na⁺ -K⁺ -2Cl^- cotransporter isoform 1 (NKCC1) antagonist, to determine whether the NKCC1-mediated GABA depolarization of neurons plays a role in sevoflurane-induced neuroapoptosis. We also investigated whether sevoflurane exposure is related to long-term cognitive dysfunction in postnatal day 21 mice and explored the possible protective effects of bumetanide.

RESULTS

Bumetanide attenuated the sevoflurane-induced apoptosis of dentate granule cells in postnatal day 21 mice. Exposure to sevoflurane at postnatal day 21 mice did not affect their motor ability or anxiety level, and it had no effect on spatial learning or memory functions. However, sevoflurane exposure at postnatal day 21 impaired the pattern separation ability in the contextual fear discrimination test; bumetanide mitigated this effect of sevoflurane as well.

CONCLUSION

Bumetanide attenuates sevoflurane-induced apoptosis and is a promising prospect for protecting against anesthesia-induced neurotoxicity in the developing brain.

Insulin signaling in the central nervous system, a possible pathophysiological mechanism of anesthesia-induced delayed neurocognitive recovery/postoperative neurocognitive disorder: a narrative review

INTRODUCTION

Impairment in neurocognitive functions ranges between delayed neurocognitive recovery (DNR) and postoperative neurocognitive disorders (pNCD). Incidence varies from 11% after noncardiac surgery to 60% after cardiac surgery.

AREAS COVERED

Insulin receptors (IRs) signaling pathway in the central nervous system (CNS) could be a possible pathophysiological mechanism of anesthesia-induced DNR/pNCD and perioperative intranasal insulin administration could be a preventive approach. This hypothesis is supported by the following evidence: effects of IRs-CNS signaling pathway on neuromodulation; higher incidence of DNR/pNCD in patients with insulin resistance; neurotoxicity of IRs signaling pathways after anesthetic exposure; improvement of neurocognitive impairment after insulin exposure. This narrative review was conducted after a literature search of PubMed, EMBASE and SCOPUS online medical data performed in May 2022.

EXPERT OPINION

Perioperative intranasal insulin is shown to be protective and future studies should address: the role of insulin as a neuromodulator; its integration into neuroprotection approaches; patient populations that might benefit from this approach; a well-defined protocol of intranasal insulin administration in a perioperative background and other disciplines; and possible collateral effects.

Mild hypothermia fails to protect infant macaques from brain injury caused by prolonged exposure to Antiseizure drugs

Barbiturates and benzodiazepines are GABA_A-receptor agonists and potent antiseizure medications. We reported that exposure of neonatal macaques to combination of phenobarbital and midazolam (Pb/M) for 24 h, at clinically relevant doses and plasma levels, causes widespread apoptosis affecting neurons and oligodendrocytes. Notably, the extent of injury was markedly more severe compared to shorter (8 h) exposure to these drugs. We also reported that, in the infant macaque, mild hypothermia ameliorates the apoptosis response to the anesthetic sevoflurane. These findings prompted us explore whether mild hypothermia might protect infant nonhuman primates from neuro- and gliotoxicity of Pb/M. Since human infants with seizures may receive combinations of benzodiazepines and barbiturates for days, we opted for 24 h treatment with Pb/M. Neonatal rhesus monkeys received phenobarbital intravenously, followed by midazolam infusion over 24 h under normothermia (T > 36.5 °C-37.5 °C; n = 4) or mild hypothermia (T = 35 °C-36.5 °C; n = 5). Medication doses and blood levels measured were comparable to those in human infants. Animals were euthanized at 36 h and brains examined immunohistochemically and stereologically. Treatment was well tolerated. Extensive degeneration of neurons and oligodendrocytes was seen at 36 h in both groups within neocortex, basal ganglia, hippocampus and brainstem. Mild hypothermia over 36 h (maintained until terminal perfusion) conferred no protection against the neurotoxic and gliotoxic effects of Pb/M. This is in marked contrast to our previous findings that mild hypothermia is protective in the context of a 5 h-long exposure to sevoflurane in infant macaques. These findings demonstrate that brain injury caused by prolonged exposure to Pb/M in the neonatal primate cannot be ameliorated by mild hypothermia.

The impact of early exposure to general anesthesia on visual and neurocognitive development

Every year millions of children are exposed to general anesthesia while undergoing surgical and diagnostic procedures. In the field of ophthalmology, 44,000 children are exposed to general anesthesia annually for strabismus surgery alone. While it is clear that general anesthesia is necessary for sedation and pain minimization during surgical procedures, the possibility of neurotoxic impairments from its exposure is of concern. In animals there is strong evidence linking early anesthesia exposure to abnormal neural development. but in humans the effects of anesthesia are debated. In humans many aspects of vision develop within the first year of life, making the visual system vulnerable to early adverse experiences and potentially vulnerable to early exposure to general anesthesia. We attempt to address whether the visual system is affected by early postnatal exposure to general anesthesia. We first summarize key mechanisms that could account for the neurotoxic effects of general anesthesia on the developing brain and review existing literature on the effects of early anesthesia exposure on the visual system in both animals and humans and on neurocognitive development in humans. Finally, we conclude by proposing future directions for research that could address unanswered questions regarding the impact of general anesthesia on visual development.

Protective effects of chlorogenic acid on isoflurane‐induced cognitive impairment of aged mice

Postoperative cognitive dysfunction (POCD) is characterized by impairment in cognitive functions in patients following anesthesia and surgery. Chlorogenic acid (CGA) is a plant‐derived compound possessing numerous bioactive properties. The aim of this study was to investigate the therapeutic potential of CGA in isoflurane (ISO)‐induced cognitive dysfunction of aged mice, and further identify the mechanisms involved in the protective effects of CGA. A total of 80 male C57BL/6 mice, 20‐month‐old, were randomly divided into control group, isoflurane group (ISO), and ISO + 30 mg/kg CGA group and ISO + 60 mg/kg CGA. CGA was given orally once daily for 7 days to the mice and they were exposed to ISO (1.5%; 4 h). The open‐field and Morris water maze tests were used to investigate the cognitive function of mice. Pretreatment with CGA significantly attenuated ISO‐induced cognitive impairment. The levels of IL‐1β, TNF‐α, IL‐6, nuclear p65 NF‐kB, cleaved caspase‐3, and Bax were significantly increased, while the levels of IkBα and Bcl‐2 were decreased in the hippocampus 24 h after the ISO anesthesia. All the mentioned effects induced by ISO were reversed by CGA pretreatment. Furthermore, ISO exposure induced marked downregulation of SOD, CAT, HO‐1, and NQO‐1 and elevation of MDA and nuclear translocation of Nrf2 in the hippocampus tissue. All these parameters were reversed by CGA treatment. Importantly, the higher dose of CGA (60 mg/kg) showed a greater neuroprotective effect. In conclusion, these findings suggest that CGA attenuates the ISO‐induced cognitive impairment via its anti‐inflammatory, anti‐oxidative, and anti‐apoptotic properties in aged mice.

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

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

Effect of Anesthesia on Oligodendrocyte Development in the Brain

Oligodendrocytes (OLs) participate in the formation of myelin, promoting the propagation of action potentials, and disruption of their proliferation and differentiation leads to central nervous system (CNS) damage. As surgical techniques have advanced, there is an increasing number of children who undergo multiple procedures early in life, and recent experiments have demonstrated effects on brain development after a single or multiple anesthetics. An increasing number of clinical studies showing the effects of anesthetic drugs on the development of the nervous system may mainly reside in the connections between neurons, where myelin development will receive more research attention. In this article, we review the relationship between anesthesia exposure and the brain and OLs, provide new insights into the development of the relationship between anesthesia exposure and OLs, and provide a theoretical basis for clinical prevention of neurodevelopmental risks of general anesthesia drugs.

Neonatal Anesthesia and Oxidative Stress

Neonatal anesthesia, while often essential for surgeries or imaging procedures, is accompanied by significant risks to redox balance in the brain due to the relatively weak antioxidant system in children. Oxidative stress is characterized by concentrations of reactive oxygen species (ROS) that are elevated beyond what can be accommodated by the antioxidant defense system. In neonatal anesthesia, this has been proposed to be a contributing factor to some of the negative consequences (e.g., learning deficits and behavioral abnormalities) that are associated with early anesthetic exposure. In order to assess the relationship between neonatal anesthesia and oxidative stress, we first review the mechanisms of action of common anesthetic agents, the key pathways that produce the majority of ROS, and the main antioxidants. We then explore the possible immediate, short-term, and long-term pathways of neonatal-anesthesia-induced oxidative stress. We review a large body of literature describing oxidative stress to be evident during and immediately following neonatal anesthesia. Moreover, our review suggests that the short-term pathway has a temporally limited effect on oxidative stress, while the long-term pathway can manifest years later due to the altered development of neurons and neurovascular interactions.

Does Resveratrol Prevent Sevoflurane Toxicity in Newborn Rats?

Inhalation anesthetics have been shown to cause neurodevelopmental disorders and neurotoxic effects. In this study, we aimed to investigate the effect of resveratrol on the possible neurotoxic effect of sevoflurane and the brain-derived neurotrophic factor (BDNF) pathway in newborn rats. The animals were divided into four groups: control, sevoflurane, sevoflurane+resveratrol 25 mg/kg, and sevoflurane+resveratrol 50 mg/kg. The groups that received anesthesia were given 3% sevoflurane for 2 h on the postnatal seventh, eighth, and ninth days. Control gas was applied to the control group. The Morris water maze (MWM) test was performed on postnatal 35th day. After performing the open field test on the postnatal 41st day, the animals were dissected, and the hippocampal BDNF levels were determined by Western blot method. In the MWM test, there was a significant decrease in the time spent in the target quadrant in the sevoflurane anesthesia group compared with control group. This reduction was reversed with the resveratrol pretreatment. Sevoflurane exposure significantly decreased hippocampal BDNF levels compared with the control group. The resveratrol 25 mg/kg pretreatment did not reverse this reduction, whereas resveratrol 50 mg/kg ameliorated this impairment. Sevoflurane did not cause any significant difference in the rats' performance in the open field test. However, 50 mg/kg resveratrol pretreatment caused a statistically significant increase in this performance. Our results showed that sevoflurane impaired learning and memory functions in newborn rats and resveratrol reversed this deterioration. Also BDNF might play a role in this beneficial effect of resveratrol.

Sevoflurane-Induced Apoptosis in the Mouse Cerebral Cortex Follows Similar Characteristics of Physiological Apoptosis

General anesthetics are capable of inducing neuronal apoptosis during the rapid synaptogenesis of immature mammalian brains. In this vulnerable time window, physiological apoptosis also occurs to eliminate excess and inappropriately integrated neurons. We previously showed that physiological and ketamine-induced apoptosis in mouse primary somatosensory cortex (S1) followed similar developmental patterns. However, since sevoflurane is more widely used in pediatric anesthesia, and targets mainly on different receptors, as compared with ketamine, it is important to determine whether sevoflurane-induced apoptosis also follows similar developmental patterns as physiological apoptosis or not. Mice at postnatal days 5 (P5) and P9 were anesthetized with 1.5% sevoflurane for 4 h, and the apoptotic neurons in S1 were quantitated by immunohistochemistry. The results showed that sevoflurane raised the levels of apoptosis in S1 without interfering with the developmental patterns of physiological apoptosis. The cells more vulnerable to both physiological and sevoflurane-induced apoptosis shifted from layer V pyramidal neurons at P5 to layers II–IV GABAergic neurons by P9. The magnitude of both sevoflurane-induced and physiological apoptosis was more attenuated at P9 than P5. To determine whether the Akt-FoxO1-PUMA pathway contributes to the developmental decrease in magnitude of both physiological and sevoflurane-induced apoptosis, Western blot was used to measure the levels of related proteins in S1 of P5 and P9 mice. We observed higher levels of antiapoptotic phosphorylated Akt (p-Akt) and phosphorylated FoxO1 (p-FoxO1), and lower levels of the downstream proapoptotic factor PUMA in control and anesthetized mice at P9 than P5. In addition, the Akt-FoxO1-PUMA pathway may also be responsible for sevoflurane-induced apoptosis. Together, these results suggest that magnitude, lamination pattern and cell-type specificity to sevoflurane-induced apoptosis are age-dependent and follow physiological apoptosis pattern. Moreover, The Akt-FoxO1-PUMA pathway may mediate the developmental decreases in magnitude of both physiological and sevoflurane-induced apoptosis in neonatal mouse S1.

Anesthesia and neurotoxicity study design, execution, and reporting in the nonhuman primate: A systematic review

BACKGROUND

Concern for a role of anesthesia in neurotoxicity in children originated from neonatal rodent and nonhuman primate (NHP) models, yet prospective clinical studies have largely not supported this concern. The goal of this study was to conduct an objective assessment of published NHP study rigor in design, execution, and reporting.

METHODS

A MEDLINE search from 2005 to December 2021 was performed. Inclusion criteria included full-length original studies published in English under peer-reviewed journals. We documented experimental parameters on anesthetic dosing, monitoring, vitals, and experimental outcomes.

RESULTS

Twenty-three manuscripts were included. Critical issues identified in study design included: lack of blinding in data acquisition (57%) and analysis (100%), supratherapeutic (4-12 fold) maintenance dosing in 22% of studies, lack of sample size justification (91%) resulting in a mean (SD) sample size of 6 (3) animals per group. Critical items identified in the conduct and reporting of studies included: documentation of anesthesia provider (0%), electrocardiogram monitoring (35%), arterial monitoring (4%), spontaneous ventilation employed (35%), failed intubations resulting in comingling ventilated and unventilated animals in data analysis, inaccurate reporting of failed intubation, and only 50% reporting on survival. Inconsistencies were noted in drug-related induction of neuroapoptosis and region of occurrence. Further, 67%-100% of behavior outcomes were not significantly different from controls.

CONCLUSIONS

Important deficits in study design, execution, and reporting were identified in neonatal NHP studies. These results raise concern for the validity and reliability of these studies and may explain in part the divergence from results obtained in human neonates.

Application of Nonhuman Primate Models in the Studies of Pediatric Anesthesia Neurotoxicity

Numerous animal models have been used to study developmental neurotoxicity associated with short-term or prolonged exposure of common general anesthetics at clinically relevant concentrations. Pediatric anesthesia models using the nonhuman primate (NHP) may more accurately reflect the human condition because of their phylogenetic similarity to humans with regard to reproduction, development, neuroanatomy, and cognition. Although they are not as widely used as other animal models, the contribution of NHP models in the study of anesthetic-induced developmental neurotoxicity has been essential. In this review, we discuss how neonatal NHP animals have been used for modeling pediatric anesthetic exposure; how NHPs have addressed key data gaps and application of the NHP model for the studies of general anesthetic-induced developmental neurotoxicity. The appropriate application and evaluation of the NHP model in the study of general anesthetic-induced developmental neurotoxicity have played a key role in enhancing the understanding and awareness of the potential neurotoxicity associated with pediatric general anesthetics.

Gastroschisis: Impact of Bedside Closure on Ventilator-Associated Outcomes

AIM

 In our practice, preformed silos are routine rather than reserved for difficult cases. We aimed to identify whether silo and bedside closure can minimize: general anesthetic (GA) exposure, need for intubation and ventilation, or days intubated for neonates with simple gastroschisis (SG).

METHODS

 After approval, patients were identified via the neonatal discharge log (April 2010 to April 2019). Data were collected by case-note review and analyzed with respect to GA, ventilation, and core outcomes.

RESULTS

 Of 104 patients (50 female, mean birth weight 2.43 kg, mean gestational age 36 + 2 weeks), 85 were SG and 19 complex. Silo application was initial management in 70 SG, 57 completed successful bedside closure (by day 4 of life-median). Fifteen SG had initial operative closure.Of the 70 SG managed with silo, 46 (66%) had no GA as neonates. Twelve required GA for line insertion. Thirteen patients with initial silo had closure in theater (7 opportunistic at time of GA for line). Nine required intubation and ventilation out-with the operating theater during neonatal management. Seven had already been intubated at delivery; 3 because of meconium aspiration.One-hundred percent of those treated with operative closure had GA, 1 patient subsequently required surgery for subglottic stenosis. Time to full feeds did not differ between groups.

CONCLUSION

 Silo and bedside closure allow the majority of SG neonates to avoid GA or intubation in the neonatal period, without increased risk of complication. However, it is important that the nursing expertise required to manage these patients safely is not underestimated.

The Protective Effect of Notoginsenoside R1 on Isoflurane-Induced Neurological Impairment in the Rats via Regulating miR-29a Expression and Neuroinflammation

INTRODUCTION

Isoflurane inhalation leads to apoptotic neurodegeneration and further results in learning and cognitive dysfunction. Notoginsenoside R1 (NGR1), a major ingredient from Radix notoginseng, has been reported to exert neuroprotective effect during brain or neuron injury. This study aimed to investigate the effect of NGR1 on neurological impairment.

METHODS

Sixty-four male Sprague Dawley rat pups (15-20 g) of postnatal day 7 were recruited. Spatial learning and memory were assessed by the Morris water maze test, and the neurological severity score was determined. Real-time quantitative PCR was used to detect the expression levels of microRNA (miR)-29a. Enzyme-linked immunosorbent assay was applied to estimate the levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the hippocampal tissues.

RESULTS

NGR1 attenuated neurological impairment induced by isoflurane, shown by the decrease in neurological function score and escape latency and the increase in staying time in the original quadrant in rats. NGR1 reversed the downregulation of miR-29a expression induced by isoflurane treatment. After the treatment of NGR1, the elevated levels of IL-6, TNF-α, and IL-1β induced by isoflurane were all decreased significantly in the hippocampal tissues of rats. Additionally, the repressive action of NGR1 in neurological impairment and neuroinflammation was eliminated by downregulating miR-29a in rats.

CONCLUSION

NGR1 protects against isoflurane-induced neurological impairment. The protective effect of NGR1 might be achieved by promoting the expression of miR-29a and preventing inflammatory response.

The Protective Effect of Picroside II on Isoflurane-Induced Neuronal Injury in Rats via Downregulating miR-195

INTRODUCTION

Numerous pieces of evidence demonstrated that isoflurane induces hippocampal cell injury and cognitive impairments. Picroside II has been investigated for its anti-apoptosis and antioxidant neuroprotective effects. We aimed to explore the protective effects of picroside II and the role of microRNA-195 (miR-195) on isoflurane-induced neuronal injury in rats.

METHODS

The Morris water maze test was used to evaluate the effects of isoflurane on rats regarding escape latency and time in quadrant parameters. Real-time quantitative PCR was used to detect the expression levels of miR-195 and pro-inflammatory cytokines, including inter-leukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) mRNA, in the hippocampal tissues and neuronal cells.

RESULTS

The picroside II significantly improves isoflurane-induced higher escape latency and lower time spent in the quadrant compared with the control rats. Picroside II also promotes cell viability and suppresses cell apoptosis of isoflurane-induced neuronal cells. Besides, picroside II suppresses the expression of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and miR-195 in vivo and in vitro. Furthermore, overexpression of miR-195 abrogates the effects of picroside II on the expression of pro-inflammatory cytokines. The appropriate dose of picroside II is 20 mg/kg.

CONCLUSION

Picroside II could protect the nervous system possibly through inhibiting the inflammatory response in the isoflurane-induced neuronal injury of rats. The protective effect of picroside II may be achieved by downregulating the expression of miR-195 and then inhibiting the inflammatory response.

Early Development of the GABAergic System and the Associated Risks of Neonatal Anesthesia

Human and animal studies have elucidated the apparent neurodevelopmental effects resulting from neonatal anesthesia. Observations of learning and behavioral deficits in children, who were exposed to anesthesia early in development, have instigated a flurry of studies that have predominantly utilized animal models to further interrogate the mechanisms of neonatal anesthesia-induced neurotoxicity. Specifically, while neonatal anesthesia has demonstrated its propensity to affect multiple cell types in the brain, it has shown to have a particularly detrimental effect on the gamma aminobutyric acid (GABA)ergic system, which contributes to the observed learning and behavioral deficits. The damage to GABAergic neurons, resulting from neonatal anesthesia, seems to involve structure-specific changes in excitatory-inhibitory balance and neurovascular coupling, which manifest following a significant interval after neonatal anesthesia exposure. Thus, to better understand how neonatal anesthesia affects the GABAergic system, we first review the early development of the GABAergic system in various structures that have been the focus of neonatal anesthesia research. This is followed by an explanation that, due to the prolonged developmental curve of the GABAergic system, the entirety of the negative effects of neonatal anesthesia on learning and behavior in children are not immediately evident, but instead take a substantial amount of time (years) to fully develop. In order to address these concerns going forward, we subsequently offer a variety of in vivo methods which can be used to record these delayed effects.

MRI Protocol for Pituitary Assessment in Children with Growth or Puberty Disorders-Is Gadolinium Contrast Administration Actually Needed?

The aim of this study was to assess the diagnostic value of non-contrast pituitary MRI in children with growth or puberty disorders (GPDs) and to determine the criteria indicating the necessity to perform post-contrast examination. A retrospective study included re-analysis of 567 contrast-enhanced pituitary MRIs of children treated in a tertiary reference center. Two sets of sequences were created from each MRI examination: Set 1, including common sequences without contrast administration, and Set 2, which included common pre- and post-contrast sequences (conventional MRI examination). The differences in the visibility of pituitary lesions between pairs of sets were statistically analyzed. The overall frequency of Rathke’s cleft cysts was 11.6%, ectopic posterior pituitary 3.5%, and microadenomas 0.9%. Lesions visible without contrast administration accounted for 85% of cases. Lesions not visible before and diagnosed only after contrast injection accounted for only 0.18% of all patients. Statistical analysis showed the advantage of the antero-posterior (AP) pituitary dimension over the other criteria in determining the appropriateness of using contrast in pituitary MRIs. The AP dimension was the most significant factor in logistic regression analysis: OR = 2.23, 95% CI, 1.35–3.71, p-value = 0.002, and in ROC analysis: AUC: 72.9% with a cut-off value of 7.5 mm, with sensitivity/specificity rates of 69.2%/73.5%. In most cases, the use of gadolinium-based contrast agent (GBCA) in pituitary MRI in children with GPD is unnecessary. The advantages of GBCA omission include shortening the time of MRI examination and of general anesthesia; saving time for other examinations, thus increasing the availability of MRI for waiting children; and acceleration in their further clinical management.

Comparative Milestones in Rodent and Human Postnatal Central Nervous System Development

Within the substantially different time scales characterizing human and rodent brain development, key developmental processes are remarkably preserved. Shared processes include neurogenesis, myelination, synaptogenesis, and neuronal and synaptic pruning. In general, altricial rodents experience greater central nervous system (CNS) immaturity at birth and accelerated postnatal development compared to humans, in which protracted development of certain processes such as neocortical myelination and synaptic maturation extend into adulthood. Within this generalization, differences in developmental rates of various structures must be understood to accurately model human neurodevelopmental toxicity in rodents. Examples include greater postnatal neurogenesis in rodents, particularly within the dentate gyrus of rats, ongoing generation of neurons in the rodent olfactory bulb, differing time lines of neurotransmitter maturation, and differing time lines of cerebellar development. Comparisons are made to the precocial guinea pig and the long-lived naked mole rat, which, like primates, experiences more advanced CNS development at birth, with more protracted postnatal development. Methods to study various developmental processes are summarized using examples of comparative postnatal injury in humans and rodents.

Fraxetin suppresses reactive oxygen species-dependent autophagy by the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells

Isoflurane, a common volatile anesthetic, has been widely used to provide general anesthesia in operations. However, exposure to isoflurane may cause widespread neurotoxicity in the developing animal brain. Fraxetin, a natural coumarin derivative extracted from the bark of Fraxinus rhynchophylla, possesses versatile pharmacological properties including anti-oxidative, anti-inflammatory, and neuroprotective effects. However, the effect and action mechanism of fraxetin on neurotoxicity induced by isoflurane are unknown. Reactive oxygen species (ROS) generation, cell viability, lactate dehydrogenase (LDH) release, and apoptosis were estimated by 2',7'-dichlorofluorescin-diacetate (DCFH-DA) staining, MTT, LDH release, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining assays, respectively. The protein levels of light chain 3 (LC3)-I, LC3-II, p62, protein kinase B (Akt), and phosphorylated Akt (p-Akt) were detected by western blot analysis. Isoflurane induced ROS, LDH release, apoptosis, and autophagy, but inhibited the viability in HT22 cells, which were overturned by fraxetin or ROS scavenger N-acetyl-L-cysteine. Fraxetin suppressed isoflurane-induced PI3K/Akt inactivation in HT22 cells. PI3K/Akt inactivation by LY294002 resisted the effects of fraxetin on isoflurane-induced autophagy and autophagy-modulated neurotoxicity in HT22 cells. In conclusion, fraxetin suppressed ROS-dependent autophagy by activating the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells.

Update on the safety of anesthesia in young children presenting for adenotonsillectomy

Tonsillectomy with and without adenoidectomy is a frequently performed surgical procedure in children. Although a common procedure, it is not without significant risk. It is critical for anesthesiologists to consider preoperative, intraoperative, and postoperative patient factors and events to optimize safety, especially in young children. In the majority of cases, the indication for adenotonsillectomy in young children is obstructive breathing. Preoperative evaluation for patient comorbidities, especially obstructive sleep apnea, risk factors for a difficult airway, and history of recent illness are crucial to prepare the patient for surgery and develop an anesthetic plan. Communication and collaboration with the otolaryngologist is key to prevent and treat intraoperative events such as airway fires or hemorrhage. Postoperative analgesia planning is critical for safe pain control especially for those patients with a history of obstructive sleep apnea and opioid sensitivity. In young children, it is important to also consider the impact of anesthetic medications on the developing brain. This is an area of continuing research but needs to be weighed when planning for surgical treatment and when discussing risks and benefits with patients' families.

An Investigation of the Long and Short Term Behavioral Effects of General Anesthesia on Pediatric Dental Patients With Autism

Purpose: The purpose of this study was to compare the incidence of short and long term adverse behavioral effects of general anesthesia (GA) in healthy vs. moderate to severe autistic (ASD) children.

Methods: Forty healthy and 37 ASD children, aged 3–17 years, undergoing GA for dental surgery participated in this study. Their anesthesia records were reviewed, and their parents answered telephone surveys to assess activity level, sleep disturbances, gastrointestinal disturbances, central nervous system effects, and respiratory depression. Three follow-up surveys were taken 8 h, 24 h, and 3 months post-surgery.

Results: Four hundred fifty-five incidences of adverse behavioral effects occurred within 8 h post-surgery. Significantly more ASD patients had difficulty walking (P = 0.016) and nausea (P = 0.030), while more healthy children snored in the car ride home (P = 0.036) and talked about the dental surgery (P = 0.027). Three months post-discharge, sixASD patients acted in a way that concerned caregivers compared to 0 healthy patients, (P = 0.008). Incidence of adverse behavioral effects significantly decreased from 8 to 24 h overall.

Conclusions: Most behavioral effects occur within 8 h post-surgery. There are potential long term adverse behavioral effects in ASD children from GA, but the chance is low and generally not long lasting.

Effects of general anesthetics on synaptic transmission and plasticity

General anesthetics depress excitatory and/or enhance inhibitory synaptic transmission principally by modulating the function of glutamatergic or GABAergic synapses, respectively, with relative anesthetic agent-specific mechanisms. Synaptic signaling proteins, including ligand- and voltage-gated ion channels, are targeted by general anesthetics to modulate various synaptic mechanisms, including presynaptic neurotransmitter release, postsynaptic receptor signaling, and dendritic spine dynamics to produce their characteristic acute neurophysiological effects. As synaptic structure and plasticity mediate higher-order functions such as learning and memory, long-term synaptic dysfunction following anesthesia may lead to undesirable neurocognitive consequences depending on the specific anesthetic agent and the vulnerability of the population. Here we review the cellular and molecular mechanisms of transient and persistent general anesthetic alterations of synaptic transmission and plasticity.

Oxidative Stress as a Common Key Event in Developmental Neurotoxicity

The developing brain is extremely sensitive to many chemicals. Perinatal exposure to neurotoxicants has been implicated in several neurodevelopmental disorders, including autism spectrum disorder, attention-deficit hyperactive disorder, and schizophrenia. Studies of the molecular and cellular events related to developmental neurotoxicity have identified a number of “adverse outcome pathways,” many of which share oxidative stress as a key event. Oxidative stress occurs when the balance between the production of free oxygen radicals and the activity of the cellular antioxidant system is dysregulated. In this review, we describe some of the developmental neurotoxins that target the antioxidant system and the mechanisms by which they elicit stress, including oxidative phosphorylation in mitochondria and plasma membrane redox system in rodent models. We also discuss future directions for identifying adverse outcome pathways related to oxidative stress and developmental neurotoxicity, with the goal of improving our ability to quickly and accurately screen chemicals for their potential developmental neurotoxicity.

Neonatal Anesthesia and dysregulation of the Epigenome

Each year, millions of infants and children are anesthetized for medical and surgical procedures. Yet, a substantial body of preclinical evidence suggests that anesthetics are neurotoxins that cause rapid and widespread apoptotic cell death in the brains of infant rodents and non-human primates. These animals have persistent impairments in cognition and behavior many weeks or months after anesthesia exposure, leading us to hypothesize that anesthetics do more than simply kill brain cells. Indeed, anesthetics cause chronic neuropathology in neurons that survive the insult, which then interferes with major aspects of brain development, synaptic plasticity, and neuronal function. Understanding the phenomenon of anesthesia-induced developmental neurotoxicity is of critical public health importance because clinical studies now report that anesthesia in human infancy is associated with cognitive and behavioral deficits. In our search for mechanistic explanations for why a young and pliable brain cannot fully recover from a relatively brief period of anesthesia, we have accumulated evidence that neonatal anesthesia can dysregulate epigenetic tags that influence gene transcription such as histone acetylation and DNA methylation. In this review, we briefly summarize the phenomenon of anesthesia-induced developmental neurotoxicity. We then discuss chronic neuropathology caused by neonatal anesthesia, including disturbances in cognition, socio-affective behavior, neuronal morphology, and synaptic plasticity. Finally, we present evidence of anesthesia-induced genetic and epigenetic dysregulation within the developing brain that may be transmitted intergenerationally to anesthesia-naïve offspring.

Astrogliosis in juvenile non-human primates 2 years after infant anaesthesia exposure

BACKGROUND

Infant anaesthesia causes acute brain cell apoptosis, and later in life cognitive deficits and behavioural alterations, in non-human primates (NHPs). Various brain injuries and neurodegenerative conditions are characterised by chronic astrocyte activation (astrogliosis). Glial fibrillary acidic protein (GFAP), an astrocyte-specific protein, increases during astrogliosis and remains elevated after an injury. Whether infant anaesthesia is associated with a sustained increase in GFAP is unknown. We hypothesised that GFAP is increased in specific brain areas of NHPs 2 yr after infant anaesthesia, consistent with prior injury.

METHODS

Eight 6-day-old NHPs per group were exposed to 5 h isoflurane once (1×) or three times (3×), or to room air as a control (Ctr). Two years after exposure, their brains were assessed for GFAP density changes in the primary visual cortex (V1), perirhinal cortex (PRC), hippocampal subiculum, amygdala, and orbitofrontal cortex (OFC). We also assessed concomitant microglia activation and hippocampal neurogenesis.

RESULTS

Compared with controls, GFAP densities in V1 were increased in exposed groups (Ctr: 0.208 [0.085-0.427], 1×: 0.313 [0.108-0.533], 3×: 0.389 [0.262-0.652]), whereas the density of activated microglia was unchanged. In addition, GFAP densities were increased in the 3× group in the PRC and the subiculum, and in both exposure groups in the amygdala, but there was no increase in the OFC. There were no differences in hippocampal neurogenesis among groups.

CONCLUSIONS

Two years after infant anaesthesia, NHPs show increased GFAP without concomitant microglia activation in specific brain areas. These long-lasting structural changes in the brain caused by infant anaesthesia exposure may be associated with functional alterations at this age.

The Protective Effects of Benzbromarone Against Propofol-Induced Inflammation and Injury in Human Brain Microvascular Endothelial Cells (HBMVECs)

It has been widely reported that severe neurotoxicity can be induced by the application of propofol, which is closely related to the disruption of the blood-brain barrier (BBB) induced by inflammation and injury in the human brain microvascular endothelial cells (HBMVECs). Benzbromarone is a classic anti-gout agent that has been recently reported to exert anti-inflammatory and anti-oxidative stress effects. In the present study, we aim to investigate the protective property of Benzbromarone against propofol-induced injury on HBMVECs and the underlying mechanism. CCK8 assay was used to detect the cell viability of treated HBMVECs. Oxidative stress in HBMVECs was evaluated by measuring the levels of MDA and mitochondrial ROS. ELISA and qRT-PCR assay were used to determine the production of IL-1β, IL-8, MCP-1, ICAM-1, and VCAM-1 by treated HBMVECs. Calcein-AM staining was utilized to evaluate the attachment of U937 monocytes to HBMVECs. The expression level of Egr-1 was determined by qRT-PCR and Western blot assay. Firstly, the decreased cell viability of HBMVECs induced by propofol was significantly elevated by treatment with Benzbromarone. The increased levels of MDA and mitochondrial ROS induced by propofol were dramatically suppressed by Benzbromarone. Secondly, the excessive production of inflammatory factors (IL-1β, IL-8, and MCP-1) and adhesion molecules (ICAM-1 and VCAM-1) triggered by propofol was pronouncedly inhibited by Benzbromarone. Benzbromarone ameliorated propofol-induced attachment of U937 monocytes to HBMVECs. Lastly, Benzbromarone downregulated propofol-induced expression of the transcriptional factor Egr-1 in HBMVECs. Benzbromarone protected against propofol-induced inflammation and injury through suppressing Egr-1 in human brain vascular endothelial cells.