Blockade of NMDA receptors and apoptotic neurodegeneration in the developing brain

Balancing efficacy and safety: The dual impact of antiseizure medications on the developing brain

The number of neurons in the developing brain is greater than typically found in adulthood, and the brain possesses delicate mechanisms to induce the death of excess cells and refine neural circuitry. The correct tuning between the processes of neuronal death and survival generates a mature and functional brain in its complexity and plastic capacity. Epilepsy is a highly prevalent neurological condition worldwide, including among young individuals. However, exposure to the main treatment approaches, the long-term use of Antiseizure Medication (ASM), during the critical period of development can induce a series of changes in this delicate balance. Acting by various mechanisms of action, ASMs may induce an increase in neuronal death, something that translates into deleterious neuropsychiatric effects in adulthood. Several investigations conducted in recent years have brought to light new aspects related to this dynamic, yet many questions, such as the cellular mechanisms of death and the pathophysiology of late effects, still have unresolved elements. In this review, we aimed to explore the mechanisms of action of the most widely used ASMs in the treatment of neonatal epilepsy, the broad aspects of neuronal death in the developing brain and the repercussions of this death and other effects in adulthood. We review the evidence indicating a relationship between exposure to ASMs and the manifestation of associated psychiatric comorbidities in adulthood and discuss some possible mechanisms underlying the induction of this process by morphological and physiological changes in the related behaviors.

Acute and Long-Term Consequences of Neonatal NMDA Blockade in the Cx3cr1 Knock-Out Mouse

Neuron-microglia communication through the fractalkine pathway is a critical factor mediating microglial proliferation, migration, release of mediators, and clearance of cellular debris, as well as the function of neuronal NMDA receptors. Disruption of the fractalkine-mediated microglia-neuron communication is associated with divergent outcomes, from damaging to protective, in different neurological conditions (including schizophrenia and epilepsy). In the present work we explore the impact of the absence of the fractalkine receptor (CX3CR1) after neonatal blockade of NMDA receptors, which induces acute and long-term alterations in behavior, neuronal integrity and excitability. Wild-type (WT) and Cx3cr1-/- (KO) mice of both sexes randomly received either a low (0.5 mg/kg) or high dose (1 mg/kg) of MK-801 (NMDA receptor antagonist) or saline, for five consecutive days, during early postnatal development. Neuronal apoptosis was assessed at a midpoint of the pharmacological protocol. Survival and growth rates were determined up to adulthood when innate behaviors, unconditioned anxiety, contextual memory and seizure susceptibility were evaluated, as well as hippocampal local field potential and sensory gating. CX3CR1 depletion and neonatal MK-801 treatment had a synergistic acute effect, increasing neuronal apoptosis and overall mortality. Both factors independently induced long-lasting impairments in the wide array of behavioral tasks assessed during adulthood. However, low MK-801 dose treatment greatly augmented the mortality of pentylenetetrazol-induced seizures in WT mice, an effect prevented by CX3CR1 depletion. MK-801 treatment induced a shift in the power spectrum of the hippocampal local field potential towards higher frequencies that was averted in Cx3cr1-/- mice by an opposite shift. Our results reveal that CX3CR1 depletion severely increases the vulnerability to neonatal NMDA antagonism with additional complex interactions regarding cognitive and neurophysiological effects, which should be considered in the context of neuron-microglia miscommunication in many neurological disorders including schizophrenia and epilepsy.

Effects of neonatal N-methyl-D-aspartate receptor blockade on social facilitation of feeding behavior in adult rats

Glutamate and one of its ionotropic receptor subtypes, N-methyl-D-aspartate (NMDA) receptors, are essential for brain development after birth. Rats that underwent NMDA receptor blockade during the neonatal period have been validated as models of schizophrenia. Social facilitation, a phenomenon where an individual's performance is promoted in the presence of others, reflects the ability to regulate behavior depending on social situations and is likely to be disrupted in schizophrenia. This study investigated the effects of neonatal treatment with MK-801, an NMDA receptor antagonist, on the social facilitation of feeding behavior in adult rats. Under noncompetitive conditions, SAL-treated control rats showed increased food intake when feeding with another rat, whereas MK-801-treated rats did not. Under competitive conditions, SAL-treated rats tended to feed more in the presence of a competitor compared to feeding alone. In contrast, MK-801-treated rats exhibited a significant reduction in food intake in the presence of a competitor. Thus, MK-801-treated rats demonstrated a lack of social facilitation under noncompetitive conditions and social inhibition under competitive conditions. These findings suggest that neonatal NMDA receptor blockade disrupts the ability of rats to regulate their behavior depending on their social situation. Our findings may provide new insights into the social deficits associated with schizophrenia and their underlying mechanisms.

Cognitive, motor, and behavioral outcomes in preterm infants exposed to opioids

BACKGROUND

Preterm infants undergo multiple painful procedures, which may negatively affect neurodevelopment. Proper pain management, including opioid use, is essential. This study aimed to determine the impact of opioid administration in very and extremely preterm infants on cognitive, motor, and behavioral outcomes at the corrected age of 3 years.

METHODS

This retrospective, single-center study included preterm infants born between 23 and 32 weeks of gestation, admitted to the Medical University of Vienna between 2011 and 2017. Follow-up data were collected at 3 years corrected age. Primary outcomes included behavioral outcomes assessed by the Child Behavior Checklist (CBCL) and cognitive and motor outcomes using the Bayley Scales of Infant Development (BSID).

RESULTS

A total of 333 preterm infants were included, with 214 in the non-opioid group (no exposure to opioids) and 119 in the opioid-group (exposure to opioids). Significant differences in cognitive and motor scores were observed between the groups (92.5 (85.5-98.5) vs 88 (79-94) and 85 (76-96) vs 76 (67-85), both p = 0.001). Behavioral outcomes were within the normal range in both groups, although higher depressive scores were noted in the opioid group.

CONCLUSIONS

Cumulative opioid exposure in neonatal care may negatively impact cognitive and motor development but did not significantly affect overall behavioral outcomes.

IMPACT

Our findings suggest that cumulative opioid exposure in the NICU does not significantly influence overall behavioral problems at the age of 3 years. However, it poses a risk for altered cognitive and motor development. This study highlights the distinct effects of opioid exposure on motor development and cognitive outcomes, while offering a nuanced perspective on behavioral outcomes, filling gaps in understanding the long-term neurodevelopmental consequences in preterm infants. The findings emphasize the need for careful management of opioid administration in NICU settings, balancing pain relief with potential long-term neurodevelopmental risks, while also underscoring the role of confounding factors such as IVH in shaping developmental trajectories.

Impact of sevoflurane anesthesia on S-adenosylmethionine in neonates under general anesthesia

Background and Aims

Preclinical studies in rodents and primates have shown that anesthesia was neurotoxic to the developing brain after exposure in the neonatal period. Sevoflurane a commonly used inhalational anesthetic, especially in pediatric surgery, might cause behavioral impairment in the developing brain. Although favored for its rapid onset and minimal airway disturbance, sevoflurane has been implicated in neurotoxic effects such as anesthesia-induced developmental neurotoxicity in rodents, through various mechanisms. One of the mechanisms was disturbances in methylation metabolism which can be easily treated if it is proved. This study aims to evaluate the levels of S-adenosylmethionine [SAM] following sevoflurane anesthesia in neonates and to correlate the duration of sevoflurane exposure and S-adenosylmethionine levels.

Material and Methods

Sixty neonates were included in the study under general anesthesia. Pre- and postsevoflurane exposure arterial blood samples were collected in ethylenediamine tetraacetic acid vacutainers. Each sample was centrifuged at 1000 rpm for 10 min. Plasma was separated and stored at -80°C, then subjected to S-adenosylmethionine enzyme-linked immunoassay test for preand postsevoflurane exposure levels of SAM.

Results

The difference between the pre- and post-SAM values is not statistically significant and also with increasing the duration of sevoflurane exposure there was no reduction in the SAM levels (r = 0.17), and the correlation was not significant (P = 0.18).

Conclusion

Single exposure to sevoflurane does not impact SAM levels in neonates undergoing general anesthesia.

Cell death in glioblastoma and the central nervous system

Glioblastoma is the commonest and deadliest primary brain tumor. Glioblastoma is characterized by significant intra- and inter-tumoral heterogeneity, resistance to treatment and dismal prognoses despite decades of research in understanding its biological underpinnings. Encompassed within this heterogeneity and therapy resistance are severely dysregulated programmed cell death pathways. Glioblastomas recapitulate many neurodevelopmental and neural injury responses; in addition, glioblastoma cells are composed of multiple different transformed versions of CNS cell types. To obtain a greater understanding of the features underlying cell death regulation in glioblastoma, it is important to understand the control of cell death within the healthy CNS during homeostatic and neurodegenerative conditions. Herein, we review apoptotic control within neural stem cells, astrocytes, oligodendrocytes and neurons and compare them to glioblastoma apoptotic control. Specific focus is paid to the Inhibitor of Apoptosis proteins, which play key roles in neuroinflammation, CNS cell survival and gliomagenesis. This review will help in understanding glioblastoma as a transformed version of a heterogeneous organ composed of multiple varied cell types performing different functions and possessing different means of apoptotic control. Further, this review will help in developing more glioblastoma-specific treatment approaches and will better inform treatments looking at more direct brain delivery of therapeutic agents.

Effects of Xenon on the Developing Brain: Current Insights from Pre-clinical and Clinical Studies

Research has indicated that general anesthetics may potentially induce neuroapoptosis, resulting in long-term neurological deficits in the developing brain. Fortunately, xenon, a noble gas, emerges as a promising candidate for an ideal anesthetic due to its favorable properties, offering neuroprotection and mitigating the neurotoxic effects of other general anesthetics during early life stages. Nevertheless, it is important to highlight that xenon has also been observed to cause neuroapoptosis in the neonatal brain, suggesting that xenon possesses both neuroprotective qualities (as evidenced by pre-clinical and clinical studies) and neurotoxic potential (based mainly on pre-clinical evidence) during brain development. To gain a comprehensive understanding the effects xenon, this review will explore the anesthetic properties of xenon, examine its effects on anesthesia, and elucidate its mechanisms of potential neuroprotection and neurotoxicity in the developing brain. The primary emphasis will be on xenon's application in the context of anesthetic-induced developmental neurotoxicity (AIDN), hypoxic-ischemic encephalopathy (HIE), and teratogenicity, aiming to provide valuable insights for pediatricians, pediatric anesthesiologists, and other healthcare professionals involved in the use and study of xenon anesthesia.

Visceral Pain in Preterm Infants with Necrotizing Enterocolitis: Underlying Mechanisms and Implications for Treatment

Necrotizing enterocolitis (NEC) is a relatively rare but very severe gastrointestinal disease primarily affecting very preterm infants. NEC is characterized by excessive inflammation and ischemia in the intestines, and is associated with prolonged, severe visceral pain. Despite its recognition as a highly painful disease, current pain management for NEC is often inadequate, and research on optimal analgesic therapy for these patients is lacking. Insight into the mechanisms underlying intestinal pain in infants with NEC-visceral pain-could help identify the most effective analgesics for these vulnerable patients. Therefore, this comprehensive review aims to provide an overview of visceral nociception, including transduction, transmission, modulation, and experience, and discuss the implications for analgesic therapy in preterm infants with NEC. The transmission of visceral pain differs from that of somatic pain, contributing to the diffuse nature of visceral pain. Studies evaluating the effectiveness of analgesics for treating visceral pain in infants are scarce. However, research in visceral pain models highlights agents that may be particularly effective for treating visceral pain based on their mechanisms of action. Further research is necessary to determine whether agents that have shown promise for treating visceral pain in preclinical studies and adults are effective in infants with NEC as well.

Maternal exposure to general anesthesia and labor epidural analgesia during pregnancy and delivery, and subsequent neurodevelopmental outcomes in children

Gestation is a vulnerable developmental period, and exposures during that time may have longterm implications. While evaluating the implications of early exposures on children is an important public health concern, as opposed to other chemical exposures, medications are given for a clinical purpose, and any potential injury must be weighed against the benefits of these medications to the mother and child. This review examines neurodevelopmental outcomes in children following two maternal anesthetic exposures: general anesthesia and labor epidural analgesia. Exposure to general anesthetic agents has been found to interfere with neurodevelopment in animal models, and exposures in children, including prenatal exposures are also associated with worse neurodevelopmental outcomes. While these medications are likely to impact neurodevelopment in animals, it remains unclear if prenatal general anesthetic exposure causes the reported differences in children. As a result, since avoidance or delay of necessary surgery in mothers may result in adverse outcomes in mothers and children, necessary surgery in pregnant mothers should proceed without delay. Concerns about the safety of maternal neuraxial labor analgesia ("epidurals") have also emerged due to a reported association with autism spectrum diagnoses in their children. This may be due to familial factors in pregnant women electing for neuraxial labor analgesia rather than the "epidural" itself. In addition, since clinically significant differences in neurodevelopmental scores in children following exposure have not been found, and a mechanism of injury has not yet been identified in preclinical studies, the benefits of neuraxial labor analgesia appear to outweigh the potential risks.

Inflammatory signaling pathways in Alzheimer's disease: Mechanistic insights and possible therapeutic interventions

The complex pathophysiology of Alzheimer's disease (AD) poses challenges for the development of therapies. Recently, neuroinflammation has been identified as a key pathogenic mechanism underlying AD, while inflammation has emerged as a possible target for the management and prevention of AD. Several prior studies have demonstrated that medications modulating neuroinflammation might lessen AD symptoms, mostly by controlling neuroinflammatory signaling pathways such as the NF-κB, MAPK, NLRP3, etc, and their respective signaling cascade. Moreover, targeting these inflammatory modalities with inhibitors, natural products, and metabolites has been the subject of intensive research because of their anti-inflammatory characteristics, with many studies demonstrating noteworthy pharmacological capabilities and potential clinical applications. Therefore, targeting inflammation is considered a promising strategy for treating AD. This review comprehensively elucidates the neuroinflammatory mechanisms underlying AD progression and the beneficial effects of inhibitors, natural products, and metabolites in AD treatment.

Two distinct enriched housings differentially ameliorate object and place recognition deficits in a rat model of schizophrenia

Schizophrenia is a psychiatric disorder characterized by cognitive dysfunctions. These dysfunctions significantly impact the daily lives of schizophrenic patients, yet effective interventions remain scarce. In this study, we explored the effects of two enriched housing types-cognitive and physical-on cognitive dysfunctions in a rat model of schizophrenia. Male neonatal Wistar-Imamichi rats were administered MK-801, a noncompetitive NMDAR antagonist, twice daily from postnatal day (PND) 7 to PND 20. Physical enrichment ameliorated memory deficits in both object and place recognition tests, while cognitive enrichment primarily improved object recognition performance. Our findings suggest that exercise therapy could be a potential approach to address cognitive dysfunctions in schizophrenia patients.

Unraveling the effects of prenatal anesthesia on neurodevelopment: A review of current evidence and future directions

Human brain development is a complex, multi-stage, and sensitive process, especially during the fetal stage. Animal studies over the last two decades have highlighted the potential risks of anesthetics to the developing brain, impacting its structure and function. This has raised concerns regarding the safety of anesthesia during pregnancy and its influence on fetal brain development, garnering significant attention from the anesthesiology community. Although preclinical studies predominantly indicate the neurotoxic effects of prenatal anesthesia, these findings cannot be directly extrapolated to humans due to interspecies variations. Clinical research, constrained by ethical and technical hurdles in accessing human prenatal brain tissues, often yields conflicting results compared to preclinical data. The emergence of brain organoids as a cutting-edge research tool shows promise in modeling human brain development. When integrated with single-cell sequencing, these organoids offer insights into potential neurotoxic mechanisms triggered by prenatal anesthesia. Despite several retrospective and cohort studies exploring the clinical impact of anesthesia on brain development, many findings remain inconclusive. As such, this review synthesizes preclinical and clinical evidence on the effects of prenatal anesthesia on fetal brain development and suggests areas for future research advancement.

Children and the Opioid Crisis: We Can Make a Difference

The use of opioid-sparing and opioid-free strategies in children can provide adequate analgesia while decreasing the risk of adverse events and contributing to the ongoing battle against the opioid crisis. However, every child must be evaluated individually so that a safe and efficacious perioperative pain management plan can be created. A working knowledge of the risks and benefits of opioids, nonopioid adjuncts, and regional anesthesia along with the ethical considerations for balancing stewardship and beneficent care is essential to the success of these strategies. As perioperative practitioners caring for children, we have an obligation to consider opioid-sparing and opioid-free strategies to promote overall best outcomes. We can make a difference, one child at a time.

Sevoflurane exposure in early life: mitochondrial dysfunction and neurotoxicity in immature rat brains without long-term memory loss

Neurotoxic effects of general anesthetics, particularly sevoflurane, on pediatric neurodevelopment are a global concern. This study investigated the molecular and metabolic impacts of repeated short exposures to sevoflurane in neonatal rats. Metabolomics analysis revealed significant changes in fatty acid and mitochondrial energy metabolism. Transcriptomic analysis identified altered gene expression related to neurodevelopment and mitochondrial function. Various analyses emphasized upregulation in oxidative phosphorylation and DNA repair pathways. Weighted gene co-expression network analysis (WGCNA) identified key gene modules associated with sevoflurane exposure. Despite these acute changes, no significant long-term memory impairments were detected. These findings highlight the impact of sevoflurane on mitochondrial energy metabolism, oxidative stress, and neuroinflammation, emphasizing its relevance to pediatric neurodevelopment. The absence of substantial long-term memory impairments provides insights into the safety and implications of sevoflurane use in pediatric anesthesia, calling for further research.

Dexmedetomidine directly binds to and inhibits Toll-like receptor 4

BACKGROUND

While a number of anesthetics has been shown potentially associated with neurotoxicity in the developing brain, dexmedetomidine, a drug that was rather recently introduced into the perioperative setting, is considered beneficial from neurological wellbeing. However, the underlying mechanism of how dexmedetomidine affects brain health remains to be determined. Based on our recent study, we hypothesized that dexmedetomidine would directly bind to and inhibit Toll-like receptor 4 (TLR4), a critical receptor largely expressed in microglia and responsible for neurological insult.

METHODS

We used TLR4 reporter assays to test if dexmedetomidine attenuates TLR4 activation. Furthermore, a direct binding of dexmedetomidine on TLR4 was tested using photoactivatable medetomidine. Lastly, the effect of dexmedetomidine on ketamine (anesthetic)-induced neurotoxicity was tested in rat pups (P7).

RESULTS

We showed that dexmedetomidine attenuated TLR4 activation using reporter assay (IC50 = 5.8 µg/mL). Photoactivatable dexmedetomidine delineated its direct binding sites on TLR4. We also showed that dexmedetomidine attenuated microglia activation both in vitro and in vivo.

DISCUSSION

We proposed a novel mechanism of dexmedetomidine-mediated neuroprotection.

Association between general anesthesia in early childhood and neurodevelopment up to 4 years of age: the Japan Environment and Children's Study

PURPOSE

The effects of general anesthesia on neurodevelopment in children remain controversial. We explored the relationship between general anesthesia and neurodevelopment in children participating in the Japan Environment and Children's Study (JECS).

METHODS

This study enrolled children born between 37 and 41 weeks of pregnancy via single-vaginal delivery to pregnant women registered in the JECS between January 2011 and March 2014. Data were collected from mother-completed questionnaires and medical transcripts. Neurodevelopment in five domains was assessed every 6 months between 12 and 48 months of age, using the Ages and Stages Questionnaires. The associations between general anesthesia exposure during early childhood and neurodevelopment in children were evaluated at each time point. Adjusted odds ratios and 95% confidence intervals were estimated after covariate adjustment using logistic regression models.

RESULTS

Children who received general anesthesia before age 1 year had higher risks of neurodevelopmental delay in all five domains throughout the observational period. The largest risk was for gross motor delay at 18 months (adjusted odds ratio: 3.51; 95% confidence interval: 2.75-4.49). The effects on the incidence of neurodevelopmental delays after age 3 were not observed except for problem solving at 48 months. The risk of neurodevelopmental delay in children who first received general anesthesia after age 1 was considerably small.

CONCLUSIONS

This study suggests that general anesthesia administration before age 1 is associated with neurodevelopmental delay during 1-4 years of age. The risk of general anesthesia after age 1 may be small.

NMDA Receptors: Distribution, Role, and Insights into Neuropsychiatric Disorders

BACKGROUND

N-methyl-D-aspartate receptors (NMDARs) are members of the ionotropic glutamate receptor family. These ligand-gated channels are entwined with numerous fundamental neurological functions within the central nervous system (CNS), and numerous neuropsychiatric disorders may arise from their malfunction.

METHODS

The purpose of the present review is to provide a detailed description of NMDARs by addressing their molecular structures, activation mechanisms, and physiological roles in the mammalian brain. In the second part, their role in various neuropsychiatric disorders including stroke, epilepsy, anti-NMDA encephalitis, Alzheimer's and Huntington's diseases, schizophrenia, depression, neuropathic pain, opioid-induced tolerance, and hyperalgesia will be covered.

RESULTS

Finally, through a careful exploration of the main non-competitive NMDARs antagonists (channel-blockers).

CONCLUSION

We discuss the strengths and limitations of the various molecular structures developed for diagnostic or therapeutic purposes.

A single exposure to brivaracetam or perampanel does not cause cell death in neonatal rats

Introduction

Exposure to a range of anti-seizure medications (ASMs) during early brain development adversely impacts neurodevelopmental outcomes in both animal models and in clinical studies. Many ASMs, including phenobarbital, phenytoin, valproate (VPA), and benzodiazepines, are associated with acute neurotoxicity (cell death), impaired synaptic development, and long-term behavioral changes following gestational or neonatal exposure in animals. This is mirrored in clinical studies which show lasting neurodevelopmental deficits following early-life or gestational exposure to these drugs. Brivaracetam (BRV) and perampanel (PER) are two newer generation anti-seizure medications and are of interest based on their mechanisms of action (SV2A modulator, AMPA antagonist, respectively), as other drugs with these mechanisms of action do not trigger acute neurotoxicity. Both BRV and PER show anti-seizure efficacy in developing animals, but potential neurotoxicity of these drugs is unexplored.

Methods

To address this gap, we treated postnatal day (P)7 Sprague-Dawley rats with BRV (20, 40, 80 mg/kg) and PER (0.1, 0.9, 2.7 mg/kg), and assessed the induction of cell death across a range of vulnerable brain regions 24 h after exposure. Cell death was assessed using pathogreen staining.

Results

In each of the regions examined (dorsal striatum, nucleus accumbens, motor cortex, cingulate cortex, lateral thalamus, septum, hippocampus), VPA, which served as a positive control, significantly increased cell death as measured by the numer of pathogreen positive cells. By contrast, neither BRV nor PER increased the number of pathogreen positive cells in any region examined.

Discussion

Our results suggest that BRV and PER may have a positive safety profile-at least with respect to acute induction of cell death - and therefore may offer a safer option for the treatment of early life seizures.

Sedation and anesthesia for imaging of the infant and neonate-a brief review

Sedation and anesthesia are often required in order to facilitate collection of high-quality imaging studies free of significant motion artifact for infants and neonates. Provision of safe sedation and anesthesia requires good communication between the ordering provider, radiologist, and anesthesiologist, careful pre-procedural evaluation of the patient, and availability of appropriate and sufficient equipment, drugs, personnel, and facilities. There are many additional factors to be considered for provision of safe sedation or anesthesia for infants and neonates-it is ideal to involve a fellowship-trained pediatric anesthesiologist in the planning and carry-out of these plans. In this review, we discuss some of the basic definitions of sedation and anesthesia, requirements for safe sedation and anesthesia, and many of the germane risks and additional considerations that factor into the delivery of a safe sedation or anesthesia plan for the imaging of an infant or neonate.

GABAergic and inflammatory changes in the frontal cortex following neonatal PCP plus isolation rearing, as a dual-hit neurodevelopmental model for schizophrenia

The pathogenesis of schizophrenia begins in early neurodevelopment and leads to excitatory-inhibitory imbalance. It is therefore essential that preclinical models used to understand disease, select drug targets and evaluate novel therapeutics encompass similar neurochemical deficits. One approach to improved preclinical modelling incorporates dual-hit neurodevelopmental insults, like neonatal administration of phencyclidine (PCP, to disrupt development of glutamatergic circuitry) then post-weaning isolation (Iso, to mimic adolescent social stress). We recently showed that male Lister-hooded rats exposed to PCP-Iso exhibit reduced hippocampal expression of the GABA interneuron marker calbindin. The current study expanded on this by investigating changes to additional populations of GABAergic interneurons in frontal cortical and hippocampal tissue from the same animals (by immunohistochemistry) as well as levels of GABA itself (via ELISA). Because inflammatory changes are also implicated in schizophrenia, we performed additional immunohistochemical evaluations of Iba-1 positive microglia as well as ELISA analysis of IL-6 in the same brain regions. Single-hit isolation-reared and dual-hit PCP-Iso rats both showed reduced parvalbumin immunoreactivity in the prelimbic/infralimbic region of the frontal cortex. However, this was more widespread in PCP-Iso, extending to the medial/ventral and lateral/dorsolateral orbitofrontal cortices. Loss of GABAergic markers was accompanied by increased microglial activation in the medial/ventral orbitofrontal cortices of PCP-Iso, together with frontal cortical IL-6 elevations not seen following single-hit isolation rearing. These findings enhance the face validity of PCP-Iso, and we advocate the use of this preclinical model for future evaluation of novel therapeutics-especially those designed to normalise excitatory-inhibitory imbalance or reduce neuroinflammation.

Inhalation of hydrogen gas mitigates sevoflurane-induced neuronal apoptosis in the neonatal cortex and is associated with changes in protein phosphorylation

Inhalation of hydrogen (H2) gas is therapeutically effective for cerebrovascular diseases, neurodegenerative disorders, and neonatal brain disorders including pathologies induced by anesthetic gases. To understand the mechanisms underlying the protective effects of H2 on the brain, we investigated the molecular signals affected by H2 in sevoflurane-induced neuronal cell death. We confirmed that neural progenitor cells are susceptible to sevoflurane and undergo apoptosis in the retrosplenial cortex of neonatal mice. Co-administration of 1-8% H2 gas for 3 h to sevoflurane-exposed pups suppressed elevated caspase-3-mediated apoptotic cell death and concomitantly decreased c-Jun phosphorylation and activation of the c-Jun pathway, all of which are induced by oxidative stress. Anesthesia-induced increases in lipid peroxidation and oxidative DNA damage were alleviated by H2 inhalation. Phosphoproteome analysis revealed enriched clusters of differentially phosphorylated proteins in the sevoflurane-exposed neonatal brain that included proteins involved in neuronal development and synaptic signaling. H2 inhalation modified cellular transport pathways that depend on hyperphosphorylated proteins including microtubule-associated protein family. These modifications may be involved in the protective mechanisms of H2 against sevoflurane-induced neuronal cell death.

Effects of Antipsychotics on the Hypothalamus-Pituitary-Adrenal Axis in a Phencyclidine Animal Model of Schizophrenia

Schizophrenia (SCH) is a mental disorder that requires long-term antipsychotic treatment. SCH patients are thought to have an increased sensitivity to stress. The dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, observed in SCH, could include altered levels of glucocorticoids, glucocorticoid receptors (GRs), and associated proteins. The perinatal administration of phencyclidine (PCP) to rodents represents an animal model of SCH. This study investigated the effects of perinatal PCP exposure and subsequent haloperidol/clozapine treatment on corticosterone levels measured by ELISA and the expression of GR-related proteins (GR, pGR, HSP70, HSP90, FKBP51, and 11β-Hydroxysteroid dehydrogenase-11β-HSD) determined by Western blot, in different brain regions of adult rats. Six groups of male rats were treated on the 2nd, 6th, 9th, and 12th postnatal days (PN), with either PCP or saline. Subsequently, one saline and one PCP group received haloperidol/clozapine from PN day 35 to PN day 100. The results showed altered GR sensitivity in the rat brain after PCP exposure, which decreased after haloperidol/clozapine treatment. These findings highlight disturbances in the HPA axis in a PCP-induced model of SCH and the potential protective effects of antipsychotics. To the best of our knowledge, this is the first study to investigate the effects of antipsychotic drugs on the HPA axis in a PCP animal model of SCH.

A Comparison of Pre- and Post-Treatment Cranial MRI Characteristics in Patients with Pediatric Epilepsy Receiving Levetiracetam

Background and Objectives: This study was performed for the purpose of assessing whether antiepileptic levetiracetam treatment produces a change in brain volumes in children with epilepsy. To that end, we compared the volumes of the basal ganglia (caudate nucleus, putamen, globus, hip-pocampus, and thalamus) at magnetic resonance imaging (MRI) before and after treatment (months 18-24) in pediatric epilepsy patients using levetiracetam. Materials and Methods: This retrospective study involved a volumetric comparison of patients presenting to the Balikesir University Medical Faculty pediatric neurology clinic between 01.08.2019 and 01.11.2023 and diagnosed with epilepsy, and who underwent cranial MRI before and 18-24 months after treatment at the radiology department. The demographic and clinical characteristics (age, sex, family history of epilepsy, type of epilepsy, and EEG features (normal, abnormal, epileptiform)) of the patients included in the study were recorded. Results: The comparison of basal ganglia volumes at cranial MRI before and at months 18-24 of treatment revealed significant differences in the left caudate nucleus, right putamen, left putamen, left globus pallidus, right thalamus, left thalamus, and right hippocampal regions. Conclusions: In conclusion, differing findings are encountered at cranial imaging in patients with epilepsy, depending on the seizure frequency, activity, and the type of antiepileptic drugs used. This study compared basal ganglia volumes on cranial MRIs taken before and 18-24 months after treatment in pediatric epilepsy patients using levetiracetam. A significant increase was observed in the volumes of basal ganglia (caudate nucleus, putamen, globus pallidus, hippocampus, and thalamus) on the MRIs of pediatric epilepsy patients using levetiracetam.

The role of taurine through endoplasmic reticulum in physiology and pathology

Taurine is a sulfur-containing amino acid found in many cell organelles that plays a wide range of biological roles, including bile salt production, osmoregulation, oxidative stress reduction, and neuromodulation. Taurine treatments have also been shown to ameliorate the onset and development of many diseases, including hypertension, fatty liver, neurodegenerative diseases and ischemia-reperfusion injury, by exerting antioxidant, anti-inflammatory, and antiapoptotic effects. The endoplasmic reticulum (ER) is a dynamic organelle involved in a wide range of cellular functions, including lipid metabolism, calcium storage and protein stabilization. Under stress, the disruption of the ER environment leads to the accumulation of misfolded proteins and a characteristic stress response called the unfolded protein response (UPR). The UPR protects cells from stress and helps to restore cellular homeostasis, but its activation promotes cell death under prolonged ER stress. Recent studies have shown that ER stress is closely related to the onset and development of many diseases. This article reviews the beneficial effects and related mechanisms of taurine by regulating the ER in different physiological and pathological states, with the aim of providing a reference for further research and clinical applications.

The role of anesthesia in peri‑operative neurocognitive disorders: Molecular mechanisms and preventive strategies

Peri-operative neurocognitive disorders (PNDs) include postoperative delirium (POD) and postoperative cognitive dysfunction (POCD). Children and the elderly are the two populations most vulnerable to the development of POD and POCD, which results in both high morbidity and mortality. There are many factors, including neuroinflammation and oxidative stress, that are associated with POD and POCD. General anesthesia is a major risk factor of PNDs. However, the molecular mechanisms of PNDs are poorly understood. Dexmedetomidine (DEX) is a useful sedative agent with analgesic properties, which significantly improves POCD in elderly patients. In this review, the current understanding of anesthesia in PNDs and the protective effects of DEX are summarized, and the underlying mechanisms are further discussed.

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

Purpose

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

Patients and Methods

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

Results

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

Conclusion

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

Role of Memantine in Limiting Cochleotoxicity in Rats

Οur aim was to test whether amikacin's well-known cochleotoxic effects could be suppressed, depending on whether an NMDA-antagonist (memantine) was administered simultaneously with or after amikacin treatment. Forty Wistar rats were used in this experiment. Ten rats acted as controls and received no medication (group A). Amikacin (200 mg/kg) was administered intraperitoneally (i.p.) once daily for 14 days to 10 animals in group B; amikacin (200 mg/kg) was administered concurrently with memantine (10 mg/kg, i.p., once daily) to the same 10 animals in group C. Group D was given intraperitoneal memantine (10 mg/kg, once daily) for 14 days following a 2-week amikacin treatment. The cochlear activity of the right ear was tested using DPOAE in conscious animals. All animals were sacrificed at the conclusion of the experiment and both cochleae were collected for histological and immunohistochemical analysis. All groups treated with amikacin showed decreased cochlear activity, as testified by decreased DPOAE-amplitudes compared to the pre-treatment state. In the rats of group B, the DPOAE reduction was more pronounced. On histologic exam, the cochlear structures of group C rats and, although to a lesser extent, group D rats showed less severe cochlea damage. Memantine plays a protective role, resulting in restoring partially cochlear structures when administered either simultaneously with or after completion of amikacin i.p. treatment in rats.

Brain N -acetyl-aspartyl-glutamate is associated with cognitive function in older virally suppressed people with HIV

OBJECTIVES

Cognitive impairment persists in virally suppressed people with HIV (VS-PWH) especially in higher order domains. One cortical circuit, linked to these domains, is regulated by N -acetyl-aspartyl glutamate (NAAG), the endogenous agonist of the metabotropic glutamate receptor 3. The enzyme glutamate carboxypeptidase II (GCPII) catabolizes NAAG and is upregulated in aging and disease. Inhibition of GCPII increases brain NAAG and improves learning and memory in rodent and primate models.

DESIGN

As higher order cognitive impairment is present in VS-PWH, and NAAG has not been investigated in earlier magnetic resonance spectroscopy studies (MRS), we investigated if brain NAAG levels measured by MRS were associated with cognitive function.

METHODS

We conducted a retrospective analysis of 7-Tesla MRS data from a previously published study on cognition in older VS-PWH. The original study did not separately quantify NAAG, therefore, work for this report focused on relationships between regional NAAG levels in frontal white matter (FWM), left hippocampus, left basal ganglia and domain-specific cognitive performance in 40 VS-PWH after adjusting for confounds. Participants were older than 50 years, negative for affective and neurologic disorders, and had no prior 3-month psychoactive-substance use.

RESULTS

Higher NAAG levels in FWM were associated with better attention/working memory. Higher left basal ganglia NAAG related to better verbal fluency. There was a positive relationship between hippocampal NAAG and executive function which lost significance after correction for confounds.

CONCLUSION

These data suggest brain NAAG serves as a biomarker of cognition in VS-PWH. Pharmacological modulation of brain NAAG warrants investigation as a therapeutic approach for cognitive deficits in VS-PWH.

Advances in foetal anaesthesia

Nowadays, widespread antenatal ultrasound screenings detect congenital anomalies earlier and more frequently. This has sparked research into foetal surgery, offering treatment options for various conditions. These surgeries aim to correct anomalies or halt disease progression until after birth. Minimally invasive procedures can be conducted under local anaesthesia (with/without maternal sedation), while open mid-gestational procedures necessitate general anaesthesia. Anaesthesia serves to prevent maternal and foetal pain, to provide immobilization, and to optimize surgical conditions by ensuring uterine relaxation. As early as 12 weeks after conception, the foetus may experience pain. Thus, in procedures involving innervated foetal tissue or requiring foetal immobilization, anaesthetic drugs can be administered directly to the foetus (intramuscular or intravenous) or indirectly (transplacental) to the mother. However, animal studies have indicated that exposure to prenatal anaesthesia might impact foetal brain development, translating these findings to the clinical setting remains difficult.

Acupuncture Alleviates Chronic Ischemic White Matter Injury in SHR Rats via JNK-NMDAR Circuit

To study the protective mechanism of acupuncture at "Jiangya Recipe" on chronic ischemic white matter injury in spontaneously hypertensive rats (SHR) and the regulation of Jun N-terminal kinase-N-methyl-D-aspartate receptor (JNK-NMDAR) loop. A hypertensive white matter injury model was established in 46 male SHR rats aged 11 weeks by bilateral common carotid artery tapering (SHR-2VGO). In the SHR sham operation group, only bilateral common carotid arteries were isolated and in the SHR-2VGO modeling group, 36 rats were used for microcoil spring clip implantation to narrow the common carotid arteries and then, after 2 weeks of modeling, rats with impaired motor function were removed, and SHR-2VGO rats with successful final models were randomly divided into the model group, JNK blocking group, and acupuncture group. The sham operation group, model group, and JNK blocking group underwent the same grasping fixation, and the acupuncture group received acupuncture at acupoints "Jiangya Fang" once daily. In the JNK blocker group, an injection cannula was implanted into the lateral ventricle and sp600125 was injected into the lateral ventricle at 4.5 ul/day for 4 weeks. One week after the end of the intervention, white matter lesions were detected by MRI DWI and T2 imaging, and the learning and memory ability of rats was tested by Y-Maze and Passive Avoidance. Myelin density was detected by luxol fast blue (LFB) staining, also axon arrangement, myelin integrity, and thickness of neurons were detected by electron microscopy; neuronal morphology and the number of Nissl bodies in the hippocampus were detected by Nissl staining, dendritic spine density changes were detected by Golgi staining, and JNK, NMDAR1, and N-methyl-D-receptor 2B (NMDAR2B) in DG, CA3 region of hippocampus were detected by immunohistochemistry, protein expression of p-JNK/JNK, p-NMDAR1/NMDAR1, NMDAR2B, GSK3β protein expression in the fimbria of hippocampus was detected by Western blot. The Y maze test of SHR-2VGO+Acu and SHR-2VGO+ sp600125 group showed that the spontaneous alternating reaction rate increased significantly. At the same time, the incubation period increased significantly and the number of errors decreased significantly in Passive Avoidance. MRI T2WI showed that the white matter high signal of the corpus callosum, internal capsule and hippocampal fimbria in the SHR-2VGO+ sp600125 and SHR-2VGO+Acu groups was significantly lower than that in the SHR-2VGO model group, and the striatum and anterior commissure were not obvious. DWI showed that the SHR-2VGO model group had scattered high signal and limited diffusion movement in both the internal capsule and striatum, but the difference between groups was not obvious. Compared with SHR-2VGO rats, LFB staining of SHR-2VGO + sp600125 and SHR-2VGO +Acu groups showed significant relaxation of myelin porosity in corpus callosum, striatum, inner capsule, anterior commissure and hippocampal fimbria, and electron microscopy showed improved axonal myelin integrity and thickness in corpus callosum region. Also, the number of blue patchy Nissl bodies increased, and the number and complexity of dendritic spines increased significantly in Golgi staining. Immunohistochemical detection showed that JNK levels in DG and CA3 region were increased and NMDAR1 and NMDAR2B levels were decreased in SHR-2VGO+Acu and SHR-2VGO+ sp600125 groups. Meanwhile, protein expressions of GSK3β, NMDAR1/p-NMDAR1 and NMDAR2B in fimbria of hippocampus were increased, and JNK/P-JNK protein expression decreased. Acupuncture can increase the density and thickness of myelin sheath in white matter areas of corpus callosum, anterior commissure and hippocampal fimbria, increase the number and length of hippocampal neuronal dendrites, and improve hypertensive white matter injury and cognitive decline through JNK-NMDAR pathway.

Neurodevelopment of children exposed to prolonged anesthesia in infancy: GABA study interim analysis of resting-state brain networks at 2, 4, and 10-months old

BACKGROUND

Previous studies have raised concerns regarding neurodevelopmental impacts of early exposures to general anesthesia and surgery. Electroencephalography (EEG) can be used to study ontogeny of brain networks during infancy. As a substudy of an ongoing study, we examined measures of functional connectivity in awake infants with prior early and prolonged anesthetic exposures and in control infants.

METHODS

EEG functional connectivity was assessed using debiased weighted phase lag index at source and sensor levels and graph theoretical measures for resting state activity in awake infants in the early anesthesia (n = 26 at 10 month visit, median duration of anesthesia = 4 [2, 7 h]) and control (n = 38 at 10 month visit) groups at ages approximately 2, 4 and 10 months. Theta and low alpha frequency bands were of primary interest. Linear mixed models incorporated impact of age and cumulative hours of general anesthesia exposure.

RESULTS

Models showed no significant impact of cumulative hours of general anesthesia exposure on debiased weighted phase lag index, characteristic path length, clustering coefficient or small-worldness (conditional R2 0.05-0.34). An effect of age was apparent in many of these measures.

CONCLUSIONS

We could not demonstrate significant impact of general anesthesia in the first months of life on early development of resting state brain networks over the first postnatal year. Future studies will explore these networks as these infants grow older.

Neurosteroids and their potential as a safer class of general anesthetics

Neurosteroids (NS) are a class of steroids that are synthesized within the central nervous system (CNS). Various NS can either enhance or inhibit CNS excitability and they play important biological roles in brain development, brain function and as mediators of mood. One class of NS, 3α-hydroxy-pregnane steroids such as allopregnanolone (AlloP) or pregnanolone (Preg), inhibits neuronal excitability; these endogenous NS and their analogues have been therapeutically applied as anti-depressants, anti-epileptics and general anesthetics. While NS have many favorable properties as anesthetics (e.g. rapid onset, rapid recovery, minimal cardiorespiratory depression, neuroprotection), they are not currently in clinical use, largely due to problems with formulation. Recent advances in understanding NS mechanisms of action and improved formulations have rekindled interest in development of NS as sedatives and anesthetics. In this review, the synthesis of NS, and their mechanism of action will be reviewed with specific emphasis on their binding sites and actions on γ-aminobutyric acid type A (GABAA) receptors. The potential advantages of NS analogues as sedative and anesthetic agents will be discussed.

The role of NMDARs in the anesthetic and antidepressant effects of ketamine

BACKGROUND

As a phencyclidine (PCP) analog, ketamine can generate rapid-onset and substantial anesthetic effects. Contrary to traditional anesthetics, ketamine is a dissociative anesthetic and can induce loss of consciousness in patients. Recently, the subanaesthetic dose of ketamine was found to produce rapid-onset and lasting antidepressant effects.

AIM

However, how different concentrations of ketamine can induce diverse actions remains unclear. Furthermore, the molecular mechanisms underlying the NMDAR-mediated anesthetic and antidepressant effects of ketamine are not fully understood.

METHOD

In this review, we have introduced ketamine and its metabolism, summarized recent advances in the molecular mechanisms underlying NMDAR inhibition in the anesthetic and antidepressant effects of ketamine, explored the possible functions of NMDAR subunits in the effects of ketamine, and discussed the future directions of ketamine-based anesthetic and antidepressant drugs.

RESULT

Both the anesthetic and antidepressant effects of ketamine were thought to be mediated by N-methyl-D-aspartate receptor (NMDAR) inhibition.

CONCLUSION

The roles of NMDARs have been extensively studied in the anaesthetic effects of ketamine. However, the roles of NMDARs in antidepressant effects of ketamine are complicated and controversial.

Global Trends and Hotspots in Pediatric Anesthetic Neurotoxicity Research: A Bibliometric Analysis From 2000 to 2023

The impact of general anesthetics on brain function development is one of the top frontier issues of public concern. However, little bibliometric analysis has investigated this territory systematically. Our study aimed to visualize the publications between 2000 and 2023 to inspire the trends and hotspots in anesthetic neurodevelopmental toxicity research. Publications from 2000 to 2023 were collected from the Web of Science Core Collection. CiteSpace was utilized to plot and analyze the network maps of countries, institutions, authors, journals, and keywords associated with these publications. A total of 864 publications, consisting of 786 original articles and 78 reviews, were extracted from 2000 to 2023. The annual publications have increased constantly over the past two decades. The USA and the People's Republic of China were the leading driving forces in this field. Harvard University was the most productive institution. Zhang Y published the most related articles, and Jevtovic-Todorovic V was mostly cited in this field. The most prolific journal was Pediatric Anesthesia, and the most frequently co-cited journal was Anesthesiology. Keywords were divided into nine clusters: "apoptosis", "propofol", "developing brain", "cognitive dysfunction", "neuronal cell degeneration", "brain", "neuroinflammation", "local anesthesia", and "oxygen therapy". The strongest citation bursts in earlier years were "learning disability", "cell death", and "cognitive function". The emerging trends in the coming years were "awake regional anesthesia", "behavioral outcome", and "infancy general anesthesia compared to spinal anesthesia". We conclude that anesthetic-induced neurotoxicity has received growing attention in the past two decades. Our findings evaluated the present status and research trends in this area, which may provide help for exploring further potential prospects on hot topics and frontiers.

The impact of general anesthesia on the outcomes of preterm infants with gestational age less than 32 weeks delivered via cesarean section

Background

Recent advancements in China's perinatal and neonatal intensive care have significantly reduced neonatal mortality, yet preterm births before 32 weeks remain the primary cause of neonatal fatalities and contribute to long-term disabilities. The prognosis of very preterm infants (VPIs) is significantly affected by factors including the intrauterine environment, delivery method and neonatal intensive care. Cesarean section which often used for preterm births has implications that are not fully understood, particularly concerning the type of anesthesia used. This study examines the impact of general anesthesia (GA) during cesarean delivery on VPI outcomes, aiming to identify strategies for mitigating GA-associated risks.

Methods

This cohort study analyzed 1,029 VPIs born via cesarean section under 32 weeks' gestation at our single-center from 1 January 2018, to 31 December 2022. Detailed medical records, encompassing perioperative information, maternal data and neonatal outcomes were meticulously examined. The primary aim of this investigation was to compare maternal characteristics and neonatal outcomes between VPIs delivered under GA and neuraxial anesthesia (NA). A significance level of p < 0.05 was established.

Results

Of the 1,029 VPIs analyzed, 87.95% (n = 905) were delivered via NA and 12.05% (n = 124) via GA. Mothers with hypertensive pregnancy diseases and emergency operations were more inclined to choose GA. VPIs delivered under GA showed a lower Apgar score at one and 5 minutes (p < 0.01), increased need for tracheal intubation resuscitation (32.2% vs. 12.2%, p < 0.01) and a greater incidence of severe neurological injury (SNI) (14.5% vs. 5%, p < 0.01). Multivariable analysis revealed GA was significantly associated with lower Apgar scores at one (OR 6.321, 95% CI 3.729-10.714; p < 0.01) and 5 minutes (OR 4.535, 95% CI 2.975-6.913; p < 0.01), higher risk of tracheal intubation resuscitation (OR = 3.133, 95% CI = 1.939-5.061; p < 0.01) and SNI (OR = 3.019, 95% CI = 1.615-5.643; p < 0.01). Furthermore, for VPIs delivered under GA, a prolonged interval from skin incision to fetus delivery was associated with a lower 5-min Apgar score (p < 0.01).

Conclusion

This study revealed the significant impact of GA on adverse outcomes among VPIs. In cases when GA is required, proactive measures should be instituted for the care of VPIs such as expediting the interval from skin incision to fetal delivery.

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.

Memantine: Updating a rare success story in pro-cognitive therapeutics

The great potential for NMDA receptor modulators as druggable targets in neurodegenerative disorders has been met with limited success. Considered one of the rare exceptions, memantine has consistently demonstrated restorative and prophylactic properties in many AD models. In clinical trials memantine slows the decline in cognitive performance associated with AD. Here, we provide an overview of the basic properties including pharmacological targets, toxicology and cellular effects of memantine. Evidence demonstrating reductions in molecular, physiological and behavioural indices of AD-like impairments associated with memantine treatment are also discussed. This represents both an extension and homage to Dr. Chris Parson's considerable contributions to our fundamental understanding of a success story in the AD treatment landscape.

Antenatal Magnesium Sulfate Benefits Female Preterm Infants but Results in Poor Male Outcomes

Magnesium sulfate (MagSul) is used clinically to prevent eclamptic seizures during pregnancy and as a tocolytic for preterm labor. More recently, it has been implicated as offering neural protection in utero for at-risk infants. However, evidence is mixed. Some studies found that MagSul reduced the incidence of cerebral palsy (CP) but did not improve other measures of neurologic function. Others did not find any improvement in outcomes. Inconsistencies in the literature may reflect the fact that sex effects are largely ignored, despite evidence that MagSul shows sex effects in animal models of neonatal brain injury. The current study used retrospective infant data to assess differences in developmental outcomes as a function of sex and MagSul treatment. We found that on 18-month neurodevelopmental cognitive and language measures, preterm males treated with MagSul (n = 209) had significantly worse scores than their untreated counterparts (n = 135; p < 0.05). Female preterm infants treated with MagSul (n = 220), on the other hand, showed a cognitive benefit relative to untreated females (n = 123; p < 0.05). No significant effects of MagSul were seen among females on language (p > 0.05). These results have tremendous implications for risk-benefit considerations in the ongoing use of MagSul and may explain why benefits have been hard to identify in clinical trials when sex is not considered.

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

Objectives

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

Methods

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

Results

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

Conclusions

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

Genetic Counseling of Fetal Microcephaly

Fetal microcephaly is a small head with various losses of cerebral cortical volume. The affected cases may suffer from a wide range in severity of impaired cerebral development from slight to severe mental retardation. It can be an isolated finding or with other anomalies depending on the heterogeneous causes including genetic mutations, chromosomal abnormalities, congenital infectious diseases, maternal alcohol consumption, and metabolic disorders during pregnancy. It is often a lifelong and incurable condition. Thus, early detection of fetal microcephaly and identification of the underlying causes are important for clinical staff to provide appropriate genetic counseling to the parents and accurate management.

Anaesthesia-induced Changes in Genomic Expression Leading to Neurodegeneration

General anaesthetics (GA) have been in continuous clinical use for more than 170 years, with millions of young and elderly populations exposed to GA to relieve perioperative discomfort and carry out invasive examinations. Preclinical studies have shown that neonatal rodents with acute and chronic exposure to GA suffer from memory and learning deficits, likely due to an imbalance between excitatory and inhibitory neurotransmitters, which has been linked to neurodevelopmental disorders. However, the mechanisms behind anaesthesia-induced alterations in late postnatal mice have yet to be established. In this narrative review, we present the current state of knowledge on early life anaesthesia exposure-mediated alterations of genetic expression, focusing on insights gathered on propofol, ketamine, and isoflurane, as well as the relationship between network effects and subsequent biochemical changes that lead to long-term neurocognitive abnormalities. Our review provides strong evidence and a clear picture of anaesthetic agents' pathological events and associated transcriptional changes, which will provide new insights for researchers to elucidate the core ideas and gain an in-depth understanding of molecular and genetic mechanisms. These findings are also helpful in generating more evidence for understanding the exacerbated neuropathology, impaired cognition, and LTP due to acute and chronic exposure to anaesthetics, which will be beneficial for the prevention and treatment of many diseases, such as Alzheimer's disease. Given the many procedures in medical practice that require continuous or multiple exposures to anaesthetics, our review will provide great insight into the possible adverse impact of these substances on the human brain and cognition.

The role of neurotransmitters in glioblastoma multiforme-associated seizures

GBM, or glioblastoma multiforme, is a brain tumor that poses a great threat to both children and adults, being the primary cause of death related to brain tumors. GBM is often associated with epilepsy, which can be debilitating. Seizures and the development of epilepsy are the primary symptoms that have a severe impact on the quality of life for GBM patients. It is increasingly apparent that the nervous system plays an essential role in the tumor microenvironment for all cancer types, including GBM. In recent years, there has been a growing understanding of how neurotransmitters control the progression of gliomas. Evidence suggests that neurotransmitters and neuromodulators found in the tumor microenvironment play crucial roles in the excitability, proliferation, quiescence, and differentiation of neurons, glial cells, and neural stem cells. The involvement of neurotransmitters appears to play a significant role in various stages of GBM. In this review, the focus is on presenting updated knowledge and emerging ideas regarding the interplay between neurotransmitters and neuromodulators, such as glutamate, GABA, norepinephrine, dopamine, serotonin, adenosine, and their relationship with GBM and the seizures induced by this condition. The review aims to explore the current understanding and provide new insights into the complex interactions between these neurotransmitters and neuromodulators in the context of GBM-related seizures.

The bibliometric analysis of most cited 100 papers in anesthesia-induced neurotoxicity

Anesthesia-induced neurotoxicity is a major concern for anesthetists for more than 20 years. Many experimental and clinical studies have been conducted on this topic since late 1990s. However, bibliometric analysis of these papers has not been reported. In this study, we aimed to analyze the 100 most cited articles on anesthesia-induced neurotoxicity. It was planned as cross-sectional study. On January 30, 2023, we searched the "Web of Science (WOS)" database for anesthesia-induced neurotoxicity and most cited 100 papers about this topic were obtained. Data such as authors' names, year of publication, name of the journal, type of paper, and citation numbers were analyzed. The most cited 100 papers were read by the investigators, and the anesthetic, animal type in experimental studies, any protective agent and the method for detecting neurotoxicity used in the studies were also noted. There were 75 articles and 22 reviews in the 100 most cited articles. We found that most of the papers in most cited 100 list were published between 2010 to 1024. Most of the papers (11%) were from Harvard University and almost half of the papers (49%) were published in Anesthesiology. A great number of studies were performed in newborns or early childhood (85.5%) and inhalational anesthetics (54.7%) were the most studied anesthetic type. Most of the most cited 100 papers were published in Q1 journals (P = .012) and the continent of the most journals in this list was America (P = .014). The median total and annual citation numbers of funded papers were statistically significantly higher (P < .001 and P < .001 respectively). Anesthesia-induced neurotoxicity is very important, especially for pediatric anesthetists. This study is the first to conduct a bibliometric analysis of the most cited 100 publications on this field. Although there was a gap in the publications about this topic during COVID-19 pandemic, we believe that there will be many more publications on anesthesia-induced neurotoxicity since the mechanism, outcome and possible protection are still unknown.

Activation of N-Methyl-D-aspartate receptor contributed to the ultrasonic modulation of neurons in vitro

Ultrasound stimulation is increasingly used to investigate brain function and treat brain diseases due to its high level of safety and precise spatiotemporal resolution. Therefore, it is crucial to understand the underlying mechanisms involved in ultrasound brain stimulation. In this study, we investigate the role of NMDA receptors in mediating the effects of ultrasound on primary hippocampal neurons in mice. Our results show that ultrasound alone can activate heterologous NMDA receptor subunits, including NR1A, NR2A, and NR2B, in 293T cells, as well as endogenous NMDA receptors in primary neurons. This activation leads to an influx of calcium and an increase in nuclear c-Fos expression in primary neurons that have not been pre-treated with an NMDA receptor inhibitor. In conclusion, our findings demonstrate that NMDA receptors contribute to neuronal activation by ultrasound stimulation in vitro, providing insight into the molecular mechanisms of ultrasound neuromodulation and a new mediator for the sonogenetics technique.

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.

Whole-brain characterization of apoptosis after sevoflurane anesthesia reveals neuronal cell death patterns in the mouse neonatal neocortex

In the last two decades, safety concerns about general anesthesia (GA) arose from studies documenting brain cell death in various pharmacological conditions and animal models. Nowadays, a thorough characterization of sevoflurane-induced apoptosis in the entire neonatal mouse brain would help identify and further focus on underlying mechanisms. We performed whole-brain mapping of sevoflurane-induced apoptosis in post-natal day (P) 7 mice using tissue clearing and immunohistochemistry. We found an anatomically heterogenous increase in cleaved-caspase-3 staining. The use of a novel P7 brain atlas showed that the neocortex was the most affected area, followed by the striatum and the metencephalon. Histological characterization in cortical slices determined that post-mitotic neurons were the most affected cell type and followed inter- and intracortical gradients with maximal apoptosis in the superficial layers of the posterodorsal cortex. The unbiased anatomical mapping used here allowed us to confirm sevoflurane-induced apoptosis in the perinatal period, neocortical involvement, and indicated striatal and metencephalic damage while suggesting moderate hippocampal one. The identification of neocortical gradients is consistent with a maturity-dependent mechanism. Further research could then focus on the interference of sevoflurane with neuronal migration and survival during development.

Pain and neurodevelopmental outcomes of infants born very preterm

AIM

To investigate the impact of the level of pain experienced by infants born preterm on neurodevelopmental outcomes during their stay in a neonatal intensive care unit.

METHOD

In this retrospective data analysis we included all surviving infants born preterm with a gestational age between 23 and 32 weeks from 2011 to 2015, who were assessed using the Neonatal Pain, Agitation, and Sedation Scale and examined at 1 year of age using the Bayley Scales of Infant Development. We excluded all infants who had suffered severe neurological morbidities and undergone surgical interventions.

RESULTS

A total of 196 infants born preterm were included in the analyses: 105 in the 'no pain group' and 91 in the 'pain group'. Significant differences between the groups were detected for both mental and motor development (p = 0.003, 95% confidence interval [CI] 2.23-10.92; p = 0.025, 95% CI 0.64-9.78). The results remained significant after controlling for other important medical conditions (p = 0.001, 95% CI -19.65 to -5.40; p = 0.010, 95% CI -16.18 to -2.29).

INTERPRETATION

Neonatal pain exposure was associated with altered neurodevelopmental outcomes of infants born very preterm at a corrected age of 12 months. This observation highlights the importance of adequate pain management to reduce the risk of poor neurodevelopmental outcomes in these vulnerable patients.

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.