Maternal sevoflurane exposure affects differentiation of hippocampal neural stem cells by regulating miR-410-3p and ATN1

Angelicin Alleviates Maternal Isoflurane Exposure-Induced Offspring Cognitive Defects Through the Carbonic Anhydrase 4/Aquaporin-4 Pathway

An increasing number of studies reveal the deleterious effects of isoflurane (Iso) exposure during pregnancy on offspring cognition. However, no effective therapeutic strategy for Iso-induced deleterious effects has been well developed. Angelicin exerts an anti-inflammatory effect on neurons and glial cells. This study investigated the roles and mechanism of action of angelicin in Iso-induced neurotoxicity in vitro and in vivo. After exposing C57BL/6 J mice on embryonic day 15 (E15) to Iso for 3 and 6 h, respectively, neonatal mice on embryonic day 18 (E18) displayed obvious anesthetic neurotoxicity, which was revealed by the elevation of cerebral inflammatory factors and blood-brain barrier (BBB) permeability and cognitive dysfunction in mice. Angelicin treatment could not only significantly reduce the Iso-induced embryonic inflammation and BBB disruption but also improve the cognitive dysfunction of offspring mice. Iso exposure resulted in an increase of carbonic anhydrase (CA) 4 and aquaporin-4 (AQP4) expression at both mRNA and protein levels in vascular endothelial cells and mouse brain tissue collected from neonatal mice on E18. Remarkably, the Iso-induced upregulation of CA4 and AQP4 expression could be partially reversed by angelicin treatment. Moreover, GSK1016790A, an AQP4 agonist, was used to confirm the role of AQP4 in the protective effect of angelicin. Results showed that GSK1016790A abolished the therapeutic effect of angelicin on Iso-induced inflammation and BBB disruption in the embryonic brain and on the cognitive function of offspring mice. In conclusion, angelicin may serve as a potential therapeutic for Iso-induced neurotoxicity in neonatal mice by regulating the CA4/AQP4 pathway.

Multiple sevoflurane exposures during mid-trimester induce neurotoxicity in the developing brain initiated by 15LO2-Mediated ferroptosis

AIMS

Mid-gestational sevoflurane exposure may induce notable long-term neurocognitive impairment in offspring. This study was designed to investigate the role and potential mechanism of ferroptosis in developmental neurotoxicity induced by sevoflurane in the second trimester.

METHODS

Pregnant rats on day 13 of gestation (G13) were treated with or without 3.0% sevoflurane, Ferrostatin-1 (Fer-1), PD146176, or Ku55933 on three consecutive days. Mitochondrial morphology, ferroptosis-relative proteins, malondialdehyde (MDA) levels, total iron content, and glutathione peroxidase 4 (GPX4) activities were measured. Hippocampal neuronal development in offspring was also examined. Subsequently, 15-lipoxygenase 2 (15LO2)-phosphatidylethanolamine binding protein 1 (PEBP1) interaction and expression of Ataxia telangiectasia mutated (ATM) and its downstream proteins were also detected. Furthermore, Morris water maze (MWM) and Nissl's staining were applied to estimate the long-term neurotoxic effects of sevoflurane.

RESULTS

Ferroptosis mitochondria were observed after maternal sevoflurane exposures. Sevoflurane elevated MDA and iron levels while inhibiting GPX4 activity, and resultant long-term learning and memory dysfunction, which were alleviated by Fer-1, PD146176, and Ku55933. Sevoflurane could enhance 15LO2-PEBP1 interaction and activate ATM and its downstream P53/SAT1 pathway, which might be attributed to excessive p-ATM nuclear translocation.

CONCLUSION

This study proposes that 15LO2-mediated ferroptosis might contribute to neurotoxicity induced by maternal sevoflurane anesthesia during the mid-trimester in the offspring and its mechanism may be ascribed to hyperactivation of ATM and enhancement of 15LO2-PEBP1 interaction, indicating a potential therapeutic target for ameliorating sevoflurane-induced neurotoxicity.

Effect of epigenetic activating of Dlk1-Dio3 imprinted cluster on miR-370 expression due to folate deficiency during nerve development

Proper Dlk1-Dio3 imprinting plays a critical role in embryogenesis, and folic acid deficiency may affect the imprinting of this locus through epigenetic regulation. However, whether and how folic acid directly impacts the imprinting status of Dlk1-Dio3 to affect neural development remain unclear. Here, we found decreased IG-DMR (intergenic -differentially methylated regions) methylation in the folate-deficient encephalocele in humans, suggesting that abnormal Dlk1-Dio3 imprinting status is related to neural tube defects (NTDs) caused by folate deficiency. Similar results were obtained with folate-deficient embryonic stem cells. By miRNA chip analysis, folic acid deficiency led to changes in multiple miRNAs, including the upregulation of 15 miRNAs located in the Dlk1-Dio3 locus. Real-time PCR confirmed that seven of these miRNAs were upregulated, especially miR-370. In contrast to normal embryonic development, in which expression of miR-370 is highest at E9.5, the abnormally high and sustained expression of miRNA-370 in folate-deficient E13.5 embryos may contribute to NTDs. In addition, we found that DNMT3A (de novo DNA methyltransferases 3A) is a direct target gene of miR-370 in neural cells, and DNMT3A participates in the role of miR-370 in inhibiting cell migration. Finally, in the folate-deficient mouse model, Dlk1-Dio3 epigenetic activation was found in fetal brain tissue, along with the upregulation of miR-370 and the downregulation of DNMT3A. Collectively, our findings demonstrate a pivotal role of folate in the epigenetic regulation of Dlk1-Dio3 imprinting during neurogenesis, revealing an elegant mechanism for the activation of Dlk1-Dio3 locus miRNAs in folic acid deficiency.

Atrophin-1 Function and Dysfunction in Dentatorubral-Pallidoluysian Atrophy

Dentatorubral-pallidoluysian atrophy (DRPLA) is a rare, incurable genetic disease that belongs to the group of polyglutamine (polyQ) diseases. DRPLA is the most common in the Japanese population; however, its global prevalence is also increasing due to better clinical recognition. It is characterized by cerebellar ataxia, myoclonus, epilepsy, dementia, and chorea. DRPLA is caused by dynamic mutation of CAG repeat expansion in ATN1 gene encoding the atrophin-1 protein. In the cascade of molecular disturbances, the pathological form of atrophin-1 is the initial factor, which has not been precisely characterized so far. Reports indicate that DRPLA is associated with disrupted protein-protein interactions (in which an expanded polyQ tract plays a crucial role), as well as gene expression deregulation. There is a great need to design efficient therapy that would address the underlying neurodegenerative process and thus prevent or alleviate DRPLA symptoms. An in-depth understanding of the normal atrophin-1 function and mutant atrophin-1 dysfunction is crucial for this purpose. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

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.

Research progress on the effects and mechanisms of anesthetics on neural stem cells

Exposure to anesthetic drugs has been proven to seriously affect developing animals in terms of neural stem cells' (NSCs') proliferation, differentiation, and apoptosis. This can severely hamper the development of physiological learning and memory skills. Studies on the effects of anesthetics on NSCs' proliferation and differentiation are thus reviewed here, with the aim to highlight which specific drug mechanisms are the least harmful to NSCs. PubMed has been used as the preferential searching database of relevant literature to identify studies on the effects and mechanisms of NSCs' proliferation and differentiation. It was concluded that propofol and sevoflurane may be the safest options for NSCs during pregnancy and in pediatric clinical procedures, while dexmedetomidine has been found to reduce opioid-related damage in NSCs. It was also found that the growth environment may impact neurodevelopment even more than narcotic drugs. Nonetheless, the current scientific literature available further highlights how more extensive clinical trials are absolutely required for corroborating the conclusion drawn here.

MFG-E8 Exerts Neuroprotection in Neural Stem Cells Induced by Anesthetic Sevoflurane via Regulating the PI3K/AKT Pathways

MFG-E8 has shown tissue protection effects in various models of organ injury. In this study, the function of MFG-E8 in SEV-induced neural stem cells (NSCs) was studied. The cell viability and apoptosis affected by rhMFG-E8 were tested by MTT and flow cytometry analysis, respectively. Then, the mRNA expression of MFG-E8 was detected by qRT-PCR. The expression of SOD, GSF-Px, and MDA was assessed using ELISA assay. Western blot analysis was applied for assessing the expression of MFG-E8, BCL2, BAX, cleaved caspase-3, GRP-78, XBP-1, ATF-6, ATF-4, CHOP, p-PI3K, PI3K, p-AKT, and AKT. The pharmacological experiments suggested that both mRNA and protein expression of MFG-E8 were significantly decreased after 24 h, 48 h, and 72 h treatment with SEV, and the Western blot results displayed that 50 and 100 μg/ml rhMFG-E8 could evidently promote the expression of MFG-E8 in NSCs induced by SEV. Next, rhMFG-E8 reduced the apoptosis of NSCs induced by SEV through upregulating Bcl-2 and cleaved caspase-3 and downregulating Bax. Moreover, rhMFG-E8 alleviated the endoplasmic reticulum pressure of NSCs induced by SEV through decreasing the expression of GRP-78, XBP-1, ATF-6, ATF-4, and CHOP. In addition, the rhMFG-E8 could promote the expression of SOD and GSH-Px and inhibit the expression of MDA and LDH detected by the ELISA assay and LDH kit. Moreover, rhMFG-E8 elevated the expression of p-PI3K/PI3K and p-AKT/AKT, which were inhibited by SEV in NSCs. The results of this project supported that rhMFG-E8 protects neural activity in neural stem cells induced by anesthetic sevoflurane via regulating the PI3K/AKT pathways.

4.8% sevoflurane induces activation of autophagy in human neuroblastoma SH-SY5Y cells by the AMPK/mTOR signaling pathway

Prolonged sevoflurane exposure leads to neurotoxicity. Autophagy plays an important role in promoting cell survival in different conditions. However, the role and mechanism of autophagy in sevoflurane-induced neurotoxicity were not fully elucidated. We attempted to indicate whether sevoflurane could activate the AMP-activated protein kinase (AMPK)/mechanistic target of rapamycin (mTOR)-mediated autophagy to attenuate anesthetics-induced neuronal injury in this study. Sevoflurane treatment significantly decreased the cell viability and induced apoptosis of SH-SY5Y cells. The expression level of Bcl-2 decreased, while that of Bax remarkably increased. Meanwhile, autophagy was activated by sevoflurane exposure as evidenced by increased expression levels of autophagy-related proteins (LC3-II and Atg5), decreased expression level of autophagic substrate P62, and increased autophagosomes and autolysosomes. Further autophagosomes and fewer autolysosomes were observed in the presence of Bafilomycin A1, an autolysosomes degradation inhibitor, suggesting that sevoflurane induced autophagic flux rather than inhibiting degradation of autophagy. Activation of autophagy by rapamycin partly reversed the sevoflurane-decreased cell viability. In contrast, inhibition of autophagy by 3-Methyladenine (3-MA) or Atg5-targeted small interfering RNA (siRNA) aggravated the sevoflurane-induced neurotoxicity. Further examination revealed that sevoflurane-induced autophagy was mediated by the AMPK/mTOR signaling pathway, with increased p-AMPK expression and decreased p-mTOR expression. Collectively, these results indicated that sevoflurane activates autophagy by regulating the AMPK/mTOR signaling pathway, which is protective against sevoflurane-induced damage in SH-SY5Y cells. Our results may assist clinicians to develop further promising therapeutic strategies for the neurotoxicity induced by inhaled anesthetics.

Mechanistic insight into sevoflurane-associated developmental neurotoxicity

With the development of technology, more infants receive general anesthesia for surgery, other interventions, or clinical examination at an early stage after birth. However, whether general anesthetics can affect the function and structure of the developing infant brain remains an important, complex, and controversial issue. Sevoflurane is the most-used anesthetic in infants, but this drug is potentially neurotoxic. Short or single exposure to sevoflurane has a weak effect on cognitive function, while long or repeated exposure to general anesthetics may cause cognitive dysfunction. This review focuses on the mechanisms by which sevoflurane exposure during development may induce long-lasting undesirable effects on the brain. We review neural cell death, neural cell damage, impaired assembly and plasticity of neural circuits, tau phosphorylation, and neuroendocrine effects as important mechanisms for sevoflurane-induced developmental neurotoxicity. More advanced technologies and methods should be applied to determine the underlying mechanism(s) and guide prevention and treatment of sevoflurane-induced neurotoxicity.

1. We discuss the mechanisms underlying sevoflurane-induced developmental neurotoxicity from five perspectives: neural cell death, neural cell damage, assembly and plasticity of neural circuits, tau phosphorylation, and neuroendocrine effects. 2. Tau phosphorylation, IL-6, and mitochondrial dysfunction could interact with each other to cause a nerve damage loop. 3. miRNAs and lncRNAs are associated with sevoflurane-induced neurotoxicity.

Docosahexaenoic acid supplementation alleviates behavioral memory impairment caused via repeated administration of sevoflurane in aged rats

Elderly patients often need repeated surgical intervention, so it is important to determine the impact of repeated exposure to anesthetics on learning and memory. Docosahexaenoic acid (DHA) is considered to be an essential nutrient for maintaining brain health. The aim of the present study was to explore the potential effects of DHA on memory impairment induced by repeated sevoflurane anesthesia in aged rats. A total of 54 Sprague Dawley aged rats (18 months) were randomly divided into the following six groups: i) Control group; ii) sevoflurane group (Sev, 2.5% for 5 min); iii) DHA group (3 g/kg); iv) Sev + DHA (0.3 g/kg) group; v) Sev + DHA (1 g/kg) group; and vi) Sev + DHA (3 g/kg) group. Morris water maze experiment was performed to evaluate the learning and memory ability of the rats following treatment. H&E staining was used to observe any histological changes. Superoxide dismutase, malondialdehyde and glutathione peroxidase levels were detected using ELISA. Immunohistochemistry and western blotting were used to determine nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) protein expression levels. Following repeated sevoflurane anesthesia, rats exhibited a prolonged escape latency. The number of times rats crossed the platform and the time spent in the target quadrant were also significantly reduced by repeated sevoflurane anesthesia. However, rats treated with Sev + DHA exhibited a reduced escape latency, whilst the number of times they crossed the platform and the time spent in the target quadrant increased compared with Sev treatment alone. Histopathological examination revealed that DHA treatment ameliorated the disordered neuron arrangement, deep staining of the neuronal nucleus pyknosis and cell edema observed in the brain tissue induced by repeated sevoflurane anesthesia. Furthermore, the protein expression levels of Nrf2 and HO-1 were demonstrated to be significantly increased in rats treated with DHA and exposed to repeated sevoflurane anesthesia compared with those in untreated rats that underwent repeated sevoflurane anesthesia. In conclusion, the present study revealed that DHA exerted protective effects against impairments in learning and memory induced by repeated sevoflurane anesthesia in aged rats, which may be associated with the Nrf2/HO-1 signaling pathway.

Effects of Pregnancy Anesthesia on Fetal Nervous System

The effects of general anesthesia on the developing brain remain a great concern in the medical field and even in the public, and most researches in this area focus on infancy and childhood. In recent years, with the continuous development of medical technology, the number of operations during pregnancy is increasing, however, studies on general anesthesia during pregnancy are relatively lacking. The mid-trimester of pregnancy is a critical period, and is regarded as a safe period for surgery, but it is a fragile period for the development of the central nervous system and is particularly sensitive to the impact of the environment. Our research group found that general anesthesia may have adverse effects on fetal neurodevelopment during the mid-trimester. Therefore, in this review, we summarize the characteristics of anesthesia during pregnancy, and the related research of the anesthesia’s impacts on the development of central nervous system were introduced.