Propofol exposure in pregnant rats induces neurotoxicity and persistent learning deficit in the offspring

Suberoylanilide hydroxamic acid attenuates cognitive impairment in offspring caused by maternal surgery during mid-pregnancy

Some pregnant women have to experience non-obstetric surgery during pregnancy under general anesthesia. Our previous studies showed that maternal exposure to sevoflurane, isoflurane, propofol, and ketamine causes cognitive deficits in offspring. Histone acetylation has been implicated in synaptic plasticity. Propofol is commonly used in non-obstetric procedures on pregnant women. Previous studies in our laboratory showed that maternal propofol exposure in pregnancy impairs learning and memory in offspring by disturbing histone acetylation. The present study aims to investigate whether HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) could attenuate learning and memory deficits in offspring caused by maternal surgery under propofol anesthesia during mid-pregnancy. Maternal rats were exposed to propofol or underwent abdominal surgery under propofol anesthesia during middle pregnancy. The learning and memory abilities of the offspring rats were assessed using the Morris water maze (MWM) test. The protein levels of histone deacetylase 2 (HDAC2), phosphorylated cAMP response-element binding (p-CREB), brain-derived neurotrophic factor (BDNF), and phosphorylated tyrosine kinase B (p-TrkB) in the hippocampus of the offspring rats were evaluated by immunofluorescence staining and western blot. Hippocampal neuroapoptosis was detected by TUNEL staining. Our results showed that maternal propofol exposure during middle pregnancy impaired the water-maze learning and memory of the offspring rats, increased the protein level of HDAC2 and reduced the protein levels of p-CREB, BDNF and p-TrkB in the hippocampus of the offspring, and such effects were exacerbated by surgery. SAHA alleviated the cognitive dysfunction and rescued the changes in the protein levels of p-CREB, BDNF and p-TrkB induced by maternal propofol exposure alone or maternal propofol exposure plus surgery. Therefore, SAHA could be a potential and promising agent for treating the learning and memory deficits in offspring caused by maternal nonobstetric surgery under propofol anesthesia.

Anaesthesia and brain development: a review of propofol-induced neurotoxicity in pediatric populations

With the advancement of medical technology, there are increasing opportunities for new-borns, infants, and pregnant women to be exposed to general anaesthesia. Propofol is commonly used for the induction of anaesthesia, maintenance of general intravenous anaesthesia and sedation of intensive-care children. Many previous studies have found that propofol has organ-protective effects, but growing evidence suggests that propofol interferes with brain development, affecting learning and cognitive function. The purpose of this review is to summarize the latest progress in understanding the neurotoxicity of propofol. Evidence from case studies and clinical studies suggests that propofol has neurotoxicity on the developing brain. We classify the findings on propofol-induced neurotoxicity based on its damage mechanism. We end by summarizing the current protective strategies against propofol neurotoxicity. Fully understanding the neurotoxic mechanisms of propofol can help us use it at a reasonable dosage, reduce its side effects, and increase patient safety.

Determination of the embryotoxic effects of propofol injected into eggs on the cerebellum and spinal cord using histologic methods: an animal study

Background/aim

This study aims to determine the possible embryotoxic effects of propofol on the cerebellum and spinal cord using fertile chicken eggs.

Materials and methods

A total of 430 fertile eggs were divided into 5 groups: control, saline, 2.5 mg.kg-1, 12.5 mg.kg-1, and 37.5 mg.kg-1 propofol. Injections were made immediately before incubation via the air chamber. On the 15th, 18th, and 21st day of incubation, 6 embryos from each group were evaluated. Serial paraffin sections taken from the cerebellum and spinal cord were stained with hematoxylin-eosin, Kluver-Barrera, toluidine blue, and periodic acid-Schiff's reaction. The outer granular layer and total cortex thickness were measured, and the linear density of the Purkinje cells was determined. The ratios of the substantia grisea surface area to the total surface area of the spinal cord were calculated. The transverse and longitudinal diameters of the canalis centralis were also assessed.

Results

No structural malformation was observed in any embryos examined macroscopically. No significant difference was observed between the groups in terms of development and histologic organization of the cerebellum and spinal cord. However, on the 15th, 18th, and 21st day, the outer granular layer (p < 0.001 for all days) and the total cortex thickness (p < 0.01, p < 0.001, and p < 0.001, respectively) decreased significantly in different propofol dose groups in varying degrees in the cerebellum. Similarly, in the spinal cord, there were significant changes in the ratios of the substantia grisea surface area to the total surface area (p < 0.01 and p < 0.001, respectively).

Conclusion

It was concluded that the in-ovo-administered propofol given immediately before incubation has adverse effects on the developing cerebellum and spinal cord. Therefore, it is important for anesthesiologists always to remain vigilant when treating female patients of childbearing age.

Prenatal Sevoflurane Exposure Impairs the Learning and Memory of Rat Offspring via HMGB1-Induced NLRP3/ASC Inflammasome Activation

The neurotoxic effects of sevoflurane anesthesia on the immature nervous system have aroused public concern, but the specific effects and mechanism remain poorly understood. Pyroptosis caused by the activation of the NLRP3 inflammasome is pivotal for cell survival and acts as a key player in cognitive impairment. This study was carried out to determine the critical role of the NLRP3 inflammasome and high-mobility group box 1 (HMGB1) in sevoflurane-induced cognitive impairment. On gestational day 20 (G20), 3% sevoflurane was administered for 4 h to pregnant rats. The hippocampus and cerebral cortex of the offspring were harvested at postnatal day 1 (P1) for Western blotting and immunofluorescence staining. Pregnant rat sevoflurane exposure increased the protein levels of NLRP3, ASC, cleaved-caspase 1 (p20), mature-IL-1β (m-IL-1β), and HMGB1 in the cerebral cortex and hippocampus of offspring rats. More microglial cells of offspring were also observed after sevoflurane anesthesia. The Morris water maze (MWM) test was implemented to evaluate cognitive function from postnatal day 30 (P30) to postnatal 35 (P35) of offspring. The sevoflurane-treated offspring took longer than the control rats to find the MWM platform during the learning phase. Furthermore, they had a longer travel distance and less time in the target quadrant than the control rats in the probe trial. Maternal intraperitoneal injection of glycyrrhizin (an inhibitor of HMGB1) attenuated the sevoflurane-induced microglia and NLRP3/ASC inflammasome activation and cognitive impairment of offspring. Simultaneously, the sevoflurane-induced increase in Toll-like receptors (TLR4) and nuclear factor-κB (NF-κB) was significantly reduced by glycyrrhizin. We concluded that the HMGB1 inhibitor may repress the sevoflurane-induced activation of the NLRP3/ASC inflammasome and cognitive dysfunction and that TLR4/NF-κB signaling maybe the key pathway, at least in part.

Neurocognitive Effects of Fetal Exposure to Anesthesia

Surgery during pregnancy occurs when maternal or fetal needs outweigh the status quo, yet much uncertainty remains regarding the effects of anesthesia and surgery on fetal neurodevelopment. This article will review common maternal and fetal indications for invasive procedures, along with contemporary research on fetal neurodevelopment following anesthesia and surgery, focusing on future areas of investigation.

Analgesia for fetal pain during prenatal surgery: 10 years of progress

Some doubts on the necessity and safety of providing analgesia to the fetus during prenatal surgery were raised 10 years ago. They were related to four matters: fetal sleep due to neuroinhibitors in fetal blood, the immaturity of the cerebral cortex, safety, and the need for fetal direct analgesia. These objections now seem obsolete. This review shows that neuroinhibitors give fetuses at most some transient sedation, but not a complete analgesia, that the cerebral cortex is not indispensable to feel pain, when subcortical structures for pain perception are present, and that maternal anesthesia seems not sufficient to anesthetize the fetus. Current drugs used for maternal analgesia pass through the placenta only partially so that they cannot guarantee a sufficient analgesia to the fetus. Extraction indices, that is, how much each analgesic drug crosses the placenta, are provided here. We here report safety guidelines for fetal direct analgesia. In conclusion, the human fetus can feel pain when it undergoes surgical interventions and direct analgesia must be provided to it. IMPACT: Fetal pain is evident in the second half of pregnancy. Progress in the physiology of fetal pain, which is reviewed in this report, supports the notion that the fetus reacts to painful interventions during fetal surgery. Evidence here reported shows that it is an error to believe that the fetus is in a continuous and unchanging state of sedation and analgesia. Data are given that disclose that drugs used for maternal analgesia cross the placenta only partially, so that they cannot guarantee a sufficient analgesia to the fetus. Safety guidelines are given for fetal direct analgesia.

Prophylactic Melatonin Treatment Ameliorated Propofol-Induced Cognitive Dysfunction in Aged Rats

Considering the fact that melatonin acts as protective agent in various cognitive impairment, we decided to explore the precise effect of pretreatment with melatonin on cognitive function, mitochondrial activity, apoptosis and synaptic integrity in aged rats anesthetized by propofol. We first randomly allocated the thirty Sprague Dawley rats into three groups: Control vehicle-treated group (Con), Propofol-treated group (Pro) and Melatonin + Propofol group (Mel + Pro). The Barnes maze, open field and contextual fear conditioning test were employed to evaluate spatial memory, exploratory behavior and general locomotor activity, and hippocampus-dependent learning and memory ability, respectively. Moreover, mitochondrial function (including reactive oxygen species, mitochondrial membrane potential and ATP levels) and apoptosis were detected in the regions of hippocampus (HIP) and prefrontal cortex (PFC). The results of behavioral tests suggested that melatonin improved propofol-induced memory impairment in aged rats. Melatonin mitigated mitochondrial dysfunction and decreased the apoptotic cell counts in the regions of HIP and PFC. Furthermore, prophylactic melatonin treatment also reversed the propofol-induced inactivation of PKA/CREB/BDNF signaling and synaptic dysfunction. On the whole, our results indicated that melatonin ameliorated the propofol-induced cognitive disorders via attenuating mitochondrial dysfunction, apoptosis, inactivation of PKA/CREB/BDNF signaling and synaptic dysfunction.

Effects of Maternal Abdominal Surgery on Fetal Brain Development in the Rabbit Model

INTRODUCTION

Anesthesia during pregnancy can impair fetal neurodevelopment, but effects of surgery remain unknown. The aim is to investigate effects of abdominal surgery on fetal brain development. Hypothesis is that surgery impairs outcome.

METHODS

Pregnant rabbits were randomized at 28 days of gestation to 2 h of general anesthesia (sevoflurane group, n = 6) or to anesthesia plus laparoscopic appendectomy (surgery group, n = 13). On postnatal day 1, neurobehavior of pups was assessed and brains harvested. Primary outcome was neuron density in the frontal cortex, and secondary outcomes included neurobehavioral assessment and other histological parameters.

RESULTS

Fetal survival was lower in the surgery group: 54 versus 100% litters alive at birth (p = 0.0442). In alive litters, pup survival until harvesting was 50 versus 69% (p = 0.0352). No differences were observed for primary outcome (p = 0.5114) for surviving pups. Neuron densities were significantly lower in the surgery group in the caudate nucleus (p = 0.0180), but not different in other regions. No differences were observed for secondary outcomes. Conclusions did not change after adjustment for mortality.

CONCLUSION

Abdominal surgery in pregnant rabbits at a gestational age corresponding to the end of human second trimester results in limited neurohistological changes but not in neurobehavioral impairments. High intrauterine mortality limits translation to clinical scenario, where fetal mortality is close to zero.

MicroRNA-665 mediates propofol-induced cell apoptosis in human stem cell-derived neurons

We aimed to evaluate the neurotoxicity and mechanisms of anesthetics propofol in hESC-derived neurons. Cell apoptosis in hESC-derived neurons' exposure to 4, 10 and 20 μg/mL propofol for 6 h was assessed using terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick end labeling (TUNEL) staining and microRNA-665 (miR-665) expression was assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR). miR-665 was overexpressed and knocked down using a miR-665 mimic and anti-665 transfection, respectively. The results showed that hESCs exposed to propofol showed a dose-dependent cell apoptosis, followed by the upregulation of miR-665 expression. Overexpression of miR-665 increased propofol-induced apoptosis in hESC cells. And targeting miR-665 decreased propofol-induced cell apoptosis in hESC cells. These data suggest that propofol induces cell death in hESC-derived neurons and the propofol-induced cell apoptosis may occur via miR-665-dependent mechanism.

Effects of embryonic propofol exposure on axonal growth and locomotor activity in zebrafish

Prenatal propofol exposure induced neurotoxicity in the developing brains and led to persistent learning deficits in the offspring. Our goal was to use zebrafish to explore whether the decline in learning and memory was correlated with inhibition of neuronal growth after propofol exposure. Zebrafish embryos at 6 hours postfertilization (hpf) were exposed to control or 1, 2 or 4 μg/mL propofol until 48 hpf. Spontaneous locomotor activity and swimming behavior in response to dark-to-light photoperiod stimulation were studied in zebrafish larvae at 6 days postfertilization (dpf). The adaptability to repeated stimulation was used to indicate learning and memory function of larvae. Transgenic NBT line zebrafish was used to quantitate the effect of propofol on motor neuronal growth of embryos in vivo. Six dpf transgenic zebrafish larvae went through photoperiod stimulation after their neuronal length had been analyzed during the embryonic period. Our data indicate that embryonic exposure to 1, 2 and 4 μg/mL propofol had no adverse effect on spontaneous movement in zebrafish larvae, but 2 and 4 μg/mL propofol significantly impaired the learning and memory function of larvae. Moreover, propofol significantly inhibited axonal growth of motor neurons during the embryonic stage, which was correlated with learning and memory deficiency in larvae. Our findings demonstrate that the neuronal growth was correlated with learning and memory function, indicating the relevance of zebrafish as a new model to explore the mechanisms through which propofol induces long-term learning and memory impairment.

Inhibition of the electron transport chain in propofol induced neurotoxicity in zebrafish embryos

Fetal and neonatal exposure to propofol can lead to neuronal death and long-term neurobehavioral deficiencies in both rodents and nonhuman primates. Zebrafish embryo, which is fertilized ex-utero, has provided us a new model species to study the effects of general anesthetics on developing brain. Inhibited electron transport chain leads to mitochondrial dysfunction and insufficient energy production. The aim of this study was to dissect the role of electron transport chain in propofol-induced neurotoxicity. 6 h post fertilization (hpf) zebrafish embryos were exposed to control or 1, 2 or 4 μg/ml propofol until 48hpf. Acridine orange staining was used to assess cell apoptosis in the brain of zebrafish embryos. The activity of mitochondrial electron transport chain complex was assessed using colorimetric method. Expression of key subunit of cytochrome c oxidase was assessed by western blot and transcription level of cox4i1 was assessed by quantitative real time-PCR. The mitochondrial membrane potential and ATP content were assessed. Exposure to 1, 2 and 4 μg/ml propofol induced significant increases in cell apoptosis in the brain of zebrafish embryos in a dose-dependent manner and led to significant decreases in electron transport chain complex IV activity from (0.161 ± 0.023)μmol/mg/min in blank control-treated group to (0.096 ± 0.015)μmol/mg/min, (0.083 ± 0.013)μmol/mg/min and (0.045 ± 0.014)μmol/mg/min respectively, accompanied by decreased expression of key regulatory subunit of cytochrome c oxidase-subunit IV and decreased transcription level of cox4i1. Propofol exposure also decreased the mitochondrial membrane potential and ATP content. Our findings demonstrate that inhibition of the electron transport chain is involved in the mechanisms by which propofol induces neurotoxicity in the developing brain.

Effects of the application of general anesthesia with propofol during the early stage of pregnancy on brain development and function of SD rat offspring and the intervention of DHA

Objective: To investigate the effects of propofol used in early pregnancy on brain development and function of offspring, and further to explore the effects of docosahexaenoic acid (DHA) intervention. Methods: Forty pregnant rats were randomly divided into four groups: control group (C), propofol group (P), DHA intervention group (D), and propofol + DHA group (P + D). The DHA treatment was before propofol was administered. Morris water maze test was performed 30 days after delivery. The levels of amyloid beta (Aβ), IL-1β and reactive oxygen species (ROS) in hippocampus were detected by enzyme-linked immunosorbent assay (ELISA). The expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase-B (Trk-B), protein kinase B (Akt), p-Akt and cAMP response element-binding protein (CREB) in hippocampus were detected by western blot. Results: The learning and memory abilities of the rats in P group were reduced. The levels of Aβ, IL-1β and ROS were increased, while the levels of BDNF, Trk-B and CREB, and p-Akt/Akt ratio were reduced. In addition, compared with P group, DHA in P + D group reversed or alleviated adverse changes caused by propofol. Conclusions: Application of general anesthesia with propofol during the early stage of pregnancy can negatively affect the brain development of the offspring to reduce the learning and memory ability, while DHA can reverse it.

[Effect of propofol on myelin basic protein expression and myelination of oligodendrocytes in neonatal SD rats]

OBJECTIVE

To investigate the effects of different doses of propofol on myelin basic protein (MBP) synthesis and myelination of oligodendrocytes in neonatal SD rats.

METHODS

A total of 57 neonatal SD rats (7 days old) were randomly divided into control group (n=13), vehicle (fat emulsion) group (n=5), and 25, 50 and 100 mg/kg propofol groups (n=13 in each group). Eight hours after a single intraperitoneal injection of propofol or the vehicle, the rats were examined for expressions of mbp mRNA, caspase-3 mRNA, cleaved caspase-3 and MBP in the brain tissues using qPCR and Western blotting. Immunofluorescence assay was used to detect the apoptosis of the oligodendrocytes at 8 h after the injection and the myelination of the corpus callosum and internal capsule at 24 h.

RESULTS

Compared with the control group, the neonatal rats with propofol injections showed significantly down-regulated expressions of mbp mRNA and MBP protein in the brain tissue (P < 0.05). Propofol dose-dependently increased the transcription level of caspase-3 and the protein levels of cleaved caspase-3 at 8 h after the injection (P < 0.05). Propofol injection significantly increased the apoptosis of the oligodendrocytes, and the effect was significantly stronger in 50 and 100 mg/kg groups than in 25 mg/kg group (P < 0.05). At 24 h after propofol injection, myelin formation was significantly decreased in the corpus callosum of the neonatal rats in 100 mg/kg propofol group and in the internal capsule in 50 and 100 mg/kg groups (P < 0.05).

CONCLUSIONS

In neonatal SD rats, propofol can dose-dependently promote oligodendrocyte apoptosis, decrease MBP expressions in the brain, and suppress myelin formation in the corpus callosum and the internal capsule.

Both GSK-3β/CRMP2 and CDK5/CRMP2 pathways participate in the protection of dexmedetomidine against propofol-induced learning and memory impairment in neonatal rats

Dexmedetomidine has been reported to ameliorate propofol-induced neurotoxicity in neonatal animals. However, the underlying mechanism is still undetermined. Glycogen synthase kinase-3β (GSK-3β), cycline dependent kinase-5 (CDK5) and Rho-kinase (RhoA) pathways play critical roles in neuronal development. The present study is to investigate whether GSK-3β, CDK5 and RhoA pathways are involved in the neuroprotection of dexmedetomidine. Seven-day-old (P7) Sprague-Dawley rats were anesthetized with propofol for 6 h. Dexmedetomidine at various concentrations were administered before propofol exposure. Neuroapoptosis, the neuronal proliferation and the level of neurotransmitter in the hippocampus were evaluated. The effects of GSK-3β inhibitor SB415286, CDK5 inhibitor roscovitine or RhoA inhibitor Y276321 on propofol-induced neurotoxicity were assessed. Propofol induced apoptosis in the hippocampal neurons and astrocytes, inhibited neuronal proliferation in the DG region, down-regulated the level of γ-aminobutyric acid (GABA) and glutamate in the hippocampus, and impaired long-term cognitive function. These harmful effects were reduced by pretreatment with 50 μg·kg-1 dexmedetomidine. Moreover, propofol activated GSK-3β and CDK5 pathways, but not RhoA pathway, by reducing the phosphorylation of GSK-3β (ser 9), increasing the expression of CDK5 activator P25 and increasing the phosphorylation of their target sites on CRMP2 shortly after exposure. These effects were reversed by pretreatment with 50 μg·kg-1 dexmedetomidine. Furthermore, SB415286 and roscovitine, not Y276321, attenuated the propofol-induced neuroapoptosis, brain cell proliferation inhibition, GABA and glutamate downregulation, and learning and memory dysfunction. Our results indicate that dexmedetomidine reduces propofol-induced neurotoxicity and neurocognitive impairment via inhibiting activation of GSK-3β/CRMP2 and CDK5/CRMP2 pathways in the hippocampus of neonatal rats.

In utero Exposure to Anesthetics Alters Neuronal Migration Pattern in Developing Cerebral Cortex and Causes Postnatal Behavioral Deficits in Rats

During fetal development, cerebral cortical neurons are generated in the proliferative zone along the ventricles and then migrate to their final positions. To examine the impact of in utero exposure to anesthetics on neuronal migration, we injected pregnant rats with bromodeoxyuridine to label fetal neurons generated at embryonic Day (E) 17 and then randomized these rats to 9 different groups receiving 3 different means of anesthesia (oxygen/control, propofol, isoflurane) for 3 exposure durations (20, 50, 120 min). Histological analysis of brains from 54 pups revealed that significant number of neurons in anesthetized animals failed to acquire their correct cortical position and remained dispersed within inappropriate cortical layers and/or adjacent white matter. Behavioral testing of 86 littermates pointed to abnormalities that correspond to the aberrations in the brain areas that are specifically developing during the E17. In the second set of experiments, fetal brains exposed to isoflurane at E16 had diminished expression of the reelin and glutamic acid decarboxylase 67, proteins critical for neuronal migration. Together, these results call for cautious use of anesthetics during the neuronal migration period in pregnancy and more comprehensive investigation of neurodevelopmental consequences for the fetus and possible consequences later in life.

Validation and bioinformatic analysis of propofol-induced differentially expressed microRNAs in primary cultured neural stem cells

Propofol, a widely used intravenous anesthetic, was previously considered as a neuroprotective agent. Recently, however, accumulating evidence suggests that it may cause neurotoxicity, especially in the development of neural stem cells (NSCs). The potential mechanisms contributing to propofol-induced neurotoxicity during neurogenesis, such as those involving microRNAs (miRNAs), are still unknown. In this study, a total of 27 differentially expressed miRNAs were identified in our initial screen and 6 miRNAs were validated by qRT-PCR. Three miRNAs were up-regulated (miR-377-5p, miR-194-3p and miR-143-5p), and three were down-regulated (miR-3583-3p, miR-466b-5p and miR-410-5p). Following gene ontology and KEGG pathway enrichment analysis, Gabbr1, Canca1b and Gabbr2, which are enriched in the GABAergic synapse pathway, were selected as genes potentially playing a role in propofol-induced neurotoxicity. Gabbr1 and Cacna1b, which are targeted by miRNAs that are up-regulated following propofol exposure, showed decreased expression at the mRNA and protein levels. Gabbr2, targeted by miRNAs that were down-regulated following treatment with propofol, was up-regulated at both the levels of mRNA and protein expression. The two clusters of miRNAs that show differential expression following propofol exposure may act in a synergistic manner to regulate several genes simultaneously during the development of NSCs. Our results may contribute to clarify the molecular mechanism and provide potential therapeutic targets for propofol induced neurotoxicity.

Propofol exposure during early gestation impairs learning and memory in rat offspring by inhibiting the acetylation of histone

Propofol is widely used in clinical practice, including non-obstetric surgery in pregnant women. Previously, we found that propofol anaesthesia in maternal rats during the third trimester (E18) caused learning and memory impairment to the offspring rats, but how about the exposure during early pregnancy and the underlying mechanisms? Histone acetylation plays an important role in synaptic plasticity. In this study, propofol was administered to the pregnant rats in the early pregnancy (E7). The learning and memory function of the offspring were tested by Morris water maze (MWM) test on post-natal day 30. Two hours before each MWM trial, histone deacetylase 2 (HDAC2) inhibitor, suberoylanilide hydroxamic acid (SAHA), Senegenin (SEN, traditional Chinese medicine), hippyragranin (HGN) antisense oligonucleotide (HGNA) or vehicle were given to the offspring. The protein levels of HDAC2, acetylated histone 3 (H3) and 4 (H4), cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), N-methyl-D-aspartate receptor (NMDAR) 2 subunit B (NR2B), HGN and synaptophysin in offspring's hippocampus were determined by Western blot or immunofluorescence test. It was discovered that infusion with propofol in maternal rats on E7 leads to impairment of learning and memory in offspring, increased the protein levels of HDAC2 and HGN, decreased the levels of acetylated H3 and H4 and phosphorylated CREB, NR2B and synaptophysin. HDAC2 inhibitor SAHA, Senegenin or HGN antisense oligonucleotide reversed all the changes. Thus, present results indicate exposure to propofol during the early gestation impairs offspring's learning and memory via inhibiting histone acetylation. SAHA, Senegenin and HGN antisense oligonucleotide might have therapeutic value for the adverse effect of propofol.

KIF17 mediates the learning and memory impairment in offspring induced by maternal exposure to propofol during middle pregnancy

Preclinical studies suggest that propofol may cause neuronal injury to the developing brain. A previous study demonstrated that, in a rat model, maternal exposure to propofol during early or late pregnancy caused learning and memory impairment in the offspring. However, whether propofol exposure during middle pregnancy can cause long‑term behavioral deficits in the offspring remains to be elucidated. N‑methyl‑D‑aspartate receptor 2B subunit (NR2B) serves a critical role in memory modulation. To exert its function, NR2B must be transported to the neuronal membrane by kinesin family member 17 (KIF17). The aim of the present study was to investigate the role of KIF17 in learning and memory impairment in rat offspring caused by propofol exposure during middle pregnancy. Pregnant rats were exposed to propofol on gestational day 14 (G14) for 4 and 8 h, with control pregnant rats receiving an equal volume of normal saline. The learning and memory of the offspring was assessed using Morris water maze tests from postnatal day 30 (P30) to P36. The levels of KIF17 protein, total NR2B (T‑NR2B) and membrane NR2B (M‑NR2B) in the hippocampus were detected using western blotting. The results demonstrated that propofol exposure caused learning and memory deficits and decreased KIF17 and M‑NR2B protein levels in the hippocampus; however, no but changes in the expression of T‑NR2B were observed. These results indicate that maternal propofol exposure during middle pregnancy impairs learning and memory in offspring rats by suppressing the expression of KIF17 and inhibiting the translocation of NR2B to the neuronal membrane.

[Effects of propofol on myelin basic protein expression in oligodendrocytes of SD rats at different developmental stages]

OBJECTIVE

To investigate the effect of propofol on myelin basic protein (MBP) expression in oligodendrocytes of SD rats at different developmental stages.

METHODS

This study was conducted in 3?, 7?, 14? and 21?day?old SD rats (40 in each age group). In each group, the rats were randomized equally into control group and experimental group, and in the control group, the rats received an intraperitoneal injection of 25 mg/kg medium?long?chain fat emulsion followed by injections at a half dose every 20 min for 8 h; the rats in the experimental group were given injections of propofolmedium (at the initial dose of 25 mg/kg) in the same manner. The transcriptional levels of MBP and caspase?3 in the brain tissues were detected by qRT?PCR, and the protein expression of MBP was with Western blotting and immunehistochemistry.

RESULTS

Compared with those in the control groups, the expression of MBP mRNA was significantly down?regulated while caspase?3 mRNA was up?regulated in 3?, 7? and 14?day?old rats in the experimental groups (P<0.05). The protein expression of MBP in 7? and 14?day?old rats was significantly decreased in the experimental groups compared with the control groups (P<0.05). The expression of caspase?3 mRNA or MBP protein in 21?day?old rats showed no significant difference between the two groups (P>0.05).

CONCLUSION

Propofol can down?regulate the expression of MBP at both the mRNA and protein levels in SD rats, especially in those at 7 and 14 days of age.

Pink1 attenuates propofol-induced apoptosis and oxidative stress in developing neurons

BACKGROUND

The underlying mechanisms of propofol-induced neurotoxicity in developing neurons are still not completely understood. We examined the role of PTEN-induced kinase 1 (Pink1), an antioxidant protein, in propofol-induced apoptosis in developing neurons.

MATERIALS AND METHODS

Primary hippocampal neurons isolated from neonatal Sprague-Dawley rats were exposed to propofol 20 μM for 2, 4, 6 and 12 h. Subsequently, neurons underwent overexpression and knockdown of Pink1, followed by propofol exposure (20 μM, 6 h). Neuron apoptosis was detected by terminal transferase deoxyuridine triphosphate-biotin nick-end labeling (TUNEL). Reactive oxygen species (ROS) production in neurons was detected by using a 2,7-dichlorodihydro-fluorescein diacetate probe and target protein or mRNA levels were analyzed by Western blotting or real-time polymerase chain reaction.

RESULTS

Propofol treatment time-dependently increased the number of TUNEL-positive neurons and the expression levels of cleaved caspase-3 and B-cell lymphoma 2 (BcL-2) associated X protein, but decreased expression levels of BcL-2. Furthermore, propofol treatment time-dependently reduced the expression levels of Pink1 mRNA and protein. ROS production and the markers of oxidative stress, 2,4-dinitrophenol and 4-hydroxynonenal, were increased by propofol treatment. However, these propofol-induced changes were significantly restored by Pink1 overexpression.

CONCLUSIONS

Pink1 plays an important role in neuronal apoptosis induced by propofol. Our results may provide some new insights in propofol-induced neurotoxicity in developing neurons.

Sevoflurane Affects Oxidative Stress and Alters Apoptosis Status in Children and Cultured Neural Stem Cells

Anesthesia-induced neurotoxicity in immature animals has raised concerns about similar effects occurring in young children. Our study investigated two commonly used anesthetics-sevoflurane and propofol-for neurotoxicity in young children. Forty-seven children (aged 12-36 months) undergoing hypospadias repair surgery were randomized to receive sevoflurane (SG, n = 24) or propofol (PG, n = 23) general anesthesia. Venous blood was collected at three different times-immediately after induction, 2 h, and 3 days after surgery. The cellular portion was assessed for antioxidant defense and DNA damage, using enzyme assay kits and qRT-PCR, respectively, while serum was used to treat cultured neural stem cells (NSCs). MTT assay and TUNEL staining were performed, and the mRNA levels of antioxidant enzymes and apoptosis indicators were evaluated by qRT-PCR. Antioxidant defense and apoptosis status in the SG group were significantly higher than in the PG group at 2 h after surgery. Additionally, exposure of NSCs to postoperative serum of the SG group resulted in decreased cell density and viability, increased TUNEL-positive cells, elevated mRNA levels of antioxidant enzymes, and cleaved caspase-3 expression. Our data shows for the first time that in young children, administration of sevoflurane, but not propofol, leads to temporally increased antioxidant defense and apoptosis status as well as damage of NSCs.

Effects of Propofol Treatment in Neural Progenitors Derived from Human-Induced Pluripotent Stem Cells

Propofol is an intravenous anesthetic that has been widely used in clinics. Besides its anesthetic effects, propofol has also been reported to influence the regulation of the autonomic system. Controversies exist with regard to whether propofol exposure is safe for pregnant women and young children. In this work, human-induced pluripotent stem cell- (hiPSC-) derived neural progenitor cells (NPCs) were treated with propofol at 20, 50, 100, or 300 μM for 6 h or 24 h, and acute and subacute cell injury, cell proliferation, and apoptosis were evaluated. Comparison of genome-wide gene expression profiles was performed for treated and control iPSC-NPCs. Propofol treatment for 6 h at the clinically relevant concentration (20 or 50 μM) did not affect cell viability, apoptosis, or proliferation, while propofol at higher concentration (100 or 300 μM) decreased NPC viability and induced apoptosis. In addition, 20 μM propofol treatment for 6 h did not alter global gene expression. In summary, propofol treatment at commonly practiced clinical doses for 6 h did not have adverse effects on hiPSC-derived NPCs. In contrast, longer exposure and/or higher concentration could decrease NPC viability and induce apoptosis.

Propofol's Effects on the Fetal Brain for Non-Obstetric Surgery

While the use of Propofol has been increasing in usage for general surgical procedures since its release to market, there has been little work done on its potential link to neurotoxicity in humans. Only recently, following the release of a warning label from the United States Food and Drug Administration (USFDA) regarding a potential link to "neurotoxicity" in the neonate, did the surgical and anesthesiology communities become more aware of its potential for harm. Given the widespread use of this drug in clinical practice, the warning label naturally raised controversy regarding intrapartum Propofol usage. While intended to generate further studies, the lack of a viable anesthetic alternative raises issues regarding its current usage for surgical procedures in pregnant women. To answer the question whether current evidence is supportive of Propofol usage at its current levels in pregnant women, this review summarizes available evidence of fetal Propofol exposure in animal studies.

Recent Insights Into Molecular Mechanisms of Propofol-Induced Developmental Neurotoxicity: Implications for the Protective Strategies

Mounting evidence has demonstrated that general anesthetics could induce developmental neurotoxicity, including acute widespread neuronal cell death, followed by long-term memory and learning abnormalities. Propofol is a commonly used intravenous anesthetic agent for the induction and maintenance of anesthesia and procedural and critical care sedation in children. Compared with other anesthetic drugs, little information is available on its potential contributions to neurotoxicity. Growing evidence from multiple experimental models showed a similar neurotoxic effect of propofol as observed in other anesthetic drugs, raising serious concerns regarding pediatric propofol anesthesia. The aim of this review is to summarize the current findings of propofol-induced developmental neurotoxicity. We first present the evidence of neurotoxicity from animal models, animal cell culture, and human stem cell-derived neuron culture studies. We then discuss the mechanism of propofol-induced developmental neurotoxicity, such as increased cell death in neurons and oligodendrocytes, dysregulation of neurogenesis, abnormal dendritic development, and decreases in neurotrophic factor expression. Recent findings of complex mechanisms of propofol action, including alterations in microRNAs and mitochondrial fission, are discussed as well. An understanding of the toxic effect of propofol and the underlying mechanisms may help to develop effective novel protective or therapeutic strategies for avoiding the neurotoxicity in the developing human brain.

General Anesthesia During the Third Trimester: Any Link to Neurocognitive Outcomes?

Rodent studies on the effect of general anesthesia during the third trimester on neurocognitive outcomes are mixed, but primate studies suggest that a clinically relevant exposure to anesthetic agents during the third trimester can trigger neuronal and glial cell death. Human studies are conflicting and the evidence is weak. This is an up-to-date review of the literature on the neurodevelopmental effects of anesthetic agents administered during the third trimester. Early brain development and critical periods of neurodevelopment as it relates to neurotoxicity are highlighted. Rodent, nonhuman primate, and population studies are discussed and placed in the context of clinical practice.

Propofol exposure during late stages of pregnancy impairs learning and memory in rat offspring via the BDNF-TrkB signalling pathway

The brain‐derived neurotrophic factor (BDNF)‐tyrosine kinase B (TrkB) (BDNF‐TrkB) signalling pathway plays a crucial role in regulating learning and memory. Synaptophysin provides the structural basis for synaptic plasticity and depends on BDNF processing and subsequent TrkB signalling. Our previous studies demonstrated that maternal exposure to propofol during late stages of pregnancy impaired learning and memory in rat offspring. The purpose of this study is to investigate whether the BDNF‐TrkB signalling pathway is involved in propofol‐induced learning and memory impairments. Propofol was intravenously infused into pregnant rats for 4 hrs on gestational day 18 (E18). Thirty days after birth, learning and memory of offspring was assessed by the Morris water maze (MWM) test. After the MWM test, BDNF and TrkB transcript and protein levels were measured in rat offspring hippocampus tissues using real‐time PCR (RT‐PCR) and immunohistochemistry (IHC), respectively. The levels of phosphorylated‐TrkB (phospho‐TrkB) and synaptophysin were measured by western blot. It was discovered that maternal exposure to propofol on day E18 impaired spatial learning and memory of rat offspring, decreased mRNA and protein levels of BDNF and TrkB, and decreased the levels of both phospho‐TrkB and synaptophysin in the hippocampus. Furthermore, the TrkB agonist 7,8‐dihydroxyflavone (7,8‐DHF) reversed all of the observed changes. Treatment with 7,8‐DHF had no significant effects on the offspring that were not exposed to propofol. The results herein indicate that maternal exposure to propofol during the late stages of pregnancy impairs spatial learning and memory of offspring by disturbing the BDNF‐TrkB signalling pathway. The TrkB agonist 7,8‐DHF might be a potential therapy for learning and memory impairments induced by maternal propofol exposure.

Tissue plasminogen activator (tPA) attenuates propofol-induced apoptosis in developing hippocampal neurons

Background

We investigated the effect of propofol on the tissue plasminogen activator (tPA) release in developing hippocampal neurons, and explored the effects of exogenous tPA on the propofol-induced neuron apoptosis.

Methods

Primary hippocampal neurons isolated from neonatal Sprague-Dawley rats were exposed to propofol (20, 50, and 100 μM) for 6 h either one time or three times. Finally, neurons were pretreated with exogenous tPA (5 µg/ml), followed by propofol exposure (100 μM, 6 h). The neuron apoptosis was detected by terminal transferase deoxyuridine triphosphate-biotin nick-end labeling (TUNEL) and the protein expression of cleaved caspase-3 (Cl-Csp3) was analyzed by western blot, the tPA in media was tested by enzyme-linked immunosorbent assay.

Results

Propofol exposure significantly increased the number of TUNEL-positive neurons and Cl-Csp3 expression in developing hippocampal neurons. Propofol decreased tPA level in the media of developing hippocampal neurons. The neuron appotosis induced by propofol was attenuated by pretreatment of tPA.

Conclusion

Propofol exposure decreased tPA release in developing hippocampal neurons. The addition of tPA could partially reverse the apoptotic effect of propofol.

Propofol-Induced Neurotoxicity in the Fetal Animal Brain and Developments in Modifying These Effects-An Updated Review of Propofol Fetal Exposure in Laboratory Animal Studies

In the past twenty years, evidence of neurotoxicity in the developing brain in animal studies from exposure to several general anesthetics has been accumulating. Propofol, a commonly used general anesthetic medication, administered during synaptogenesis, may trigger widespread apoptotic neurodegeneration in the developing brain and long-term neurobehavioral disturbances in both rodents and non-human primates. Despite the growing evidence of the potential neurotoxicity of different anesthetic agents in animal studies, there is no concrete evidence that humans may be similarly affected. However, given the growing evidence of the neurotoxic effects of anesthetics in laboratory studies, it is prudent to further investigate the mechanisms causing these effects and potential ways to mitigate them. Here, we review multiple studies that investigate the effects of in utero propofol exposure and the developmental agents that may modify these deleterious effects.

Effect of Continuous Propofol Infusion in Rat on Tau Phosphorylation with or without Temperature Control

Several studies suggest a relationship between anesthesia-induced tau hyperphosphorylation and the development of postoperative cognitive dysfunction. This study further characterized the effects of continuous propofol infusion on tau protein phosphorylation in rats, with or without temperature control. Propofol was administered intravenously to 8-10-week-old male Sprague-Dawley rats and infused to the loss of the righting reflex for 2 h continuously. Proteins from cortex and hippocampus were examined by western blot and immunohistochemistry. Rectal temperature was significantly decreased during propofol infusion. Propofol with hypothermia significantly increased phosphorylation of tau at AT8, AT180, Thr205, and Ser199 in cortex and hippocampus except Ser396. With temperature maintenance, propofol still induced significant elevation of AT8, Thr205, and Ser199 in cortex and hippocampus; however, increase of AT180 and Ser396 was only found in hippocampus and cortex, respectively. Differential effects of propofol with or without hypothermia on multiple tau related kinases, such as Akt/GSK3β, MAPK pathways, or phosphatase (PP2A), were demonstrated in region-specific manner. These findings indicated that propofol increased tau phosphorylation under both normothermic and hypothermic conditions, and temperature control could partially attenuate the hyperphosphorylation of tau. Further studies are warranted to determine the long-term impact of propofol on the tau pathology and cognitive functions.

Repeated neonatal propofol administration induces sex-dependent long-term impairments on spatial and recognition memory in rats

Propofol is an anesthetic agent that gained wide use because of its fast induction of anesthesia and rapid recovery post-anesthesia. However, previous studies have reported immediate neurodegeneration and long-term impairment in spatial learning and memory from repeated neonatal propofol administration in animals. Yet, none of those studies has explored the sex-specific long-term physical changes and behavioral alterations such as social (sociability and social preference), emotional (anxiety), and other cognitive functions (spatial working, recognition, and avoidance memory) after neonatal propofol treatment. Seven-day-old Wistar-Kyoto (WKY) rats underwent repeated daily intraperitoneal injections of propofol or normal saline for 7 days. Starting fourth week of age and onwards, rats were subjected to behavior tests including open-field, elevated-plus-maze, Y-maze, 3-chamber social interaction, novel-object-recognition, passive-avoidance, and rotarod. Rats were sacrificed at 9 weeks and hippocampal protein expressions were analyzed by Western blot. Results revealed long-term body weight gain alterations in the growing rats and sex-specific impairments in spatial (female) and recognition (male) learning and memory paradigms. A markedly decreased expression of hippocampal NMDA receptor GluN1 subunit in female- and increased expression of AMPA GluR1 subunit protein expression in male rats were also found. Other aspects of behaviors such as locomotor activity and coordination, anxiety, sociability, social preference and avoidance learning and memory were not generally affected. These results suggest that neonatal repeated propofol administration disrupts normal growth and some aspects of neurodevelopment in rats in a sex-specific manner.

Propofol inhibits proliferation and induces neuroapoptosis of hippocampal neurons in vitro via downregulation of NF-κB p65 and Bcl-2 and upregulation of caspase-3

Propofol is widely used in paediatric anaesthesia and intensive care unit because of its essentially short-acting anaesthetic effect. Recent data have shown that propofol induced neurotoxicity in developing brain. However, the mechanisms are not extremely clear. To gain a better insight into the toxic effects of propofol on hippocampal neurons, we treated cells at the days in vitro 7 (DIV 7), which were prepared from Sprague-Dawley embryos at the 18th day of gestation, with propofol (0.1-1000 μM) for 3 h. A significant decrease in neuronal proliferation and a remarkable increase in neuroapoptosis were observed in DIV 7 hippocampal neurons as measured by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay and apoptosis assay respectively. Moreover, propofol treatment decreased the nuclear factor kappaB (NF-κB) p65 expression, which was accompanied by a reduction in B-cell lymphoma 2 (Bcl-2) mRNA and protein levels, increased caspase-3 mRNA and activation of caspase-3 protein. These results indicated that downregulation of NF-κB p65 and Bcl-2 were involved in the potential mechanisms of propofol-induced neurotoxicity. This likely led to the caspase-3 activation, triggered apoptosis and inhibited the neuronal growth and proliferation that we have observed in our in vitro systems.