Dexmedetomidine reduced sevoflurane-induced neurodegeneration and long-term memory deficits in neonatal rats

Research status and advances in dexmedetomidine for sepsis‑induced multiple organ dysfunction syndrome (Review)

Sepsis‑induced organ dysfunction syndrome (ODS) arises from a dysregulated response to infection, leading to multiple life‑threatening organ dysfunctions, and is a common complication in critically ill patients. Sepsis results in varying degrees of injury to the brain, lungs, kidneys and liver, culminating in immune dysfunction and multiple ODS (MODS). Current evidence indicates a direct correlation between the severity of organ injury and the prognosis of septic patients. Understanding the mechanisms of MODS in sepsis and developing effective management strategies are vital research areas. The protective effects of dexmedetomidine (DEX) on sepsis are well established, demonstrating its capacity to mitigate injuries to the brain, lungs, kidneys, liver and immune system. The present study reviews recent research progress on the role and mechanisms of action of DEX in the treatment of sepsis.

A Scoping Review of the Mechanisms Underlying Developmental Anesthetic Neurotoxicity

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

The Role of Intravenous Anesthetics for Neuro: Protection or Toxicity?

The primary intravenous anesthetics employed in clinical practice encompass dexmedetomidine (Dex), propofol, ketamine, etomidate, midazolam, and remimazolam. Apart from their established sedative, analgesic, and anxiolytic properties, an increasing body of research has uncovered neuroprotective effects of intravenous anesthetics in various animal and cellular models, as well as in clinical studies. However, there also exists conflicting evidence pointing to the potential neurotoxic effects of these intravenous anesthetics. The role of intravenous anesthetics for neuro on both sides of protection or toxicity has been rarely summarized. Considering the mentioned above, this work aims to offer a comprehensive understanding of the underlying mechanisms involved both in the central nerve system (CNS) and the peripheral nerve system (PNS) and provide valuable insights into the potential safety and risk associated with the clinical use of intravenous anesthetics.

Subunit-specific mechanisms of isoflurane-induced acute tonic inhibition in dentate gyrus granule neuron

Prolonged exposure to volatile anesthetics may raise the risk of developing cognitive impairment by acting on gamma-a Aminobutyric acid A receptors (GABAAR). The dentate gyrus plays an important role in the hippocampus and has a high potential for neural plasticity. However, it is unknown whether prolonged anesthesia induces a change in acute phasic or tonic inhibition in dentate gyrus granule cells (DGGCs) by acting on GABAAR. In order to verify the effects of volatile anesthetics on the current in DGGCs, a whole-cell patch was applied to record acute brain slices, and this study indicated that 4 h but not 2 h of isoflurane (ISO) exposure induced significantly larger tonic currents in DGGCs other than hippocampal CA1 pyramidal and thalamic relay neurons. Furthermore, this study demonstrated that the increased tonic current in DGGCs was dependent on the δ subunit-containing GABAARs by using transgenic δ subunit knockout mice. In conclusion, the δ subunit specific GABAAR is the key element that increased acute tonic inhibition in DGGCs of mice after prolonged ISO exposure, which may be one of the mechanisms of ISO neurotoxicity to the developing brain.

Dexmedetomidine suppresses hippocampal astrocyte pyroptosis in cerebral hypoxic-ischemic neonatal rats by upregulating microRNA-148a-3p to inactivate the STAT/JMJD3 axis

OBJECTIVE

Dexmedetomidine (DEX), a selective α2-adrenoceptor agonist, is an anesthetic and sedative agent and has been reported to confer neuroprotective effects after cerebral hypoxic ischemia (CHI). This study was undertaken to elucidate the mechanisms by which microRNA (miR)-148a-3p is involved in the neuroprotective effect of DEX on hypoxic-ischemic brain damage in neonatal rats.

METHODS

Neonatal rats were exposed to CHI conditions, a miR-148a-3p inhibitor, and DEX. Hippocampal astrocytes were isolated to construct an oxygen-glucose deprivation (OGD) model. qRT-PCR and western blot were utilized to inspect miR-148a-3p, STAT1, STAT3, JMJD3, cleaved-Caspase-1, ASC, NLRP3, GSDMD, and GSDMD-N expression in rats and astrocytes. TUNEL staining was employed to measure astrocyte apoptosis rate, immunofluorescence to inspect cleaved-Caspase-1 and ASC levels, and ELISA to determine IL-1β and IL-18 expression. The target genes of miR-148a-3p were predicted using online software and verified by a dual-luciferase reporter gene assay.

RESULTS

A prominent increase in astrocyte apoptosis rate and the expression of pyroptosis- and inflammation-related factors were found in rats with CHI and OGD-treated astrocytes. DEX suppressed astrocyte apoptosis rate and decreased expression of pyroptosis- and inflammation-related factors. Knockdown of miR-148a-3p facilitated astrocyte pyroptosis, indicating that DEX exerted its protective effect by upregulating miR-148a-3p. miR-148a-3p negatively mediated STAT to inactivate JMJD3. Overexpression of STAT1 and STAT3 facilitated pyroptosis in astrocytes, which was negated by the overexpression of miR-148a-3p.

CONCLUSION

DEX inhibited hippocampal astrocyte pyroptosis by upregulating miR-148a-3p to inactivate the STAT/JMJD3 axis, thereby alleviating cerebral damage in neonatal rats with CHI.

Dexmedetomidine: An Alternative to Pain Treatment in Neonatology

Infants might be exposed to pain during their admissions in the neonatal intensive care unit [NICU], both from their underlying conditions and several invasive procedures required during their stay. Considering the particularities of this population, recognition and adequate management of pain continues to be a challenge for neonatologists and investigators. Diverse therapies are available for treatment, including non-pharmacological pain management measures and pharmacological agents (sucrose, opioids, midazolam, acetaminophen, topical agents…) and research continues. In recent years one of the most promising drugs for analgesia has been dexmedetomidine, an alpha-2 adrenergic receptor agonist. It has shown a promising efficacy and safety profile as it produces anxiolysis, sedation and analgesia without respiratory depression. Moreover, studies have shown a neuroprotective role in animal models which could be beneficial to neonatal population, especially in preterm newborns. Side effects of this therapy are mainly cardiovascular, but in most studies published, those were not severe and did not require specific therapeutic measures for their resolution. The main objective of this article is to summarize the existing literature on neonatal pain management strategies available and review the efficacy of dexmedetomidine as a new therapy with increasing use in the NICU.

Prevention of Dexmedetomidine on Postoperative Delirium and Early Postoperative Cognitive Dysfunction in Elderly Patients Undergoing Thoracoscopic Lobectomy

Objective

To investigate the effect of dexmedetomidine on postoperative cognitive function and delirium in elderly patients undergoing thoracoscopic lobectomy.

Methods

109 elderly patients (age is more than 65 years) who underwent thoracoscopic lobectomy in our hospital from June 2020 to Feb 2022 were randomly divided into the dexmedetomidine (DEX) group (n = 54) and the control group (n = 55). The patients in the experimental group were given dexmedetomidine by intravenous pump, intravenous pump 0.5 μg/kg within 10 minutes, and maintained the speed of 0.5 μg/(kg. h) to 30 min before the operation was ended. The control group was given the same amount of normal saline. Delirium assessment-severity (CAM-S) assessment and Mini-Cog were used to assess the severity levels of POD and POCD 24 h before, 6 hours after, one day after the operation, three days after the operation, and 1 week after the operation. Serum TNF-αα and NSE levels were assessed by using enzyme-linked immunosorbent assay. NRS pain marks were assessed in the DEX group at postanesthesia care unit (PACU) and 24 postoperation. Surgical pierhysmographic index (SPI) evaluation was performed at five time points.

Results

The Mini-Cog scores in the DEX group were markedly enhanced compared with those in the saline group 6 and 24 hours after the operation. The SPI values in the DEX group were markedly reduced within 2 min after intubation and at surgical sutures. Moreover, the CAM scores in the DEX group were markedly reduced 24 hours after the operation. Tumor necrosis factor-α (TNF-α) and neuron-specific enolase (NSE) levels were significantly decreased in the DEX group at T1∼T3.

Conclusion

The use of dexmedetomidine in the thoracoscopic lobectomy in elderly patients could reduce the occurrence and severity of postoperative cognitive dysfunction and delirium.

Dexmedetomidine Diminishes, but Does Not Prevent, Developmental Effects of Sevoflurane in Neonatal Rats

BACKGROUND

Sevoflurane (SEVO) increases neuronal excitation in neonatal rodent brains through alteration of gamma aminobutyric acid (GABA)(A) receptor signaling and increases corticosterone release. These actions may contribute to mechanisms that initiate the anesthetic's long-term neuroendocrine and neurobehavioral effects. Dexmedetomidine (DEX), a non-GABAergic α2-adrenergic receptor agonist, is likely to counteract SEVO-induced neuronal excitation. We investigated how DEX pretreatment may alter the neurodevelopmental effects induced by SEVO in neonatal rats.

METHODS

Postnatal day (P) 5 Sprague-Dawley male rats received DEX (25 µg/kg, intraperitoneal) or vehicle before exposure to 2.1% SEVO for 6 hours (the DEX + SEVO and SEVO groups, respectively). Rats in the DEX-only group received DEX without exposure to SEVO. A subcohort of P5 rats was used for electroencephalographic and serum corticosterone measurements. The remaining rats were sequentially evaluated in the elevated plus maze on P80, prepulse inhibition of the acoustic startle response on P90, Morris water maze (MWM) starting on P100, and for corticosterone responses to physical restraint for 30 minutes on P120, followed by assessment of epigenomic DNA methylation patterns in the hippocampus.

RESULTS

Acutely, DEX depressed SEVO-induced electroencephalogram-detectable seizure-like activity (mean ± SEM, SEVO versus DEX + SEVO, 33.1 ± 5.3 vs 3.9 ± 5.3 seconds, P < .001), but it exacerbated corticosterone release (SEVO versus DEX + SEVO, 169.935 ± 20.995 versus 280.853 ± 40.963 ng/mL, P = .043). DEX diminished, but did not fully abolish, SEVO-induced corticosterone responses to restraint (control: 11625.230 ± 877.513, SEVO: 19363.555 ± 751.325, DEX + SEVO: 15012.216 ± 901.706, DEX-only: 12497.051 ± 999.816; F[3,31] = 16.878, P < .001) and behavioral deficiencies (time spent in the target quadrant of the MWM: control: 31.283% ± 1.722%, SEVO: 21.888% ± 2.187%, DEX + SEVO: 28.617% ± 1.501%, DEX-only: 31.339% ± 3.087%; F[3,67] = 3.944, P = .012) in adulthood. Of the 391 differentially methylated genes in the SEVO group, 303 genes in the DEX + SEVO group had DNA methylation patterns that were not different from those in the control group (ie, they were normal). DEX alone did not cause acute or long-term functional abnormalities.

CONCLUSIONS

This study suggests that the ability of DEX to depress SEVO-induced neuronal excitation, despite increasing corticosterone release, is sufficient to weaken mechanisms leading to long-term neuroendocrine/neurobehavioral abnormalities. DEX may prevent changes in DNA methylation in the majority of genes affected by SEVO, epigenetic modifications that could predict abnormalities in a wide range of functions.

Remimazolam induced cognitive dysfunction in mice via glutamate excitotoxicity

Objective

Several lines of evidence demonstrated the role of anesthetic drugs in cognitive functions. Some anesthetic agents have been confirmed to be associated with long-term spatial memory and learning in aged animal models.

Methods

C57BL/6 mice were divided into four different groups based on different concentrations of remimazolam treatments. Behavioral phenotype was observed by open field, rota rod, Morris water maze, and elevated plus maze test. Western blot was performed to see the expression pattern of different proteins. Confocal microscopy images were taken for neuronal and glial cells to see the effect of remimazolam on CNS cells.

Results

We showed that remimazolam, a new anesthetic drug, impaired cognitive behavior. Repetitive doses of remimazolam have been found to induce neuronal loss with a significant change in morphology. Here, we showed that a higher concentration of remimazolam had a significant effect on CNS cell activation. We showed that remimazolam caused memory dysfunction by inducing neuronal apoptosis via glutamate excitotoxicity. It also exhibited amyloid β plaque in the brain via abnormal phosphorylation of tau protein. Remimazolam-mediated regulation of glial cells in mouse cortex was observed and robust activation of astrocytes and microglial cells was found. Finally, we assessed the behavioral phenotype of mice and found that treatment with remimazolam induced significant behavioral changes and memory dysfunction.

Conclusions

This study provides insight into the mechanism of anesthetic drug-induced memory deficits and may help improve the therapeutic effects of anesthesia agents in clinical applications.

Sevoflurane induced neurotoxicity in neonatal mice links to a GSK3β/Drp1-dependent mitochondrial fission and apoptosis

Mitochondria damage and apoptosis were found associated with sevoflurane induced neurotoxicity in developing brains of rodent and neuro cell lines. The detailed upstream mechanism remains unclear. This study explored whether sevoflurane induces neurotoxicity by activating a GSK3β (glycogen synthase kinase 3β)/Drp1 (dynamin-related protein-1)-dependent mitochondrial fission and apoptosis. Our results showed that sevoflurane exposure promoted mitochondria fission in hippocampus of neonatal mice, resulted in a prolonged escape latency from P32 (32-day-postnatal) to P35, and decreased platform crossing times on P36 as compared to the control treatment. Additionally, sevoflurane upregulated GSK3β stability and activation, promoted phosphorylation of Drp1 at Ser⁶¹⁶ along with its translocation to mitochondria and resulted in increasing cytochrome c and cleaved casepase-3 in hippocampus of neonatal mice and in human SK-N-SH cells. Simultaneously, sevoflurane promoted the interaction between Drp1 and GSK3β. Furthermore, GSK3β activated phosphorylation of Drp1 at Ser⁶¹⁶, induced mitochondrial fission, loss of mitochondrial membrane potential (MMP) and apoptosis in SK-N-SH cells, which was attenuated by TDZD-8, an inhibitor of GSK3β. In conclusion, sevoflurane induced neurotoxicity links to a GSK3β/Drp1 dependent mitochondrial fission and apoptosis.

Protective Effects of Dexmedetomidine on Hippocampal Neurons in Rats Anesthetized with Sevoflurane

To explore effects of dexmedetomidine (Dex) on cognitive function and hippocampal neuronal apoptosis in rats anesthetized with sevoflurane (Sevo), and regulation of brain-derived neurotrophic factor (BDNF) and its downstream signaling. 30 Sprague-Dawley (SD) rats were randomly divided into control group inhaled 29% concentration oxygen), Sevo group (2 L/min oxygen flow +1.5% Sevo), Dex+Sevo group (after injection of 20 μg/kg Dex, treated with 2L/min oxygen flow+1.5% Sevo). Haematoxylin and eosin (HE) staining and Nissl’s staining were adopted to detect morphological and functional changes in hippocampus of rats. Apoptosis was detected by immunofluorescence, BDNF expression was detected by immunohistochemistry. Reverse transcription PCR (RT-PCR) was conducted to detect mRNA expression of key proteins in downstream signaling of BDNF. The results showed that Sevo induced apoptosis of hippocampus neurons, while Dex improved Sevo induced apoptosis. In contrast to the control, the positive expression of BDNF in hippocampus of Sevo group was notably decreased (P < 0.05), and that of Dex+Sevo group was notably higher in contrast to Sevo group (P < 0.05). Signaling pathways of MAPK, PI3K-Akt, and Ras were predicted by String software as the downstream pathways of BDNF. RT-PCR results showed that these 3 signaling pathways were involved in Dex improving Sevo-induced cognitive impairment and hippocampal neuron apoptosis. In conclusion, Dex could improve cognitive dysfunction and hippocampal neuron apoptosis in rats induced by Sevo, and the mechanism was related to upregulation of BDNF expression and activation of pathways of MAPK, PI3K-Akt, and Ras.

Sevoflurane Promotes Neurodegeneration Through Inflammasome Formation in APP/PS1 Mice

Sevoflurane (SEVO) is a highly fluorinated methyl isopropyl ether used as an inhalational anesthetic for general anesthesia. Previous studies have shown that SEVO may induce impaired memory and recognition ability and may be associated with neurodegenerative disease, e.g., Alzheimer’s disease (AD). However, the underlying mechanism remains unknown. Here, we used a mouse AD model, APP/PS1, to study the effects of SEVO on neurodegeneration occurring in AD. We found that SEVO exposure significantly impaired the spatial reference memory, sensorimotor, and cognitive function of the mice. Mechanistically, we found that SEVO induced formation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome and its downstream caspase 1-mediated production of IL-1β and IL-18, which subsequently deactivated brain-derived neurotrophic factor (BDNF) to promote neurodegeneration. Together, these data suggest that NLRP3 inflammasome is essential for SEVO-induced AD.

Ultrasonic Image Restoration Algorithm for Prevention of Nervous Disorders during the Recovery Period of Patients Receiving Sevoflurane Anesthesia

In this article, dexmedetomidine (Dex) was used to prevent neurological disorders in patients anesthetized with sevoflurane and the effect was analyzed using ultrasound images based on the restoration algorithm of the linear system model. Children injected with Dex were in the experimental group, while children injected with normal saline were in the control group. The mean arterial pressure (MAP), arterial oxygen saturation (SpO2), heart rate (HR), Pediatric anesthesia agitation scale (PAED) score, Face, Legs, Activity, Cry, Consolability (FLACC) score, and adverse drug event (ADE) in the two groups were compared before the injection (T1), at 5 min (T2), 10 min (T3), and 20 min (T4) after the injection, and when the patient came to himself (T5). It was found that in contrast with the control group, the MAP in the experimental group at T2, T3, and T4 periods was lower, while it was higher at T5 period and its HR at T2, T3, T4, and T5 periods was higher (P < 0.05); the PAED and FLACC scores were lower (P < 0.05), and the incidence of ADE (10.53%) was lower than that in the control group (31.58%) (P < 0.05). However, SpO2 at different periods showed no obvious differences between the two groups (P > 0.05). In conclusion, the restoration algorithm-based ultrasound images had high quality, and they demonstrated good application value in evaluating the effect of Dex to prevent neurological disorders in patients anesthetized by sevoflurane.

Dexmedetomidine alleviates traumatic spinal cord injury in rats via inhibiting apoptosis induced by endoplasmic reticulum stress

OBJECTIVE

To investigate the protective effect of dexmedetomidine (Dex) on traumatic spinal cord injury (TSCI) and to evaluate the involvement of inhibition of endoplasmic reticulum (ER) stress response in the potential mechanism.

METHOD

Sprague-Dawley rats were randomly divided into five groups. The hind limb locomotor function of rats was evaluated at 1, 3 and 7 days after the operation. At 7 days after the operation, spinal cord specimens were obtained for hematoxylin and eosin (H&E), Nissl and TUNEL staining, as well as immunofluorescence and Western blot analyses to detect the level of apoptosis and the levels of proteins related to ER stress.

RESULTS

7 days after the operation, Dex treatment promoted the recovery and also inhibited apoptosis of neurons in the spinal cord. Additionally, Dexinhibited the expression of proteins related to ER stress response after spinal cord injury.

CONCLUSIONS

Dex improves the neurological function of rats with TSCI and reduces apoptosis of spinal cord neurons. The potential mechanism is related to the inhibition of the ER stress response.

Effects of different remifentanil target concentrations on MACBAR of sevoflurane in patients with liver dysfunction under carbon dioxide pneumoperitoneum stimulus: A randomized controlled trial

WHAT IS KNOWN AND OBJECTIVE

Remifentanil can effectively decrease the sevoflurane concentration to block sympathetic adrenergic response to CO₂ pneumoperitoneum stimulus,and liver dysfunction will significantly reduce the MAC_BAR (minimum alveolar concentration for blocking adrenergic response) of sevoflurane. However, the effects of different remifentanil concentrations on the MAC_BAR of sevoflurane in patients with liver dysfunction are unclear. The aim of this study was to observe the effects of different remifentanil concentrations by intravenous target-controlled infusion on the MAC_BAR of sevoflurane in patients with grade B liver dysfunction under carbon dioxide pneumoperitoneum stimulus.

METHODS

Seventy-five patients with grade B liver dysfunction undergoing elective laparoscopic surgery were selected, and randomly divided into three groups with remifentanil plasma target concentrations of 0 (group R₀ ), 1 (group R₁ ) and 2 (group R₂ ) ng/ml. Anaesthesia was induced by intravenous injection of propofol 2-3 mg/kg, remifentanil 2 μg/kg and cisatracurium 0.15 mg/kg. All groups were inhaled different concentrations of sevoflurane. The determination of sevoflurane MAC_BAR in each group was used a method of sequential-allocation technique, and venous blood samples were taken before and after the creation of carbon dioxide pneumoperitoneum to determine plasma adrenaline and noradrenaline concentrations.

RESULTS AND DISCUSSIONS

The MAC_BAR of sevoflurane in groups R₀ , R₁ and R₂ was 4.83%, 3.00% and 2.10%, respectively. The MAC_BAR of sevoflurane was significantly difference among the three groups. When a similar effect of MAC_BAR had achieved in each group, no significant differences were found in the changes of plasma adrenaline and noradrenaline concentrations before and after the creation of pneumoperitoneum. What is new and conclusion Target-controlled infusion of different concentrations of remifentanil can reduce sevoflurane MAC_BAR during pneumoperitoneum stimulation in patients with liver dysfunction in some degree. However, the changes of plasma adrenaline and noradrenaline concentrations are consistent in the three groups when patient's stress response was inhibited at the same degree.

Protective role of dexmedetomidine against sevoflurane-induced postoperative cognitive dysfunction via the microRNA-129/TLR4 axis

The involvement of Dexmedetomidine (Dex) has been indicated in postoperative cognitive dysfunction (POCD), while the mechanism is not well characterized. This study estimated the mechanism of Dex in POCD. Rats were anesthetized with sevoflurane (SEV) to evoke POCD and then subjected to Morris water maze test to detect the cognitive and behavioral function. Then, the damage of hippocampus and cortex, and apoptosis and activity of neurons were examined. Microarray analysis was performed to screen out the differentially expressed microRNAs (miRs) in rats after Dex treatment. The cognitive and behavioral functions and neuronal activity of rats were detected after miR-129 antagomir injection. The target of miR-129 was predicted. The levels of TLR4 and NF-κB p65 in hippocampus and cortex were measured. Dex treatment alleviated SEV-induced behavior and cognitive impairments in rats, promoted neuronal activity and hindered neuronal apoptosis. After treatment with Dex, miR-129 expression was elevated in brain tissues, and the neuroprotection of Dex on POCD rats was partially annulled after injection of miR-129 antagomir. Furthermore, miR-129 targeted TLR4 and prevented the phosphorylation of NF-κB p65. In summary, Dex ameliorated SEV-induced POCD by elevating miR-129 and inhibiting TLR4 and NF-κB p65 phosphorylation. This study may shed new lights on POCD treatment.

Neonatal Sevoflurane Exposure Impairs Learning and Memory by the Hypermethylation of Hippocampal Synaptic Genes

Sevoflurane anesthesia is widely used in pediatric patients. Clinical studies report memory impairment in those exposed to general anesthesia early in life. DNA methylation is essential for the modulation of synaptic plasticity through regulating the transcription of synaptic genes. Therefore, we tested whether neonatal sevoflurane exposure affects learning and memory underlying the hippocampal DNA methylation of synaptic genes. Male Sprague-Dawley rats were exposed to 3% sevoflurane or air for 2 h daily from postnatal day 7 (P7) to P9. 5-aza-2-deoxycytidine (5-AZA), an inhibitor of DNA methyltransferases (DNMTs), was intraperitoneally injected 30 min before sevoflurane or air exposure on P7-9. The rats were euthanized 6, 12, 24 h, and 28 days after the last sevoflurane exposure, followed by the determination of global and gene-specific DNA methylation. The expression of synaptic proteins and synaptic density and the transcription of Dnmts and ten eleven translocations (Tets) in the hippocampus were measured. The ability of learning and memory was assessed using Morris water maze, novel object recognition, and intruder tests. Repeated neonatal sevoflurane exposure impaired cognitive, social, and spatial memory. The memory impairment was associated with the increased Dnmt1, Dnmt3a, and 5-methylcytosine level and the decreased Tet1 and 5-hydromethylcytosine level. Sevoflurane subsequently induced hypermethylation of Shank2, Psd95, Syn1, and Syp gene and down-regulated the expression of synaptic proteins, which finally led to the decrease of synaptic density in a time-dependent manner. Notably, 5-AZA pretreatment ameliorated learning and memory in sevoflurane-treated rats. In conclusion, neonatal exposure to sevoflurane can impair learning and memory through DNA methylation of synaptic genes.

Effects of different sufentanil target concentrations on the MACBAR of sevoflurane in patients with carbon dioxide pneumoperitoneum stimulus

BACKGROUND

This study aims to observe the effects of different target controlled plasma sufentanil concentrations on the minimum alveolar concentration (MAC) of sevoflurane for blocking adrenergic response (BAR) in patients undergoing laparoscopic cholecystectomy with carbon dioxide pneumoperitoneum stimulation.

METHODS

Eighty-five patients undergoing laparoscopic cholecystectomy, aged 30-65 years, with American Society of Anesthesiologists physical status I-II, were enrolled in this study. All the patients were randomly divided into 5 groups (S₀, S₁, S₂, S₃, S₄) with different sufentanil plasma target concentration (0.0, 0.1, 0.3, 0.5, 0.7 ng ml^- 1). Anesthesia was induced by inhalation of 8% sevoflurane in 100% oxygen, and 0.6 mg kg^- 1 of rocuronium was intravenously injected to facilitate the insertion of a laryngeal mask airway. The end-tidal sevoflurane concentration and sufentanil plasma target concentration were adjusted according to respective preset value in each group. The hemodynamic response to pneumoperitoneum stimulus was observed after the end-tidal sevoflurane concentration had been maintained stable at least for 15 min. The MAC_BAR of sevoflurane was measured by a sequential method. Meanwhile, epinephrine (E) and norepinephrine (NE) concentrations in the blood were also determined before and after pneumoperitoneum stimulus in each group.

RESULTS

When the method of independent paired reversals was used, the MAC_BAR of sevoflurane in groups S₀, S₁, S₂, S₃, S₄ was 5.333% (confidence interval [CI] 95%: 5.197-5.469%), 4.533% (95% CI: 4.451-4.616%), 2.861% (95% CI: 2.752-2.981%), 2.233% (95% CI: 2.142-2.324%) and 2.139% (95% CI: 2.057-2.219%), respectively. Meanwhile, when the isotonic regression analysis was used, the MAC_BAR of sevoflurane in groups S₀, S₁, S₂, S₃, S₄ was 5.329% (95% CI: 5.321-5.343%), 4.557% (95% CI: 4.552-4.568%), 2.900% (95% CI: 2.894-2.911%), 2.216% (95% CI: 2.173-2.223%) and 2.171% (95% CI: 2.165-2.183%), respectively. The MAC_BAR was not significantly different between groups S₃ and S₄ when using 0.5 and 0.7 ng ml^- 1 of sufentanil plasma target concentrations. No significant difference was found in the change of E or NE concentration between before and after pneumoperitoneum stimulation in each group.

CONCLUSIONS

The MAC_BAR of sevoflurane can be decreased with increasing sufentanil plasma target concentrations. A ceiling effect of the decrease occurred at a sufentanil plasma target concentration of 0.5 ng ml^- 1. When the sympathetic adrenergic response was inhibited in half of the patients to pneumoperitoneum stimulation in each group, the changes of E and NE concentrations showed no significant differences.

TRIAL REGISTRATION

The study was registered at http://www.chictr.org.cn ( ChiCTR1800015819 , 23, April, 2018).

High‑fat treatment prevents postoperative cognitive dysfunction in a hyperlipidemia model by protecting the blood‑brain barrier via Mfsd2a‑related signaling

Damage to the blood-brain barrier (BBB) resulting from systemic inflammation caused by surgical trauma is associated with cognitive dysfunction, and individuals with hyperlipidemia are more sensitive to such impairment. The present study was designed to ascertain whether dexmedetomidine (Dex) treatment could reduce the incidence of cognitive dysfunction following surgery in a hyperlipidemia model. Hyperlipidemia was induced in Sprague-Dawley rats (male, 6–7 months old) by consuming a high-fat diet, and rats were divided into three groups (n=10 each) and underwent: exploratory laparotomy to introduce surgical trauma (surgery group), laparotomy and Dex treatment (surgery+Dex group), or sham surgery (sham group). Learning, memory and exploration behavior were assessed using the Morris water maze. Concentrations of tumor necrosis factor (TNF)-α and interleukin (IL)-1β, were determined by enzyme-linked immunosorbent assay. BBB permeability was assessed by Evans blue staining. Relative major facilitator superfamily domain-containing protein 2 (Mfsd2a) mRNA expression was determined by quantitative PCR. In the Morris water maze test, the time and distance ratio for the surgery group was significantly lower than those of the sham and surgery+Dex groups (P<0.05). In addition, the TNF-α concentrations in the sham and surgery+Dex groups were lower than that in the surgery group (P<0.05 on days 1 and 3). Evans Blue staining was increased in the surgery group on day 1 (P<0.01). Mfsd2a mRNA expression was higher in the sham and surgery+Dex groups compared with that noted in the surgery group (P<0.05). In conclusion, Dex treatment decreased the incidence of cognitive dysfunction following surgical trauma in a hyperlipidemia rat model. We demonstrated that Dex stabilized BBB integrity through increased Mfsd2a gene expression.