Protective role of protocatechuic acid in sevoflurane-induced neuron apoptosis, inflammation and oxidative stress in mice

Sevoflurane causes cognitive impairment by inducing iron deficiency and inhibiting the proliferation of neural precursor cells in infant mice

AIMS

Numerous studies on animals have shown that exposure to general anesthetics in infant stage may cause neurocognitive impairment. However, the exact mechanism is not clear. The dysfunction of iron metabolism can cause neurodevelopmental disorders. Therefore, we investigated the effect of iron metabolism disorder induced by sevoflurane (Sev) on cognitive function and the proliferation of neural precursor cells (NPCs) and neural stem cells (NSCs) in infant mice.

METHODS

C57BL/6 mice of postnatal day 14 and neural stem cells NE4C were treated with 2% Sev for 6 h. We used the Morris water maze (MWM) to test the cognitive function of infant mice. The proliferation of NPCs was measured using bromodeoxyuridine (BrdU) label and their markers Ki67 and Pax6 in infant brain tissues 12 h after anesthesia. Meanwhile, we used immunohistochemical stain, immunofluorescence assay, western blot, and flow cytometer to evaluate the myelinogenesis, iron levels, and cell proliferation in cortex and hippocampus or in NE4C cells.

RESULTS

The results showed that Sev significantly caused cognitive deficiency in infant mice. Further, we found that Sev inhibited oligodendrocytes proliferation and myelinogenesis by decreasing MBP and CC-1 expression and iron levels. Meanwhile, Sev also induced the iron deficiency in neurons and NSCs by downregulating FtH and FtL expression and upregulating the TfR1 expression in the cortex and hippocampus, which dramatically suppressed the proliferation of NSCs and NPCs as indicated by decreasing the colocalization of Pax6+ and BrdU+ cells, and caused the decrease in the number of neurons. Interestingly, iron supplementation before anesthesia significantly improved iron deficiency in cortex and hippocampus and cognitive deficiency induced by Sev in infant mice. Iron therapy inhibited the decrease of MBP expression, iron levels in neurons and oligodendrocytes, and DNA synthesis of Pax6+ cells in hippocampus induced by Sev. Meanwhile, the number of neurons was partially recovered in hippocampus.

CONCLUSION

The results from the present study demonstrated that Sev-induced iron deficiency might be a new mechanism of cognitive impairment caused by inhaled anesthetics in infant mice. Iron supplementation before anesthesia is an effective strategy to prevent cognitive impairment caused by Sev in infants.

Phoenixin-20 ameliorates Sevoflurane inhalation-induced post-operative cognitive dysfunction in rats via activation of the PKA/CREB signaling

Post-operative cognitive dysfunction (POCD) is a common complication after surgery due to the usage of anesthetics, such as Sevoflurane, which severely impacts the life quality of patients. Currently, the pathogenesis of Sevoflurane-induced POCD has not been fully elucidated but is reportedly involved with oxidative stress (OS) injury and aggravated inflammation. Phoenixin-20 (PNX-20) is a PNX peptide consisting of 20 amino acids with promising inhibitory effects on OS and inflammation. Herein, we proposed to explore the potential protective function of PNX-20 on Sevoflurane inhalation-induced POCD in rats. Sprague-Dawley (SD) rats were treated with 100 ng/g PNX-20 for 7 days with or without pre-inhalation with 2.2% Sevoflurane. Markedly increased escape latency and decreased time in the target quadrant in the Morris water maze (MWM) test, and aggravated pathological changes and apoptosis in the hippocampus tissue were observed in Sevoflurane-treated rats, which were markedly attenuated by PNX-20. Furthermore, the aggravated inflammation and OS in the hippocampus observed in Sevoflurane-treated rats were notably abolished by PNX-20. Moreover, the brain-derived neurotrophic factor (BDNF), protein kinase A (PKA), and phospho-cAMP response element binding protein/cAMP response element binding protein (p-CREB/CREB) levels were markedly decreased in Sevoflurane-treated rats, which were memorably increased by PNX-20. Our results indicated that PNX-20 ameliorated Sevoflurane inhalation-induced POCD in rats via the activation of PKA/CREB signaling, which might supply a new treatment approach for POCD.

Exogenous recombinant Hsp70 attenuates sevoflurane anesthesia-induced cognitive dysfunction in aged mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a severe postoperative neurological sequela in elderly patients, and there is currently no standard treatment for POCD. In this study, whether recombinant human heat shock protein 70 (rHsp70) could alleviate sevoflurane-induced cognitive impairment in aged mice is investigated.

METHODS

To determine the prophylactic effect of rHsp70 in sevoflurane-induced cognitive dysfunction, aged mice were pretreated with different concentrations of rHsp70 (29.4, 58.8, and 117.6 μg/kg; intranasal injected; N = 12) every day for 1 week; then, 3% sevoflurane was utilized to anesthetize the aged mice. Cognitive function, neurotoxicity, and serum and hippocampal Hsp70 levels in aged mice undergoing sevoflurane anesthesia were assessed by the Morris water maze test and enzyme-linked immunosorbent assay. The effects of rHsp70 on inflammatory response were assessed by proinflammatory cytokine production and nuclear factor-κB (NF-κB) activation assays.

RESULTS

We found that aged mice exposed to sevoflurane showed reduced learning and memory ability and reduced Hsp70 expression, which were both restored by rHsp70 pretreatment. RHsp70 also reversed sevoflurane-induced up-regulated Bax and Bcl-2 expression and interleukin-1, IL-6, and monocyte chemoattractant protein-1 overproduction. Finally, rHsp70 pretreatment suppressed sevoflurane-induced NF-κB activation. Our study indicated that rHsp70 was sufficient to suppress sevoflurane-induced cognitive decline and neurotoxicity.

CONCLUSION

Our important finding warrants further study on the clinical application of rHsp70 in elderly patients undergoing anesthesia.

Knockdown of UAF1 alleviates sevoflurane-induced cognitive impairment and neurotoxicity in rats by inhibiting pro-inflammatory signaling and oxidative stress

Evidence has shown that suppression of the activation of NLRP3 inflammasome could ameliorate surgery/sevoflurane (SEV)-induced post-operative cognitive dysfunction (POCD). However, the underlying mechanisms remain unclear. UAF1 acts as a binding partner of USP1, which inhibits the ubiquitination-mediated degradation of NLRP3, indicating that UAF1 may be implicated in POCD through regulating the NLRP3 inflammasome. Here, we studied the role of UAF1/NLRP3 in SEV-induced cognitive impairment and neurotoxicity in rats. Neonatal rats were randomly divided into control, SEV, SEV+AAV-shNC and SEV+AAV-shUAF1 (UAF1-downregulated) groups. Morris water maze (MWM) test was applied to assess cognitive impairment. TUNEL staining, qRT-PCR and ELISA were used to assess the apoptosis and inflammation markers, respectively. The levels of superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) were quantified to determine oxidative stress. The results showed that SEV treatment led to significant cognitive impairment, increased apoptosis in hippocampal tissues, upregulation of MDA and inflammatory factors (TNF-α, IL-1β, IL-18), as well as a decrease in SOD and CAT levels. All of the above observations were reversed by UAF1 downregulation. Furthermore, depletion of UAF1 neutralized SEV-mediated increase in p-NLRP3, p-IκBα and p-p65 levels. Altogether, the current study demonstrated that knockdown of UAF1 could alleviate SEV-induced cognitive impairment and neurotoxicity in rats by inhibiting pro-inflammatory signaling and oxidative stress.

Long noncoding RNA BACE1-antisense transcript plays a critical role in Parkinson's disease via microRNA-214-3p/Cell death-inducing p53-target protein 1 axis

This study aimed to analyze the function and latent mechanism of long noncoding RNA BACE1-antisense transcript (lncRNA BACE1-AS) in MPP⁺-induced SH-SY5Y cells. SH-SY5Y cells were cultivated in 1 mM MPP⁺ for 24 h to establish Parkinson’s disease (PD) model in vitro. TargetScan and luciferase reporter assay were conducted to predict and verify the interaction between microRNA (miR)-214-3p and CDIP1 (Cell death-inducing p53-target protein 1). Cell viability, lactate dehydrogenase (LDH) release, and cell apoptosis were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT), LDH, and flow cytometer. The secretion of inflammatory factors and representative biomarkers of oxidative stress, including reactive oxygen species (ROS) and superoxide dismutase (SOD) were assessed using enzyme-linked immunosorbent assay (ELISA) and specific assay kits. Results suggested that lncRNA BACE1-AS was over-expressed and miR-214-3p was under-expressed in MPP⁺-stimulated SH-SY5Y cells. Further analyses revealed that MPP⁺ inhibited cell viability; enhanced cell apoptosis, Cleaved Caspase-3 expression and Cleaved Caspase-3/GAPDH ratio; induced oxidative stress and inflammation in SH-SY5Y cells were inhibited by lncRNA BACE1-AS-siRNA transfection; and all these inhibitions were reversed by miR-214-3p inhibitor. In addition, we found that CDIP1 was directly targeted by miR-214-3p and up-regulated in MPP⁺-stimulated SH-SY5Y cells. Further functional assays suggested that CDIP1-plasmid reversed the effects of miR-214-3p mimic on MPP⁺-stimulated SH-SY5Y cells. In conclusion, lncRNA BACE1-AS regulates SH-SY5Y cell proliferation, apoptosis, inflammatory response, and oxidative stress through direct regulation of miR-214-3p/CDIP1 signaling axis, and could be a potential candidate associated with the diagnosis and treatment of PD.

ATPase Inhibitory Factor 1 Is Critical for Regulating Sevoflurane-Induced Microglial Inflammatory Responses and Caspase-3 Activation

Postoperative delirium (POD) is one of the most important complications after surgery with general anesthesia, for which the neurotoxicity of general anesthetics is a high-risk factor. However, the mechanism remains largely unknown, which also hinders the effective treatment of POD. Here, we confirmed that a clinical concentration of the general anesthetic sevoflurane increased the expression of inflammatory factors and activated the caspase-3 by upregulating ATPase inhibitory factor 1 (ATPIF1) expression in microglia. Upregulation of ATPIF1 decreased the synthesis of ATP which is an important signaling molecule secreted by microglia. Extracellular supplementation with ATP attenuated the microglial inflammatory response and caspase-3 activation caused by sevoflurane or overexpression of ATPIF1. Additionally, the microglial inflammatory response further upregulated ATPIF1 expression, resulting in a positive feedback loop. Animal experiments further indicated that intraperitoneal injection of ATP significantly alleviated sevoflurane anesthesia-induced POD-related anxiety behavior and memory damage in mice. This study reveals that ATPIF1, an important protein regulating ATP synthesis, mediates sevoflurane-induced neurotoxicity in microglia. ATP supplementation may be a potential clinical treatment to alleviate sevoflurane-induced POD.

Inhibitive Effect of Luteolin on Sevoflurane-Induced Neurotoxicity through Activation of the Autophagy Pathway by HMOX1

Luteolin is a flavone compound occurring in a variety of medicinal plants, which is reported to have neuroprotective properties. In this study, we aimed to explore the effects of luteolin in alleviating sevoflurane-induced neurotoxicity. GeneCards and Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform were employed to screen luteolin, sevoflurane, and neurotoxicity-related genes. Subsequently, we isolated primary neurons from the hippocampus of 1-day-old C57BL/6J mice and tested for cytotoxicity after treatment of different concentrations of luteolin. Next, we measured the expression of apoptosis by flow cytometry and assessed inflammation-related factors, including heme oxygenase-1 expression detected by immunohistochemical staining and neuronal apoptosis. Finally, water maze, open field, and fear conditioning tests were conducted to observe the interaction between luteolin and sevoflurane in cognitive impairment of mice. Luteolin had the lowest cytotoxicity at concentrations of 30 or 60 μg/mL; we selected 30 μg/mL for drug administration experiments in vitro. Luteolin inhibited sevoflurane-induced neuronal apoptosis and inflammatory responses through the autophagic pathway and thus ameliorated sevoflurane-induced cognitive impairment in mice. Mechanistically, luteolin up-regulated heme oxygenase-1 expression, which activated the autophagy pathway in vitro. This was confirmed by subsequent histological experiments in mice and behavioral results showing rescue cognitive impairment. Our findings uncovered an inhibitory role of luteolin in sevoflurane-induced neuronal apoptosis and inflammatory response through activation of autophagy arising from up-regulation of heme oxygenase-1, thereby alleviating sevoflurane-induced cognitive impairment in mice.

MicroRNA-1297 suppressed the Akt/GSK3 signaling pathway and stimulated neural apoptosis in an in vivo sevoflurane exposure model

Objective

Common inhalation anesthetics used for clinical anesthesia (such as sevoflurane) may induce nerve cell apoptosis during central nervous system development. Furthermore, anesthetics can produce cognitive impairments, such as learning and memory impairments, that continue into adulthood. However, the precise mechanism remains largely undefined. We aimed to determine the function of microRNA-1297 (miR-1297) in sevoflurane-induced neurotoxicity.

Methods

Reverse transcription-polymerase chain reaction assays were used to analyze miR-1297 expression in sevoflurane-exposed mice. MTT and lactate dehydrogenase (LDH) assays were used to measure cell growth, and neuronal apoptosis was analyzed using flow cytometry. Western blot analyses were used to measure PTEN, PI3K, Akt, and GSK3β protein expression.

Results

In sevoflurane-exposed mice, miR-1297 expression was up-regulated compared with the control group. MiR-1297 up-regulation led to neuronal apoptosis, inhibition of cell proliferation, and increased LDH activity in the in vitro model of sevoflurane exposure. MiR-1297 up-regulation also suppressed the Akt/GSK3β signaling pathway and induced PTEN protein expression in the in vitro model. PTEN inhibition (VO-Ohpic trihydrate) reduced PTEN protein expression and decreased the effects of miR-1297 down-regulation on neuronal apoptosis in the in vitro model.

Conclusion

Collectively, the results indicated that miR-1297 stimulates sevoflurane-induced neurotoxicity via the Akt/GSK3β signaling pathway by regulating PTEN expression.