Notoginsenoside R1 attenuates sevoflurane-induced neurotoxicity

Notoginsenoside R1 attenuates bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway

Bupivacaine, a common amide local anesthetic, can provide effective analgesia or pain relief but can also cause neurotoxicity, which remains a mounting concern in clinic and animal care. However, the precise underlying mechanisms have not been fully elucidated. A natural compound, notoginsenoside R1 (NG-R1) has been reported to exhibit a neuroprotective role in stress conditions. In this study, we explored the function and mechanism of NG-R1 in alleviating bupivacaine-induced neurotoxicity in mouse hippocampal neuronal (HT-22) and mouse neuroblastoma (Neuro-2a) cell lines. Our results exhibited that NG-R1 treatment can significantly rescue the decline of cell survival induced by bupivacaine. Tunel staining and western blotting showed that NG-R1 could attenuate BPV‑induced cell apoptosis. Besides, we focused on Mcl1 as a potential target as it showed opposite expression tendency in response to NG-R1 and bupivacaine exposure. Mcl1 knockdown blocked the inhibitory effect of NG-R1 on cell apoptosis against bupivacaine treatment. Intriguingly, we found that NG-R1 can upregulate Mcl1 transcription by activating Stat3 and promote its nuclear translocation. In addition, NG-R1 can also promote Jak1 phosphorylation and docking analysis provide a predicted model for interaction between NG-R1 and phosphorylated Jak1. Taken together, our results demonstrated that NG-R1 can attenuate bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway.

Circular RNA DLGAP4 alleviates sevoflurane-induced neurotoxicity by regulating miR-9-5p/Sirt1/BDNF pathway

BACKGROUND

Sevoflurane is a widely used anesthetic in infants. However, long and repeated exposure to this drug can cause developmental neurotoxicity. This study aimed to investigate the role and mechanism of circular RNA DLGAP4 (circDLGAP4) in sevoflurane-induced neurotoxicity.

METHODS

Neonatal mice and mouse hippocampal neuronal cell line HT22 were used to construct sevoflurane-induced nerve injury models. The role of circDLGAP4 in sevoflurane-induced neurotoxicity was evaluated by gain-and/or loss-of-function methods. Pathological alterations in hippocampus were analyzed by hematoxylin-eosin and Tunel staining. Cell injury was assessed by cell viability and apoptosis, which was detected by CCK-8 and flow cytometry. The expression of circDLGAP4 and miR-9-5p was determined by real-time PCR. Sirt1 and BDNF levels were measured by Western blot. Productions of TNF-α and IL-6 were examined by ELISA. Dual-luciferase reporter assay and/or RNA pull-down assay were used to confirm the direct binding among circDLGAP4, miR-9-5p, and Sirt1. Rescue experiments were used to further verify the mechanism of circDLGAP4.

RESULTS

CircDLGAP4 expression was decreased by sevoflurane both in vivo and in vitro. Overexpression of circDLGAP4 elevated cell viability, reduced apoptosis and levels of TNF-α and IL-6, while circDLGAP4 knockdown showed the opposite effects in sevoflurane-induced HT22 cells. Mechanically, circDLGAP4 functioned via directly binding to and regulating miR-9-5p, followed by targeting the Sirt1/BDNF pathway. Additionally, circDLGAP4 upregulation relieved sevoflurane-induced nerve injury, reduced levels of TNF-α, IL-6 and miR-9-5p, but increased the expression of Sirt1 and BDNF in hippocampus.

CONCLUSIONS

Our studies found that circDLGAP4 relieved sevoflurane-induced neurotoxicity by sponging miR-9-5p to regulate Sirt1/BDNF pathway.

Natural products for the treatment of neurodegenerative diseases

BACKGROUND

Neurodegenerative diseases are among the most common diseases in older adults worldwide. Alzheimer's disease (AD) and Parkinson's disease (PD) are two of the most common neurodegenerative diseases, and are accompanied by cerebral cortical atrophy, neuronal loss, protein accumulation, and excessive accumulation of metal ions. Natural products exhibit outstanding performance in improving cerebral circulatory disorders, promoting cerebral haematoma absorption, repairing damaged nerve tissue, and improving damaged nerve function. In recent years, studies have shown that neuroinflammatory mechanisms and signalling pathways closely related to the occurrence and development of neurological diseases include microglial activation, nuclear factor-κB (NF-κB) pathway, mitogen activated protein kinases (MAPK) pathway, reactive oxygen pathway, nucleotide binding oligomerisation domain-like receptor protein3 (NLRP3) inflammasomes, toll-like receptor4 (TLR4) pathway, nuclear factor erythroid 2-related factor 2 (Nrf2)/hemeoxygenase-1 (HO-1) pathway, phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway, and intestinal flora. Therefore, this study considered the mechanism of neurological diseases as the starting point to review the mechanism of action of natural products in the prevention and treatment of AD and PD in recent years to provide a theoretical basis for clinical prevention and treatment.

AIM

Natural products are a promising source of novel lead structures that have long been used to treat various nervous system diseases.

METHODOLOGY

This review collected literature on neurological diseases and natural products from 2012 to 2022, which were mainly searched through databases such as ScienceDirect, Springer, PubMed, SciFinder, China National Knowledge Infrastructure (CNKI), Wanfang, Google Scholar, and Baidu Academic. The following keywords were searched: neurological disorders, natural products, signalling pathway, mechanism of action.

RESULTS

This review summarises the pathogenesis of degenerative neurological diseases, recent findings on natural products used in neurodegenerative diseases, and the molecular mechanisms underlying these effects.

Metformin attenuates sevoflurane-induced neurogenesis damage and cognitive impairment: involvement of the Nrf2/G6PD pathway

Anesthetics such as sevoflurane are commonly administered to infants and children. However, the possible neurotoxicity caused by prolonged or repetitive exposure to it should be a concern. The neuroprotective effects of metformin are observed in many models of neurological disorders. In this study, we investigated whether metformin could reduce the developmental neurotoxicity induced by sevoflurane exposure in neonatal rats and the potential mechanism. Postnatal day 7 (PND 7) Sprague-Dawley rats and neural stem cells (NSCs) were treated with normal saline or metformin before sevoflurane exposure. The Morris water maze (MWM) was used to observe spatial memory and learning at PND 35-42. Immunofluorescence staining was used to detect neurogenesis in the subventricular zone (SVZ) of the lateral ventricle and the subgranular zone (SGZ) of the dentate gyrus at PND 14. MTT assays, immunofluorescence staining, and TUNEL staining were used to assess the viability, proliferation, differentiation, and apoptosis of NSCs. Western blotting and ELISA were used to assess the protein expression of cleaved caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and glucose-6-phosphate dehydrogenase (G6PD) pathway-related molecules. Exposure to sevoflurane resulted in late cognitive defects, impaired neurogenesis in both the SVZ and SGZ, reduced NSC viability and proliferation, increased NSC apoptosis, and decreased protein expression of G6PD in vitro. Metformin pretreatment attenuated sevoflurane-induced cognitive functional decline and neurogenesis inhibition. Metformin pretreatment also increased the protein expression of Nrf2 and G6PD. However, treatment with the Nrf2 inhibitor, ML385 or the G6PD inhibitor, dehydroepiandrosterone (DHEA) reversed the protective effect of metformin on sevoflurane-induced NSC damage in vitro. Our findings suggested that metformin could reduce sevoflurane-induced neurogenesis damage and neurocognitive defects in the developing rat brain by influencing the Nrf2/G6PD signaling pathways.

Activated AMPK-mediated glucose uptake and mitochondrial dysfunction is critically involved in the glutamate-induced oxidative injury in HT22 cell

BACKGROUND

Accumulation of glutamate damages neurons via the reactive oxygen species (ROS) injury, which was involved in the development of neurodegenerative diseases. However, the mechanism of neuronal oxidative stress damage caused by glutamate and the intervention targets still needs to be further studied. This study explored whether 5' adenosine monophosphate-activated protein kinase (AMPK)-induced glucose metabolic and mitochondrial dysfunction were related to glutamate-dependent ROS injury of the neuron.

METHODS

Neuronal oxidative stress injury was induced by glutamate treatment in HT-22 cells. Western blotting was used to evaluate the phosphorylation of the AMPK. The XF24 Flux Analyzer was used to measure the effect of glutamate and Compound C (a well-known pharmacological inhibitor of AMPK phosphorylation) on the cellular oxygen consumption rate (OCR) of HT-22 cells. Glucose uptake, intracellular ROS, mitochondrial potential, apoptosis and cell viability were quantified using biochemical assays.

RESULTS

Glutamate caused the phosphorylation of AMPK and subsequently promoted the glucose uptake. Furthermore, AMPK-mediated glucose uptake enhanced OCR and increased the intracellular ROS levels in neurons. The pharmacological inhibition of AMPK phosphorylation by Compound C attenuated glutamate-induced toxicity in HT22 cells by regulating the glucose uptake/mitochondrial respiration/ROS pathway.

CONCLUSIONS

The AMPK phosphorylation/glucose uptake/mitochondrial respiration/ROS pathway was involved in glutamate-induced excitotoxic injury in HT22 cells. The inhibition of AMPK phosphorylation may be a potential target for the development of therapeutic agents for treating the glutamate-induced neurotoxicity.

Echinatin mitigates sevoflurane-induced hippocampal neurotoxicity and cognitive deficits through mitigation of iron overload and oxidative stress

CONTEXT

Sevoflurane (Sev) is a commonly used surgical anaesthetic; it has neurotoxic effects on the brain. Echinatin (Ech) is reported to have anti-inflammatory and antioxidant activity.

OBJECTIVE

This research confirms the effect of Ech on Sev-induced neurotoxicity and cognitive deficits.

MATERIALS AND METHODS

Primary rat hippocampal neurons were treated with 4.1% Sev for 6 h in the presence of Ech (5, 10, and 20 μM) or vehicle, followed by a further 42 h of culture. Male Sprague-Dawley aged rats were divided into 6 groups (n = 6): control, Sev, Sev + Ech (20 mg/kg;), Sev + Ech (40 mg/kg), and Sev + Ech (80 mg/kg). Rats were intraperitoneally injected with Ech or vehicle 1 h before Sev exposure (2% Sev for 5 h).

RESULTS

We found that Ech (5, 10, and 20 μM) elevated cell viability (1.29-, 1.51-, 1.68-fold) but mitigated apoptosis (23.87% vs. 16.48%, 12.72%, 9.02%), oxidative stress, and ferroptosis in hippocampal neurons with Sev treatment. Ech activated the Nrf2 expression in Sev-induced in vitro and in vivo models of anaesthetic neurotoxicity. Ech also weakened neurotoxicity in hippocampal neurons with Sev treatment by increasing Nrf2 expression level. Moreover, Ech alleviated hippocampus neurons apoptosis (19.38% vs. 16.05%, 11.71%, 8.88%), oxidative stress, and ferroptosis in rats with Sev treatment. Ech improved Sev-induced cognitive deficits in rats.

CONCLUSIONS

Ech alleviates Sev-induced neurotoxicity and cognitive deficits by mitigation of ferroptosis and oxidative stress. Ech may be developed as a new promising therapeutic drug for treatment of cerebral nerve injury caused by surgical anaesthesia.

Global analysis of qualitative and quantitative metabolism of Notoginsenoside R1 in rat liver-brain-gut axis based on LC-IT-TOF/MS combing mMDF strategy

BACKGROUND

The metabolism study of active components for traditional Chinese medicine (TCM) in target organs is conducive to clarify the authentic active ingredients. Notoginsenoside R1 (NG-R1), one of the bioactive components of Panax notoginsenoside (PNS), is commonly acknowledged as the characteristic marker of PNS. However, the metabolism of NG-R1 in target organs has not been clarified yet due to the lack of robust technique and approach.

PURPOSE

The present study aimed to develop a reliable and efficient strategy and technology for revealing the qualitative and quantitative metabolism of active components of TCMs in target organs, and to clarify the biotransformation of NG-R1 in liver-brain-intestinal axis.

METHODS

The metabolic transformation of NG-R1 in the brain gut axis was investigated in the in vitro incubation system of fresh rat brain, liver homogenate, and intestinal flora. To quickly lock the target metabolites, we set the mass defect filter (MDF) in different ranges to screen metabolites with different molecular weight (MW). This strategy was defined as multi-stage MDF (mMDF). In addition, we performed relative quantitative analysis on all metabolites according to the peak area acquired by LC-IT-TOF/MS to overcome the challenge that metabolites are difficult to be quantified due to the lack of standards.

RESULTS

When MDF was set at 0.50 to 0.65 to screen metabolites with MW of 900 to 1200 Da, 6 novel metabolites were quickly found, and then identified as glucuronic acid binding, oxidation, dehydrogenation, methylation and hydrogenation products according to their LC and MS characteristics. When setting MDF at 0.42 - 0.52, 6 metabolites with MW of 600 to 900 Da were effectively screened and identified as Rg1, NG-R2, Rh1, Rg1+CH₂+2H and Rg1+CH₂. To screen the metabolites with MW of 300 to 600 Da, MDF was set at 0.25 - 0.42, and 4 novel metabolites were screened rapidly. The results of quantitative metabolism suggested that intestinal flora was the main metabolic site of NG-R1 in rat, and more than 60% of NG-R1 was converted to Rg1 by deglycosylation in the intestinal flora.

CONCLUSION

The mMDF strategy can significantly improve the research efficiency of qualitative metabolism of saponins. Although NG-R1 could be transformed into a variety of metabolites in rat liver and brain homogenate, it still existed mainly in prototype form. In the rat flora, NG-R1 mainly existed in the form of deglycosylated metabolite Rg1.

Sevoflurane exposure during the second trimester induces neurotoxicity in offspring rats by hyperactivation of PARP-1

RATIONALE

Fetal exposure to general anesthesia may cause noteworthy neurocognitive impairment, but the mechanisms are unclear.

OBJECTIVES

Our study designed to explore the potential mechanism of neurotoxicity in offspring rats after sevoflurane exposure to the pregnant rats during the second trimester.

METHODS

Pregnant rats (G14 day) were administrated with or without 3.5% sevoflurane, 40 mg/kg 3-aminobenzamide (3-AB), inhibitor of poly ADP ribose polymerase 1 (PARP-1), or 10 mg/kg TC-2153, inhibitor of striatal-enriched phosphatase 61 (STEP61). Afterwards, the effects on expression of β-tubulin (TUJ1), neurite outgrowth inhibitor A (Nogo-A), parthanatos-related and STEP61/proline-rich tyrosine kinase 2 (Pyk2) pathway-associated proteins, and reactive oxygen species (ROS) levels were examined by immunofluorescence staining, Western blot, and dihydroethidium (DHE) staining, respectively. Moreover, morphological changes in the hippocampal CA3 region and neuronal cell death were tested by glycine silver staining and TUNEL and immunofluorescence double staining, respectively. Furthermore, spatial learning and memory functions of rats on postnatal 28-33 days (PND 28-33) were evaluated by morris water maze (MWM).

RESULTS

Mid-pregnancy exposure to sevoflurane led to excessive PARP-1 activation, poly (ADP-ribose) (PAR) polymer accumulation, apoptosis-inducing factor (AIF) nuclear translocation, and Nogo-A accumulation. Besides, sevoflurane significantly inhibited neurite growth and increased cell death in the fetal rat brain. Additionally, sevoflurane activated STEP61/Pyk2 pathway and increased ROS levels. However, 3-AB or TC-2153 significantly alleviated cell death, promoted neurites growth, and improved sevoflurane-induced spatial learning and memory impairment.

CONCLUSION

This study proposes that sevoflurane exposure during the second trimester incudes neurotoxicity in offspring rats by hyperactivation of PARP-1 via STEP61/Pyk2 pathway.

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.

Biochanin A protects SH-SY5Y cells against isoflurane-induced neurotoxicity by suppressing oxidative stress and apoptosis

Biochanin A (BCA) is a natural organic O-methylated isoflavone with a variety of pharmacological effects, and has been reported to have neuroprotective properties. Here, we explored whether BCA protects neurocytes against isoflurane-induced neurotoxicity and investigated the underlying mechanism. Cell viability was tested by cell counting kit-8 and lactate dehydrogenase release assays. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and caspase-3/7 activity assays. Superoxide dismutase (SOD) and catalase (CAT) activities and levels of glutathione (GSH) and malondialdehyde (MDA) were measured to assess oxidative stress. Expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase (NQO1) was determined by western blotting. Treatment with BCA significantly attenuated the reduction of cell viability induced by isoflurane in SH-SY5Y cells. In addition, BCA treatment reversed isoflurane-induced SOD and CAT activity reduction, GSH level decline and MDA level increase. Isoflurane-induced apoptosis was also attenuated by treatment with BCA. The increase in nuclear Nrf2, HO-1 and NQO1 expression induced by isoflurane was amplified by treatment with BCA. These inhibitory effects of BCA on isoflurane-induced oxidative stress, viability reduction and cell apoptosis were attenuated in Nrf2 knockdown SH-SY5Y cells. Our findings indicate that BCA protects SH-SY5Y cells against isoflurane-induced neurotoxicity via inducing the Nrf2/ARE pathway.

Effects of notoginsenoside R1 on attenuating depressive behavior induced by chronic stress in rats through induction of PI3K/AKT/NF-κB pathway

Chronic unpredictable mild stress (CUMS) can cause a series of depressive symptoms in depression patients. Recently, notoginsenoside R1 (NGR1) has been reported to play crucial roles in the anti-inflammatory, antioxidant, and anti-apoptotic. However, the role and mechanisms of NGR1 in improving symptoms of depressive behavior remain unknown. Evaluating and identifying its value and exploring the mechanisms of NGR1 on CUMS-induced depressive behavior were the aims of this study. Here, rats were separated into five different groups and treated with or without different concentrations of the NGR1. Then, the body weight, sucrose preference rate, immobility time, crossing number, rearing number, and grooming number were determined to evaluate the effect of NGR1 on improving the depressive behavior of CUMS rats. Subsequently, the morphology of hippocampal neurons and protein expression of brain-derived neurotrophic factor in each group were examined by hematoxylin and eosin staining and western blot to show the neuroprotective effects of NGR1. Furthermore, the mRNA and protein expression of TNF-α, IL-6, and IL-1β were also detected by quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay to verify the anti-inflammatory effects of NGR1 on CUMS rats. In addition, the cell apoptosis-related proteins were examined to reveal that NGR1 can inhibit cell apoptosis in CUMS rats. Moreover, it was confirmed that NGR1 attenuated the symptoms of depressive behavior by mediated PI3K/Akt/NF-κB pathway. Together, this study shows that NGR1 improves depressive behavior induced by chronic stress in rats through activation of PI3K/AKT/NF-κB pathway.