Neurotoxicity In HT22 Cells Research Articles

Neuroprotective Effects of Ethanol Extract Polyscias guilfoylei (EEPG) Against Glutamate Induced Neurotoxicity in HT22 Cells.

Oxidative stress induced by glutamate is a significant contributor to neuronal cell damage and can lead to neurodegenerative diseases such as Alzheimer's, Huntington's, and ischemic brain injury. At the cellular level, oxidative stress increases Ca2+ ion influx and reactive oxygen species (ROS), which activate the MAPK signaling pathway. Additionally, the generation of ROS causes mitochondrial dysfunction, triggering apoptosis by promoting the translocation of AIF to the nucleus from the mitochondria. The neuroprotective potential of Polyscias guilfoylei has not yet been reported. Therefore, in this study, the ethanol extract of Polyscias guilfoylei (EEPG) was examined for its protective effect against oxidative cell damage caused by glutamate in neuronal cells. EEPG treatment increased the viability of HT22 cells exposed to high concentrations of glutamate. Cellular Ca2+ ion influx and ROS generation decreased with EEPG treatment in glutamate-treated HT22 cells. EEPG treatment inhibited MAPK activation and AIF nuclear translocation. In an in vivo study, EEPG attenuated brain cell death in an ischemic brain injury rat model. This study demonstrates the potential therapeutic effects of Polyscias guilfoylei in the treatment of ischemic brain injury.

Ethyl Acetate Fraction of Chestnut Honey Attenuates Scopolamine-Induced Cognitive Impairment in Mice and Glutamate-Induced Neurotoxicity in HT22 Cells.

Chestnut honey has various benefits, such as antioxidative, anti-inflammatory, immunomodulatory, antibacterial, and antiviral effects. However, the effects of chestnut honey or the ethyl acetate fraction of chestnut honey (EACH) on neurodegenerative diseases and their related cognitive impairment and neurotoxicity have not yet been established. Therefore, in this study, we investigated the mitigating effect of the EACH on scopolamine (SCO)-injected cognitive decline in mice and glutamate-exposed neurotoxicity in HT22 cells. EACH administration significantly reversed SCO-induced cognitive decline in mice, as demonstrated through the Morris water maze and passive avoidance tests. The EACH treatment showed a significant alleviation effect by recovering more than 80% of the cell viability decrease induced by glutamate exposure in the HT22 neuronal cell model. Furthermore, the EACH significantly reduced reactive oxygen species accumulation, lactate dehydrogenase release, mitochondrial depolarization, and neuronal apoptosis. The EACH regulated the level of apoptosis-related proteins, induced the nuclear translocation of nuclear factor-E2-related factor 2 (Nrf-2) and the expression of related antioxidant proteins, and induced the phosphorylation of tropomyosin-related kinase receptor B (TrkB)/cAMP-calcium response element-binding protein (CREB) and the expression of brain-derived neurotrophic factor. These data indicate that the EACH can prevent neurons from oxidative damage and improve cognitive dysfunction by activating Nrf-2 and TrkB/CREB signaling pathways. Therefore, the EACH demonstrates potential therapeutic value in mitigating oxidative stress-induced neurotoxicity, cognitive decline, and related neurodegenerative diseases.

FNDC5/Irisin mitigates high glucose-induced neurotoxicity in HT22 cell via ferroptosis.

Diabetes-induced neuropathy represents a major etiology of dementia, highlighting an urgent need for the development of effective therapeutic interventions. In this study, we explored the role of fibronectin type III domain containing 5 (FNDC5)/Irisin in mitigating hyperglycemia-induced neurotoxicity in HT22 cells and investigated the underlying mechanisms. Our findings reveal that high glucose conditions are neurotoxic, leading to reduced viability of HT22 cells and increased apoptosis. Furthermore, the elevated expression of the intracellular ferroptosis marker Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), along with increased levels of ferrous ions and malondialdehyde (MDA), suggests that high glucose conditions may induce ferroptosis in HT22 cells. FNDC5/Irisin treatment effectively mitigates high glucose-induced neurotoxicity and ferroptosis in HT22 cells. Mechanistically, FNDC5/Irisin enhances cellular antioxidant capacity, regulates ACSL4 expression, and improves intracellular redox status, thereby inhibiting ferroptosis and increasing HT22 cell survival under high-glucose conditions. These results highlight the neuroprotective potential of FNDC5/Irisin in high glucose environments, offering a promising avenue for developing treatments for diabetes-related neurodegenerative diseases.

Ellagic Acid Reduces Cadmium Exposure-Induced Apoptosis in HT22 Cells via Inhibiting Oxidative Stress and Mitochondrial Dysfunction and Activating Nrf2/HO-1 Pathway.

Exposure to cadmium sulfate (CdSO4) can lead to neurotoxicity. Nevertheless, the precise molecular mechanisms underlying this phenomenon remain unclear, and effective treatment strategies are scarce. This study explored the protective effects of ellagic acid (EA), a natural polyphenolic compound, against CdSO4 exposure-induced neurotoxicity in HT22 cells and the underlying molecular mechanisms. Our findings demonstrated that exposure of HT22 cells to CdSO4 resulted in apoptosis, which was effectively reversed by EA in a dose-dependent manner. EA supplementation also decreased reactive oxygen species (ROS) and mitochondrial ROS production, reduced malondialdehyde (MDA) levels, and restored the activities of superoxide dismutase (SOD) and catalase (CAT). Additionally, EA supplementation at 5-20 μM significantly counteracted Cd-induced the loss of mitochondrial membrane potential and the decrease of ATP and reduced the ratio of Bax/Bcl-2 and cleaved-caspase-3 protein expression. Furthermore, EA supplementation resulted in the upregulation of Nrf2 and HO-1 protein and mRNAs while simultaneously downregulating the phosphorylation of JNK and p38 proteins. The pharmacological inhibition of c-Jun N-terminal kinase (JNK) partially attenuated the activation of the Nrf2/HO-1 pathway induced by CdSO4 and exacerbated its cytotoxic effects. In conclusion, our findings suggest that ethyl acetate (EA) supplementation offers protective effects against CdSO4-induced apoptosis in HT22 cells by inhibiting oxidative stress and activating the Nrf2 signaling pathway. Furthermore, the activation of the JNK pathway appears to play a protective role in CdSO4-induced apoptosis in HT22 cells.

Neuroprotective mechanism of corydaline in glutamate-induced neurotoxicity in HT22 cells

Neuroprotective mechanism of corydaline in glutamate-induced neurotoxicity in HT22 cells

Therapeutic Potential of Traditional Oriental Medicines in Targeting Tau Pathology: Insights from Cell-free and Cell-based Screening.

Traditional Oriental Medicines (TOMs) formulated using a variety of medicinal plants have a low risk of side effects. In previous studies, five TOMs, namely Dangguijakyaksan, Hwanglyeonhaedoktang, Ukgansan, Palmijihwanghwan, and Jowiseungchungtang have been commonly used to treat patients with Alzheimer's disease. However, only a few studies have investigated the effects of these five TOMs on tau pathology. This study aimed to examine the effect of five TOMs on various tau pathologies, including post-translational modifications, aggregation and deposition, tau-induced neurotoxicity, and tau-induced neuroinflammation. Immunocytochemistry was used to investigate the hyperphosphorylation of tau induced by okadaic acid. In addition, the thioflavin T assay was used to assess the effects of the TOMs on the inhibition of tau K18 aggregation and the dissociation of tau K18 aggregates. Moreover, a water-soluble tetrazolium-1 assay and a quantitative reverse transcription polymerase chain reaction were used to evaluate the effects of the TOMs on tau-induced neurotoxicity and inflammatory cytokines in HT22 and BV2 cells, respectively. The five TOMs investigated in this study significantly reduced okadaic acid-induced tau hyperphosphorylation. Hwanglyeonhaedoktang inhibited the aggregation of tau and promoted the dissociation of tau aggregates. Dangguijakyaksan and Hwanglyeonhaedoktang attenuated tau-induced neurotoxicity in HT22 cells. In addition, Dangguijakyaksan, Hwanglyeonhaedoktang, Ukgansan, and Palmijihwanghwan reduced tauinduced pro-inflammatory cytokine levels in BV2 cells. Our results suggest that five TOMs are potential therapeutic candidates for tau pathology. In particular, Hwanglyeonhaedoktang showed the greatest efficacy among the five TOMs in cell-free and cell-based screening approaches. These findings suggest that Hwanglyeonhaedoktang is suitable for treating AD patients with tau pathology.

Arecoline induces neurotoxicity in HT22 cells via the promotion of endoplasmic reticulum stress and downregulation of the Nrf2/HO-1 pathway.

Arecoline, the predominant bioactive substance extracted from areca nut (AN), is the world's fourth most frequently used psychoactive material. Research has revealed that chewing AN can affect the central nervous system (CNS) and may lead to neurocognitive deficits that are possibly linked to the action of arecoline. However, the mechanism behind the neurotoxicity caused by arecoline remains unclear. This study aimed to investigate the neurotoxic effects of arecoline and its underlying mechanism. The results showed that arecoline caused cytotoxicity against HT22 cells in a dose-dependent manner and induced apoptosis by upregulating the expression of pro-apoptotic caspase and Bcl-2 family proteins. Furthermore, arecoline escalated intracellular reactive oxygen species (ROS) levels and Ca2+ concentration with increasing doses, thereby motivating endoplasmic reticulum stress (ERS) and ERS-associated apoptotic protein expression. Additionally, the study found that arecoline attenuates intracellular antioxidant defense by inhibiting the translocation of NF-E2-related factor-2 (Nrf2) into the nucleus and decreasing downstream Heme oxygenase-1 (HO-1) levels. The specific inhibitor Sodium 4-phenylbutyrate (4-PBA) can dramatically attenuate arecoline-mediated cell apoptosis and ERS-associated apoptotic pathway expression by blocking ERS. The antioxidant N-Acetylcysteine (NAC) also effectively reverses the arecoline-mediated increase of ERS-related apoptotic pathway protein levels by scavenging intracellular ROS accumulation. In conclusion, this study suggests that arecoline induces neurotoxicity in HT22 cells via ERS mediated by oxidative stress- and Ca2+ disturbance, as well as by downregulation of the Nrf2/HO-1 pathway.

Hydrogen sulfide antagonizes formaldehyde-induced ferroptosis via preventing ferritinophagy by upregulation of GDF11 in HT22 cells

Formaldehyde (FA) has neurotoxic characteristics and causes neurodegenerative disease. Our previous study demonstrated the neuroprotective effects of hydrogen sulfide (H2S) on FA-induced neurotoxicity in HT22 cells. Emerging evidence have supported that ferroptosis is involved in FA-induced neurotoxicity. To understand the mechanism of the protection of H2S against FA-induced neurotoxicity, this study explored the regulatory effect of H2S on FA-induced ferroptosis and the underlying mechanisms. We found that H2S (100, 200, and 400 μM, 30 min) reverses the ferroptosis induced by FA (100 μM, 24 h) in HT22 cells (a cell line of mouse hippocampal neurons), including decreases in free iron, reactive oxygen species (ROS), 4-hydroxy-2-trans-nominal (4-HNE), and malondialdehyde (MDA) contents, as well as an increase in glutathione (GSH) content. H2S (100, 200, and 400 μM, 30 min) also inhibited ferritinaphagy in FA-exposed HT22 cells, as evidenced by the downregulation of the ferritinophagy receptor nuclear receptor coactivator 4 (NCOA4) and microtubule-associated protein 1 light chain-3B (LC3B) as well as the upregulation of the main iron storage protein ferritin heavy chain 1 (FTH1) and p62. H2S (100, 200, and 400 μM, 30 min) also up-regulated the expression of growth differentiation factor-11 (GDF11) in FA-exposed HT22 cells. Furthermore, knockdown of GDF11 in HT22 cells cancelled the beneficial effects of H2S on FA-induced ferroptosis and ferritinaphagy. These data indicated that the protective mechanism underlying H2S-prevented neurotoxicity of FA is involved in alleviating FA-induced ferroptosis via inhibiting ferritinaphagy by upregulation of GDF11.

Protective effect of fermented aloe extract on glutamate-induced cytotoxicity in HT22 cells

ABSTRACT Excessive glutamate can cause oxidative stress in neuronal cells and this can significantly contribute to the etiology of neurodegenerative disease. The present study mainly aims to investigate that aloe extract (AE) and fermented aloe extract (FAE) could protect against glutamate-induced cytotoxicity by modulating oxidative stress. In this study, both AE and FAE showed potent neuroprotective activity by inhibiting ROS and Ca2+ concentration, increasing mitochondria membrane potential, and activating glutathione-related enzymes against glutamate-insulted neurotoxicity in HT22 cells. In addition, the neuroprotective activity of FAE was more potent than that of AE. HPLC analysis reveals that the chemical composition of FAE is different from that of AE. Especially, the contents of aloin A, aloin B and aloenin were higher in FAE than in AE. In conclusion, this study indicates that both AE and FAE may have effective neuroprotective activity in glutamate-insulted pathological conditions such as Alzheimer’s disease by managing oxidative stress.

Protective effects of berberine against β-amyloid-induced neurotoxicity in HT22 cells via the Nrf2/HO‐1 pathway

Neuronal apoptosis has been found to have a pivotal role in the course of Alzheimer’s disease (AD). Berberine (BBR), a potent antioxidant, occurs in plants such as Berberis, Phellodendron chinense, and Hydrastis canadensis. In this study, a neuronal apoptotic model was established in vitro using HT22 cells induced by Aβ25-35 to explore whether BBR contributes to protecting neurons against Aβ25-35-induced neurotoxicity, as well as its potential mechanisms. BBR was applied to HT22 cells for 1 h prior to exposing the cells to Aβ25-35 for 24 h. A CCK-8 assay was utilized to assess cell viability, and Annexin V − fluorescein isothiocyanate (FITC)/propidium iodide and Hoechst 33342 fluorescence staining were used to measure the rate of cell apoptosis. Existing scientific literature was also reviewed to further determine the effects of BBR on ROS production and mitochondrial function in HT22 cells. Furthermore, the expressions of proteins, including cytochrome C, cleaved caspase-3, p-p65, p65, and Nrf2/HO‐1 antioxidant axis were assessed by Western blotting. The data indicated that BBR markedly improved cell viability, inhibited apoptosis and intracellular ROS levels, improved mitochondrial membrane potentials, decreased the rate of p-p65/p65, cytochrome C, and cleaved caspase-3, and intensified the activity of Nrf2/HO‐1 antioxidants in HT22 cells. Overall, the findings indicated that BBR provides a certain level of neuroprotectiveness in HT22 cells exposed to Aβ25–35 via relieving oxidative stress, as well as by restraining the mitochondrial pathway of cellular apoptosis. In addition, the restraint of NF-κB activity and sensitization of the Nrf2/HO‐1 antioxidant axis, which together are intimately involved in the neuroprotection of BBR, may be possible mechanisms accounting for its effectiveness against Aβ25–35in vitro.

Cleistocalyx nervosum var. paniala Berry Promotes Antioxidant Response and Suppresses Glutamate-Induced Cell Death via SIRT1/Nrf2 Survival Pathway in Hippocampal HT22 Neuronal Cells.

Excessive glutamate neurotransmitters result in oxidative neurotoxicity, similar to neurodegeneration. An indigenous berry of Thailand, Cleistocalyx nervosum var. paniala (CNP), has been recognized for its robust antioxidants. We investigated the effects and mechanisms of CNP fruit extracts on antioxidant-related survival pathways against glutamate-induced neurotoxicity. The extract showed strong antioxidant capability and had high total phenolic and flavonoid contents, particularly resveratrol. Next, the protective effects of the CNP extract or resveratrol on the glutamate-induced neurotoxicity were examined in HT22 hippocampal cells. Our investigation showed that the pretreatment of cells with the CNP extract or resveratrol attenuated glutamate-induced neuronal death via suppression of apoptosis cascade by inhibiting the levels of cleaved- and pro-caspase-3 proteins. The CNP extract and resveratrol suppressed the intracellular ROS by increasing the mRNA expression level of antioxidant enzymes (SODs, GPx1, and CAT). We found that this extract and resveratrol significantly increased SIRT1 expression as a survival-related protein. Moreover, they also promoted the activity of the Nrf2 protein translocation into the nucleus and could bind to the promoter containing the antioxidant response element, inducing the expression of the downstream GPx1-antioxidant protein. Our data illustrate that the CNP extract and resveratrol inhibit apoptotic neuronal death via glutamate-induced oxidative neurotoxicity in HT22 cells through the activation of the SIRT1/Nrf2 survival mechanism.

Maf1 mitigates sevoflurane-induced microglial inflammatory damage and attenuates microglia-mediated neurotoxicity in HT-22 cells by activating the AMPK/Nrf2 signaling

BackgroundMaf1 has been found to play protective function against neuroinflammation and neuroapoptosis. This study seeks to explore whether and how Maf1 is involved in sevoflurane (Sev)-induced neuroinflammation and microglia-mediated neurotoxicity. MethodsqRT-PCR and western blot were used to detect the gene expression. ELISA was used to detect inflammatory factors. Cell viability was evaluated by using the Cell Counting Kit-8 kit. Neuroapoptosis was assessed with trhe Caspase-3 Assay Kit and the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) technique. ResultsMaf1 expression was downregulated in Sev-stimulated BV2 microglial cells. Maf1 overexpression down-regulates the expression of pro-inflammatory M1-type markers (CD86, iNOS, IFN-γ) and up-regulates the expression of anti-inflammatory M2-type markers (CD206, TGF-β, Arg-1), and Maf1 reduces the Sev-induced inflammatory response in BV2 cells. After Maf1 overexpression, the relative expression of p-AMPK/AMPK and nucleus-Nrf2 increased significantly in BV2 cells treated with Sev. Inhibition of AMPK/Nrf2 pathway by compound C reverses anti-inflammatory effect of Maf1 in Sev-stimulated BV2 cells. Compound C reverses the effect of Maf1 on microglia-mediated neurotoxicity in HT-22 hippocampal neuronal cells. ConclusionsMaf1 mitigates Sev-induced microglial inflammatory damage and attenuates microglia-mediated neurotoxicity by activating the AMPK/Nrf2 signaling.

Eriodictyol ameliorates cognitive dysfunction in APP/PS1 mice by inhibiting ferroptosis via vitamin D receptor-mediated Nrf2 activation

BackgroundAlzheimer’s disease (AD) is the most common type of neurodegenerative disease in the contemporary era, and it is still clinically incurable. Eriodictyol, a natural flavonoid compound that is mainly present in citrus fruits and some Chinese herbal medicines, has been reported to exert anti-inflammatory, antioxidant, anticancer and neuroprotective effects. However, few studies have examined the anti-AD effect and molecular mechanism of eriodictyol.MethodsAPP/PS1 mice were treated with eriodictyol and the cognitive function of mice was assessed using behavioral tests. The level of amyloid-β (Aβ) aggregation and hyperphosphorylation of Tau in the mouse brain were detected by preforming a histological analysis and Western blotting. HT-22 cells induced by amyloid-β peptide (1–42) (Aβ1–42) oligomers were treated with eriodictyol, after which cell viability was determined and the production of p-Tau was tested using Western blotting. Then, the characteristics of ferroptosis, including iron aggregation, lipid peroxidation and the expression of glutathione peroxidase type 4 (GPX4), were determined both in vivo and in vitro using Fe straining, Western blotting and qPCR assays. Additionally, the expression level of vitamin D receptor (VDR) and the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway were tested using Western blotting and qPCR assays. Afterward, HT-22 cells with VDR knockout were used to explore the potential mechanisms, and the relationship between VDR and Nrf2 was further assessed by performing a coimmunoprecipitation assay and bioinformatics analysis.ResultsEriodictyol obviously ameliorated cognitive deficits in APP/PS1 mice, and suppressed Aβ aggregation and Tau phosphorylation in the brains of APP/PS1 mice. Moreover, eriodictyol inhibited Tau hyperphosphorylation and neurotoxicity in HT-22 cells induced by Aβ1–42 oligomer. Furthermore, eriodictyol exerted an antiferroptosis effect both in vivo and in vitro, and its mechanism may be associated with the activation of the Nrf2/HO-1 signaling pathway. Additionally, further experiments explained that the activation of Nrf2/HO-1 signaling pathway by eriodictyol treatment mediated by VDR.ConclusionsEriodictyol alleviated memory impairment and AD-like pathological changes by activating the Nrf2/HO-1 signaling pathway through a mechanism mediated by VDR, which provides a new possibility for the treatment of AD.

Fraxetin suppresses reactive oxygen species-dependent autophagy by the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells.

Isoflurane, a common volatile anesthetic, has been widely used to provide general anesthesia in operations. However, exposure to isoflurane may cause widespread neurotoxicity in the developing animal brain. Fraxetin, a natural coumarin derivative extracted from the bark of Fraxinus rhynchophylla, possesses versatile pharmacological properties including anti-oxidative, anti-inflammatory, and neuroprotective effects. However, the effect and action mechanism of fraxetin on neurotoxicity induced by isoflurane are unknown. Reactive oxygen species (ROS) generation, cell viability, lactate dehydrogenase (LDH) release, and apoptosis were estimated by 2',7'-dichlorofluorescin-diacetate (DCFH-DA) staining, MTT, LDH release, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining assays, respectively. The protein levels of light chain 3 (LC3)-I, LC3-II, p62, protein kinase B (Akt), and phosphorylated Akt (p-Akt) were detected by western blot analysis. Isoflurane induced ROS, LDH release, apoptosis, and autophagy, but inhibited the viability in HT22 cells, which were overturned by fraxetin or ROS scavenger N-acetyl-L-cysteine. Fraxetin suppressed isoflurane-induced PI3K/Akt inactivation in HT22 cells. PI3K/Akt inactivation by LY294002 resisted the effects of fraxetin on isoflurane-induced autophagy and autophagy-modulated neurotoxicity in HT22 cells. In conclusion, fraxetin suppressed ROS-dependent autophagy by activating the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells.

Development of Bisindole-Substituted Aminopyrazoles as Novel GSK-3β Inhibitors with Suppressive Effects against Microglial Inflammation and Oxidative Neurotoxicity.

Development of glycogen synthase kinase-3β (GSK-3β) inactivation-centric agents with polypharmacological profiles is increasingly recognized as a promising therapeutic strategy against the multifactorial etiopathology of Alzheimer's disease (AD). In this respect, a series of disubstituted aminopyrazole derivatives were designed and synthesized as a new class of GSK-3β inhibitors. Most of these derivatives possess GSK-3β inhibitory activities with IC50 values in the micromolar ranges, among which bisindole-substituted aminopyrazole derivative 6h displayed moderate GSK-3β inhibition (IC50 = 1.76 ± 0.19 μM), and alleviative effects against lipopolysaccharide (LPS)-induced glial inflammation in BV-2 cells and glutamate-induced oxidative neurotoxicity in HT-22 cells. Further in vivo studies indicated that compound 6h had potent anti-inflammatory effect, by showing markedly reduced microglial activation and astrocyte proliferation in the brain of LPS-injected mice. Overall, the simultaneous modulation of 6h on multiple dysfunctions of disease network highlights this structural distinctively bisindole-substituted aminopyrazole could be a useful prototype for the discovery of novel therapeutic agents to tackle AD and other GSK-3β associated complex neurological syndromes.

Fisetin Prevents HT22 Cells From High Glucose-Induced Neurotoxicity via PI3K/Akt/CREB Signaling Pathway.

Hyperglycemia has been widely considered as a key risk factor for diabetic encephalopathy which can cause neuronal apoptosis and cognitive deficits. The flavonoid compound, fisetin, possesses potential neuroprotective effects and also enhances learning and memory. However, the role of fisetin in hyperglycemia-induced neuronal cytotoxicity has not been fully elucidated. In the present study, HT22 murine hippocampal neuronal cell line was used to establish the injured cell model. Cell proliferation and cytotoxicity assay, Hoechst 33258 staining, qRT-PCR, western blot analysis, and specific inhibitor were used to investigate the effect and molecular mechanisms of fisetin on high glucose (HG)-induced neurotoxicity in HT22 cells. Our results showed that 125 μM and 48 h of treatment was identified as optimal damage parameter of HG. Fisetin significantly improved HG-inhibited cell viability. The levels of LDH, malondialdehyde (MDA), and superoxide dismutase (SOD) were noticeably modulated by fisetin, which alleviated HG-induced HT22 cell oxidative damage. Besides, the apoptosis of HT22 cells was rescued by fisetin pretreatment. In addition, fisetin also prevented HG-induced downregulation of the mRNA expression of Bdnf, Gdnf, synaptophysin (Syp), and glutamate ionotropic receptor AMPA type subunit 1 (Gria1) in cells. More importantly, the decreased phosphorylation of phosphoinositide 3 kinase (PI3K), Akt, and cAMP-response element binding protein (CREB) was rescued by fisetin treatment and that neuroprotective effect of fisetin was partially blocked by PI3K inhibitor, LY294002. These findings indicate that fisetin has potent neuroprotective effect and prevents HG-induced neurotoxicity by activation of PI3K/Akt/CREB pathway.

Synthesis and biological evaluation of isoliquiritigenin derivatives as a neuroprotective agent against glutamate mediated neurotoxicity in HT22 cells

Glutamate-induced neurotoxicity is characterized by cellular Ca2+ uptake, which is upstream of reactive oxygen species (ROS)-induced apoptosis signaling and MAPKs activation. In the present study, we synthesized isoliquiritigenin analogs with electron-donating and electron-withdrawing functional groups. These analogs were evaluated for neuroprotective effect against glutamate-induced neurotoxicity in HT22 cells. Among these analogs, compound BS11 was selected as a potent neuroprotective agent. Cellular Ca2+ concentration, ROS level, MAPKs activation and AIF translocation to the nucleus were increased upon treatment with 5 mM glutamate. In contrast, we identified that compound BS11 reduced the cellular Ca2+ concentration and ROS level upon glutamate exposure. Western blot analysis showed that MAPK activation was decreased by treatment with compound BS11. We further identified that cotreatment of compound BS11 and glutamate inhibited translocation of AIF to the nucleus.

Neuroprotective effects of some seaweeds against Zn - induced neuronal damage in HT-22 cells via modulation of redox imbalance, inhibition of apoptosis and acetylcholinesterase activity.

Zinc plays an important role in neuronal signaling and neurotransmission. However, dyshomeostasis of this metal or its accumulation in the brain has been linked with neurological disorders such as Alzheimer's disease and Parkinson's disease. In this study, the neuroprotective effects of Ecklonia maxima (KPM), Gracilaria gracilis (GCL), Ulva lactuca (ULT) and Gelidium pristoides (MNP) in Zn -induced neurotoxicity in HT-22 cells was examined. Cells were treated with Zinc sulphate and/or aqueous - ethanol extracts and cell viability, apoptosis, acetylcholinesterase activity, including some antioxidant enzymes (catalase and superoxide dismutase activity) and glutathione (GSH) levels were determined. Malondialdehyde and nitric oxide levels produced in the Zn and/or seaweed extract treated cells were also determined. Prior treatment with the seaweed extracts improved cell viability and inhibited Zn - induced cell death. Acetylcholinesterase activity was significantly high in Zn treated cells compared to the control. Pre-treatment with the seaweed extracts triggered a decrease in acetylcholinesterase activity in Zn - treated cells. Furthermore, treatment with Zn caused a significant reduction in GSH levels as well as adecrease insuperoxide dismutase and catalase activities. In contrast, the seaweed extract increased antioxidant enzyme activities and GSH levels. An increase in malondialdehyde and nitric oxide levels was also reversed after treatment with the seaweed extracts. These results suggest that the seaweed extracts improved cholinergic transmission disrupted by Zn - induced neurotoxicity and protected the cells against oxidative damage and neuroinflammation. The neuroprotective effects of the seaweed extracts could be linked to their bioactive constituents. Hence these seaweeds are potential sources of active ingredients with neuroprotective potentials and could be used for the development of functional foods and/or nutraceuticals.

Curcumin Alleviates β Amyloid-Induced Neurotoxicity in HT22 Cells via Upregulating SOD2

Curcumin protects neuronal cells exposed to β amyloid (Aβ); the mechanism, however, is still obscure. The aim of this study is to determine whether the type 2 superoxide dismutase (SOD2) mediates curcumin-induced protective effects in Aβ-treated neuronal cells. In this study, the HT22 neuronal cells were exposed to Aβ to imitate neuronal injury in Alzheimer's disease (AD). After 24-h treatment, 10μM Aβ decreased cell viability and mitochondrial functions, including mitochondrial complex activities and mitochondrial membrane potential (MMP), and also downregulated anti-oxidants SOD2, glutathione (GSH), and catalase (CAT) levels (P < 0.05), meanwhile, increased lactic dehydrogenase (LDH) release, apoptosis level, intracellular reactive oxygen species (ROS) and mitochondrial superoxide accumulation (P < 0.05). And, co-administration of 1μM curcumin significantly reduced the Aβ-induced cell injury and oxidative damage above (P < 0.05). Downregulating SOD2 by using small interfering RNA (siRNA), however, significantly abolished the curcumin-induced protective and anti-oxidative effects in HT22 cells (P < 0.05); the scramble (SC)-siRNA did not cause marked effects on the curcumin-induced protective effects (P > 0.05). These findings showed that curcumin can alleviate Aβ-induced injury in neuronal cells, and SOD2 protein may mediate the neuroprotective effects.

Identification of Polygonum orientale constituents using high-performance liquid chromatography high-resolution tandem mass spectrometry.

Our primary focus in this research was to identify and characterize its bioactive compounds for potential therapeutic use. Twenty-seven metabolites of Polygonum orientale were identified using LC-QTOF tandem mass spectrometry. Interestingly, P. orientale extracts included several highly oxygenated flavonoids were isolated from P. orientale by column chromatography. 13C NMR data of highly oxygenated flavonoids (1-7) are reported here for the first time. In addition, nitric oxide, 1,1-diphenyl-2-picrylhydrazyl, and water-soluble tetrazolium salt assays were carried out on the isolated compounds to investigate their anti-inflammatory, anti-oxidant, and neuroprotective activities, respectively. Compounds 1, 2, 3, 5, 7, and 8 significantly attenuated lipopolysaccharide-stimulated NO production in BV2 cells without affecting cell viability. Compounds 9-12 exhibited significant antioxidant activity, while compounds 8, 9, and 12 exhibited protective effects against glutamate-induced neurotoxicity in HT22 cells. Our results indicate that P. orientale is a promising source of natural agents for the potential treatment of inflammation and neurodegenerative diseases.