• Proceedings of the PSK Conference
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• 2003.10b
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• pp.123.2-123.2
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• 2003

The cellular mechanisms by which excess exposure to the excitatory neurotransmitter glutamate can produce neuronal injury are unknown. In this study, we found that glutamate induced cell death at IC (50) of 100 microM on the cultured human SH-SY5Y neuroblastoma cells. It has been hypothesized that glutamate excitotoxicity is related with the elevation of calcium (Ca) levels. To determine the dependence of glutamate neurotoxicity on Ca environment, extracellular (EDTA) and intracellular (BAPTA/AM) chelator were used. (omitted)

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.217-225
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• 2021

This study aimed to investigate the neuroprotective effects of 1-methoxylespeflorin G11 (MLG), a pterocarpan, against glutamate-induced neurotoxicity in neuronal HT22 hippocampal cells. The protective effects of MLG were evaluated using MTT assay and microscopic analysis. The extent of apoptosis was studied using flow cytometric analysis performed on the damaged cells probed with annexin V/propidium iodide. Moreover, mitochondrial reactive oxygen species (ROS) were assessed using flow cytometry through MitoSOXTM Red staining. To determine mitochondrial membrane potential, staining with tetramethylrhodamine and JC-1 was performed followed by flow cytometry. The results demonstrated that MLG attenuates glutamate-induced apoptosis in HT22 cells by inhibiting intracellular ROS generation and mitochondrial dysfunction. Additionally, MLG prevented glutamate-induced apoptotic pathway in HT22 cells through upregulation of Bcl-2 and downregulation of cleaved PARP-1, AIF, and phosphorylated MAPK cascades. In addition, MLG treatment induced HO-1 expression in HT22 cells. These results suggested that MLG exhibits neuroprotective effects against glutamate-induced neurotoxicity in neuronal HT22 cells by inhibiting oxidative stress and apoptosis.

• The Korea Journal of Herbology
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• v.20 no.2
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• pp.115-125
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• 2005

Objectives : Polygalae Radix (PR) from Polygalae tenuifolia (Polygalaceae) has been clinically used as a sedative, anti-inflammatory, and anti-bacterial agent. To extend pharmacological effects of PR in the central nervous system (CNS) on the basis of its CNS protective effect, the present study was conducted to identify the effect of PR, whether it shows the neuroprotective action against excitatory neurotoxicity. Methods : To identify the protective effect of PR to excitatory neuro-toxic agent, the present study was focused on the PR effect on cell death, that was caused by applying NMDA to nerve cell, elevation of $(Ca^{2+})_i$, releasement of glutamate, and ROS generation. Result : 1. PR methanol extract, at the concentration range of 0.05 to 5 g/ml, significantly inhibited NMDA (1 mM)-induced neuronal cell death as well as MK-801 (non competitive NMDA antagonist). 2. PR methanol extract $(0.5\;{\mu}g/ml)$ inhibited NMDA (1 mM)-induced elevation of cytosolic calcium concentration $[Ca^{2+}]_i$. NMDA application in the presence of MK-801 $(10\;{\mu}M)$ failed to produce the increase of $[Ca^{2+}]_i$ through all the measurement time. 3. PR methanol extract $(0.5\;{\mu}g/ml)$ inhibited the NMDA-induced elevation of glutamate release. Also, MK-801 showed similar protective effects. 4. PR methanol extract $(0.5\;{\mu}g/ml)$ inhibited the NMDA-induced elevation of ROS generation. Also, MK-801 showed similar protective effects. Conclusion : The present study provides the availability of PR to exert its protective effect on the neuronal cell death in various neurodegenerative pathophysiological conditions.

• Natural Product Sciences
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• v.13 no.3
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• pp.268-271
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• 2007

Glutamate-induced oxidative injury contributes to neuronal degeneration in many central nervous system (CNS) diseases, such as epilepsy and ischemia. Bioassay-guided fractionation of the MeOH extract of the seeds of Alpinia katsumadai Hayata (Zingiberaceae) furnished three phenolic compounds, alpinetin (1), pinocembrin (2), and (+)-catechin (3). Compounds 2 and 3 showed the potent neuroprotective effects on glutamate-induced neurotoxicity and reactive oxygen species (ROS) generation in the mouse hippocampal HT22 cells. In addition, Compounds 2 and 3 showed significant DPPH free radical scavenging effect. These results suggest that compounds 2 and 3 could be the effective candidates for the treatment of ROS-related neurological diseases.

• 한국약용작물학회:학술대회논문집
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• 2011.09a
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• pp.308-309
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• 2011

• Proceedings of the PSK Conference
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• 2000.10a
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• pp.222.1-222.1
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• 2000

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.183.1-183.1
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• 2000

• Korean Journal of Acupuncture
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• v.38 no.1
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• pp.32-42
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• 2021

Objectives : In this study, we investigated the neuroprotective effects of ethanol extract of Lonicera japonica flower buds (EELJ) on glutamate-induced neurotoxicity in mouse hippocampus-derived neuronal HT22 cells. Methods : After analyzing the cytoprotective effect of EELJ on glutamate in HT22 cells, the inhibitory effect of apoptosis was studied using flow cytometry. In order to analyze the antioxidant efficacy of EELJ, the levels of reactive oxygen species (ROS) and glutathione (GSH) were investigated, and the effects on the activities of superoxide dismutase (SOD) and catalase (CAT) were also analyzed. Furthermore, the effect of EELJ on the expression of apoptosis regulators such as Bax and Bcl-2 in glutamate-treated HT22 cells was investigated. Results : According the current results, pretreatment with EELJ significantly reduced glutamate-induced loss of cell viability and release of lactate dehydrogenase. EELJ also markedly attenuated glutamate-induced generation of intracellular ROS, which was associated with increased levels of GSH, and activity of SOD and CAT in glutamate-stimulated HT22 cells. In addition, EELJ was strikingly inhibited glutamate-induced apoptosis in HT22 cells. Furthermore, the expression of pro-apoptotic Bax was increased and the expression of anti-apoptotic Bcl-2 was decreased in glutamate-treated HT22 cells, while in the presence of EELJ, their expressions were maintained at the control levels. Conclusions : These findings indicate that EELJ protects glutamate-induced cytotoxicity in HT22 hippocampal neurons through antioxidant activity. Therefore, although identification of biologically active substances of EELJ and re-evaluation through animal experiments is necessary, this natural substance is a promising candidate for further research in preventing and treating oxidative stress-mediated neurodegenerative diseases.

• BMB Reports
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• v.53 no.10
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• pp.527-532
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• 2020

We recently reported that N-adamantyl-4-methylthiazol-2-amine (KHG26693) attenuates glutamate-induced oxidative stress and inflammation in the brain. In this study, we investigated KHG 26693 as a therapeutic agent against glutamate-induced autophagic death of cortical neurons. Treatment with KHG26693 alone did not affect the viability of cultured cortical neurons but was protective against glutamate-induced cytotoxicity in a concentration-dependent manner. KHG26693 attenuated the glutamate-induced increase in protein levels of LC3, beclin-1, and p62. Whereas glutamate decreased the phosphorylation of PI3K, Akt, and mTOR, these levels were restored by treatment with KHG26693. These results suggest that KHG26693 inhibits glutamate-induced autophagy by regulating PI3K/Akt/mTOR signaling. Finally, KHG26693 treatment also attenuated glutamate-induced increases in reactive oxygen species, glutathione, glutathione peroxidase, and superoxide dismutase levels in cortical neurons, indicating that KHG26693 also protects cortical neurons against glutamate-induced autophagy by regulating the reactive oxygen species scavenging system.

• Natural Product Sciences
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• v.21 no.2
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• pp.134-140
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• 2015

The present study aims to investigate the effect of methanol extract of Korean mistletoe (KM; Viscum album var. coloratum), on amyloid $\beta$ protein ($A\beta$) (25-35), a synthetic 25-35 amyloid peptide, -induced neurotoxicity in cultured rat cerebral cortical neurons and memory impairment in mice. Exposure of cultured neurons to $10{\mu}M$ $A\beta$ (25-35) for 24 h induced a neuronal cell death, which was measured by a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay and Hoechst 33342 staining. KM (10, 30 and $50{\mu}g/ml$) significantly inhibited the $A\beta$ (25-35)-induced apoptotic neuronal death. KM ($50{\mu}g/ml$) inhibited 10 μM Aβ (25-35)-induced elevation of intracellular calcium concentration ([Ca²⁺]_i), which was measured by a fluorescent dye, Fluo-4 AM. Glutamate release into medium and generation of reactive oxygen species (ROS) induced by $10{\mu}M$ $A\beta$ (25-35) were also inhibited by KM (10, 30 and $50{\mu}g/ml$). These results suggest that KM may mitigate the $A\beta$ (25-35)-induced neurotoxicity by interfering with the increase of [Ca²⁺]_i and then inhibiting glutamate release and generation of ROS in cultured neurons. In addition, orally administered KM (25 and 50 mg/kg, 7 days) significantly prevented memory impairment induced by intracerebroventricular injection of $A\beta$ (25-35) (8 nmol). Taken together, it is suggested that anti-dementia effect of KM is due to its neuroprotective effect against $A\beta$ (25-35)-induced neurotoxicity and that KM may have therapeutic role in prevention of the progression of Alzheimer's disease.