• Journal of Life Science
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• v.32 no.1
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• pp.11-22
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• 2022

N-methyl-D-aspartate (NMDA) receptors have received considerable attention regarding their involvement in glutamate-induced neuronal excitotoxicity. Resveratrol has been shown to exhibit neuroprotective effects against this kind of overactivation, but the underlying cellular mechanisms are not yet clearly understood. In this study, HT-22 neuronal cells were treated with NMDA in Mg²⁺-free buffer and subsequently used as an experimental model of glutamate excitotoxicity to elucidate the mechanisms of resveratrol-induced neuroprotection. We found that NMDA treatment causes a drop in MTT reduction ability, disrupts inside-negative transmembrane potential of mitochondria, depletes cellular ATP levels, and stimulates intracellular ROS production. Double fluorescence imaging studies demonstrated an increased formation of mitochondrial permeability transition (MPT) pores accompanied by apoptotic cell death, while cobalt protoporphyrin and bilirubin showed protective effects against NMDA-induced mitochondrial injury. On the other hand, zinc protoporphyrin IX significantly attenuated the protective effects of resveratrol which was itself shown to enhance heme oxygenase-1 (HO-1) mRNA and protein expression levels. In cells transfected with HO-1 small interfering RNA, resveratrol failed to suppress the NMDA-induced effects on MTT reduction ability and MPT pore formation. The present study suggests that resveratrol may prevent mitochondrial injury in NMDA- treated HT-22 cells and that enhanced expression of HO-1 is involved in the underlying cellular mechanism.

• Archives of Pharmacal Research
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• v.28 no.3
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• pp.335-342
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• 2005

The effects of ginsenosides Rg$_3$(R) , Rg$_3$(S) and Rg$_5$/Rk$_1$ (a mixture of Rg$_5$ and Rk$_1$ 1:1, w/w), which are components isolated from processed Panax ginseng C.A. Meyer (Araliaceae), on memory dysfunction were examined in mice using a passive avoidance test. The ginsenosides Rg3(R), Rg3(S) or Rg$_5$/Rk$_1$, when orally administered for 4 days, significantly ameliorated the memory impairment induced by the single oral administration of ethanol. The memory impairment induced by the intraperitoneal injection of scopolamine was also significantly recovered by ginsenosides Rg3(S) and Rg$_5$/Rk$_1$. Among the three ginsenosides tested in this study, Rg$_5$/Rk$_1$ enhanced the memory function of mice most effectively in both the ethanol­and scopolamine-induced amnesia models. Moreover, the latency period of the Rg$_5$/Rk$_1$­treated mice was 1.2 times longer than that of the control (no amnesia) group in both models, implying that Rg$_5$/Rk$_1$ may also exert beneficial effects in the normal brain. We also evaluated the effects of these ginsenosides on the excitotoxic and oxidative stress-induced neuronal cell damage in primary cultured rat cortical cells. The excitotoxicity induced by glutamate or N­methyl-D-aspartate (NMDA) was dramatically inhibited by the three ginsenosides. Rg$_3$(S) and Rg$_5$/Rk$_1$ exhibited a more potent inhibition of excitotoxicity than did Rg$_3$(R). In contrast, these ginsenosides were all ineffective against the H$_2$O$_2$- or xanthine/xanthine oxidase-induced oxidative neuronal damage. Taken together, these results indicate that ginsenosides Rg$_3$(S) and Rg$_5$/Rk$_1$ significantly reversed the memory dysfunction induced by ethanol or scopolamine, and their neuroprotective actions against excitotoxicity may be attributed to their memory enhancing effects.

• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.6
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• pp.614-620
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• 2014

Kainic acid (KA) is a excitatory agonist causing epileptic seizure and excitotoxicity in the hippocampus. Gastrodia Elata (GE) is known to have anti-convulsant and anti-oxidant effects. This study was investigated a possible role of GE in suppressing epileptic seizure using KA-induced epilepsy mouse model. Eight-week-old male C57BL/6 mice were administrated GE (50 or 500 mg/kg) once a day for 5 days, and then injected KA (30 mg/kg) intraperitoneally. Behavioral changes in mice by KA were evaluated for 90 minutes immediately after the KA administration. Six hours after the KA administration, their brains were harvested and the expressions of glutamate decarboxylase 67 (GAD-67) and K+-Cl- cotransporter 2 (KCC2) in the hippocampus of the mice were measured by immunohistochemistry.GE delayed the onset of epileptic seizure after KA administration, suppressed the severity of the seizure and decreased the number of severe seizures dose dependently. Moreover, GAD-67 and KCC2 expressions in the cornu ammonis (CA) 1 and CA3 of 500 mg/kg GE administrated mice were significantly increased compared to those in KA-treated mice.GAD-67 and KCC2 play an important role in regulating GABAergic system. Our results suggest that GE has anti-convulsant effect against KA-induced epileptic seizure through enhancing GABAergic system.

• Natural Product Sciences
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• v.29 no.1
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• pp.10-16
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• 2023

We previously reported that dried Lysimachia christinae whole plant extract exerted significant neuroprotective activity. In this study, we tried to isolate neuroprotective compounds of L. christinae. We evaluated the neuroprotective activity of the four fractions (hexane, chloroform, ethyl acetate, and n-butanol fractions) of methanol extract. Among them, ethyl acetate and n-butanol fractions showed most potent neuroprotective activity against glutamate excitotoxicity. Nine compounds were isolated from ethyl acetate and n-butanol fractions of L. christinae extract and identified as cynaroside (1), (3,4,5,6-tetrahydroxytetrahydro-2H-pyran-2-yl)methyl-3-hydroxy-2-octyldopentaconta-23,33-dienoate (2), androst-16-ene-3,6-diol (3), 2-hydroxy-24-propoxytetracos-4-enoic acid (4), 2-hydroxy-24-methoxytetracos-4-enoic acid (5), 12-(stearoyloxy)octadec-9-enoic acid (6), β-sitosterol (7), (E)-4-(3,4-dimethoxyphenyl)but-3-en-1-yl palmitate (8) and (1S,2S,3R,4R)-4-(((2S,3R,4R,5R,6S)-2-(((2R,3R,4S,5R,6R)-2-(3,4-dimethoxyphenethoxy)-3,5-dihydroxy-6-(hydroxymethyl) tetrahydro-2H-pyran-4-yl)oxy)-4,5-dihydroxy-6-methyltetrahydro-2H-pyran-3-yl)oxy)cyclohexane-1,2,3-triol (9) by spectroscopic data such as UV, IR, NMR, Mass spectroscopy. Their neuroprotective activity was evaluated by MTT assay. Cynaroside (1) and androst-16-ene-3,6-diol (3) had significant neuroprotective activity against glutamate-injured HT22 cells. The neuroprotective efficacy of cynaroside (1) and androst-16-ene-3,6-diol (3) was related to their anti-oxidative activity.

• YAKHAK HOEJI
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• v.44 no.1
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• pp.29-35
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• 2000

The methanol extracts were prepared from 46 oriental medicines currently used for stroke treatment, and the effects were assessed on the excitotoxic neuronal cell death induced by L-glutamate(Glu) in primary cultured rat cortical neurons. The extracts from Angelicae gigantis Radix, Manitis Squama, Acori graminei Rhizoma, Uncariae Ramulus et Uncus, Alpiniae Fructus, Paeoniae Radix, and Cnidii Rhizoma inhibited the Glu-induced neurotoxicity with the IC$_50$ values of 95.2, 218.6, 263.3, 295.1, 297.9, 310.1, and 446.7 $\mu$g/ m$\ell$, respectively. The extracts from Arisaematis Rhizoma, Loranthi Ramulus, Anemarrhenae Rhizoma, Carthami Flos, Clematidis Radix, Bambusae Concretio Silicea, and Angelicae koreanae Radix also exhibited significant inhibition of the toxicity. In contrast, the extracts from Aconiti Tuber Araliae cordatae Radix, Curcumae Rhizoma, Leonuri Herba, Polygalae Radix, Salviae Radix, and Siegesbeckiae Herba increased the Glu-induced toxicity at the concentrations of 500 and 1000 $\mu$g/m$\ell$. Rest of the extracts evaluated in the present study showed minor or negligible inhibition. liken together the oriental medicines including Angelicae gigantis Radix, Muitis Squama, Acori graminei Rhizoma, Uncariae Ramulus et Uncus, and Alpiniae Fructus appear to exert pharmacological effects through the inhibition of excitotoxic neuronal cell death. Further studies are in progress to characterize active principles in these extracts.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.2
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• pp.85-89
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• 2003

The basic mechanism for the excitation of the peripheral vestibular receptors following acute hypotension induced by sodium nitroprusside (SNP) or hemorrhage was investigated in anesthetized rats. Electrical activity of the afferent vestibular nerve was measured after pretreatment with kynurenic acid, an NMDA receptor antagonist. The activity of the vestibular nerve at rest following acute hypotension induced by SNP or simulating hemorrhage was a greater increase than in control animals. The gain of the vestibular nerve with sinusoidal rotation following acute hypotension increased significantly compared to control animals. The acute hypotension induced by SNP or hemorrhage did not change the activity of the afferent vestibular nerve after kynurenic acid injection. These results suggest that acute hypotension produced excitation of the vestibular hair cells via glutamate excitotoxicity in response to ischemia.

• Korean Journal of Medicinal Crop Science
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• v.12 no.5
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• pp.415-423
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• 2004

Myristica fragrans seed from Myristica fragrans Houtt (Myristicaceae) has various pharmacological activities peripherally and centrally. The present study aims to investigate the effect of the methanol extract of Myristica fragrans seed (MF) on kainic acid (KA)-induced neurotoxicity in primary cultured rat cerebellar granule neuron. MF, over a concentration range of 0.05 to $5\;{\mu}g/ml$ inhibited KA $(500\;{\mu}M)-induced$ neuronal cell death, which was measured by trypan blue exclusion test and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. MF $(0.5\;{mu}g/ml)$ inhibited glutamate release into medium induced by KA $(500\;{\mu}M)$, which was measured by HPLC. Pretreatment of MF $(0.5\;{mu}g/ml)$ inhibited KA $(500\;{\mu}M)-induced$ elevation of cytosolic calcium concentration $([Ca^{2+}]_c)$, which was measured by a fluorescent dye, Fura 2-AM, and generation of reactive oxygen species (ROS). These results suggest that MF prevents KA-induced neuronal cell damage in vitro.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.673-679
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• 1997

It has been generally accepted that glutamate mediates the ischemic brain damage, excitotoxicity, and induces release of neurotransmitters, including norepinephrine(NE), in ischemic milieu. In the present study, the role of nitric oxide(NO) in the ischemia-induced $[^3H]norepinephrine([^3H]NE)$ release from cortex slices of the rat was examined. Ischemia, deprivation of oxygen and glucose from $Mg^{2+}-free$ artificial cerebrospinal fluid, induced significant release of $[^3H]NE$ from cortex slices. This ischemia-induced $[^3H]NE$ release was significantly attenuated by glutamatergic neurotransmission modifiers. $N^G-nitro-L-arginine$ methyl ester(L-NAME), $N^G-monomethyl-L-arginine$ (L-NMMA) or 7-nitroindazole, nitric oxide synthase inhibitors attenuated the ischemia-evoked $[^3H]NE$ release. Hemoglobin, a NO chelator, and 5, 5- dimethyl-L-pyrroline-N-oxide(DMPO), an electron spin trap, inhibited $[^3H]NE$ release dose-dependently. Ischemia-evoked $[^3H]NE$ release was inhibited by methylene blue, a soluble guanylate cyclase inhibitor, and potentiated by 8-bromo-cGMP, a cell permeable cGMP analog, zaprinast, a cGMP phosphodiesterase inhibitor, and S-nitroso-N-acetylpenicillamine (SNAP), a nitric oxide generator. These results suggest that the ischemia-evoked $[^3H]NE$ release is mediated by NMDA receptors, and activation of NO system is involved.

• Natural Product Sciences
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• v.9 no.4
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• pp.249-255
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• 2003

Zizypus is one of the herbs widely used in Korea and China due to CNS calming effect. The present study aims to investigate the effect of the methanol extract of Zizyphi Jujube Semen (ZJS) on kainic acid (KA)-induced neurotoxicity in cultured rat cerebellar granule neuron. ZJS, over a concentration range of 0.05 to $5\;{\mu]g/ml$, inhibited KA $(500\;{\mu}M)-induced$ neuronal cell death, which was measured by a trypan blue exclusion test and a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. Pretreatment of ZJS $(0.5\;{\mu}g/ml)$ inhibited KA$(50\;{\mu}M)$-induced elevation of cytosolic calcium concentration $([Ca^{2+}]_c)$, which was measured by a fluorescent dye, Fura 2-AM, and generation of reactive oxygen species (ROS). ZJS $(0.5\;{\mu}g/ml)$ inhibited glutamate release into medium induced by KA $(500\;{\mu}M)$, which was measured by HPLC. These results suggest that ZJS prevents KA-induced neuronal cell damage in vitro.

• Korean Journal of Medicinal Crop Science
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• v.11 no.4
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• pp.298-305
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• 2003

Polygalae Radix (PR) from Polygala tenuifolia. (Polygalaceae) is traditionally used in China and Korea, since this herb has a sedative, antiinflammatory, and antibacterial agent. To extend pharmacological actions of PR in the CNS on the basis of its CNS inhibitory effect, the present study examined whether PR has the neuroprotective action against kainic acid (KA) -induced cell death in primarily cultured rat cerebellar granule neurons. PR, over a concentration range of 0.05 to $5{\mu}g/ml$ inhibited KA $(500\;{\mu}M)$-induced neuronal cell death, which was measured by a trypan blue exclusion test and a 3-[4,5-dimethylthiazol-2-y1]-2,5-diphenyl-tetrazolium bromide (MTT) assay. PR $(0.5{\mu}g/ml)$ inhibited glutamate release into medium induced by KA $(500\;{\mu}M)$, which was measured by HPLC. Pretreatment of PR $(0.5{\mu}g/ml)$ inhibited KA $(500\;{\mu}M)$-induced elevation of cytosolic calcium concentration $([Ca^{2+}]_c)$ which was measured by a fluorescent dye, Fura 2-AM, and generation of reactive oxygen species (ROS). These results suggest that PR prevents KA-induced neuronal cell damage in vitro.