• Environmental Analysis Health and Toxicology
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• v.19 no.3
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• pp.279-286
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• 2004

Although numerous studies have shown that cadmium disturbs the normal biological processes in central nervous system, the mechanism of toxicity is not well understood. The present study has investigated the effect of cadmium on oxidative stress, Na$^{+}$K$^{+}$ ATPase activity and the aggregation of amyloid beta peptide ($\beta$-amyloid) in neuronal cell line, HT22 cell. LC$_{5}$ and LC$_{50}$ of cadmium for HT22 cell resulted from MTT assay was 4.1 uM and 9.5 uM, respectively. Cadmium (2 to 8 uM) dose-dependently increased the lipid peroxidation and decreased the content of glutathione. Cadmium 4 uM showed a significant decrease in Na$^{+}$/K $^{+}$ ATPase activity as compared with control group. The aggregation of $\beta$-amyloid was accelerated in a dose-dependent manner by the treatment with 2 to 8 uM cadmium. These results suggest that the neurotoxicity of cadmium can be mediated by the increase in oxidative stress and decrease in Na$^{+}$/K$^{+}$ ATPase activity.se activity.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.2
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• pp.499-502
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• 2003

Neurotoxicity of reactive oxygen species(ROS) and neuroprotective effect of Aconiti Radix(AR) against ROS-induced cytotoxicity were determined on cultured mouse cerebral neurons by MTT assay after cerebral neurons were cultured for 5 hours in various concentrations of GO. GO was toxic in a dose-dependent manner on cultured cerebral neurons after cerebral neurons were incubated for 5 hours in media containing 5～40mU/ml GO. While, cultures were pretreated with 180 μg/ml AR for 2 hours increased remarkably cell viability. From these results, it is suggested that GO has toxic effect on cultured mouse cerebral neurons by the decrease of cell viability. And also, herb extract such as AKR is very effective in the protection pf neurotoxicity induced by GO.

• Natural Product Sciences
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• v.15 no.1
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• pp.32-36
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• 2009

Glutamate causes neurotoxicity through formation of reactive oxygen species and activation of mitogen-activated protein kinase (MAPK) pathways. MAPK phosphatase-1 (MKP-1) is one of the phosphatases responsible for dephosphorylation/deactivation of three MAPK families: the extracellular signal-regulated kinase-1/2 (ERK-1/2), the c-Jun N-terminal kinase-1/2 (JNK-1/2), and the p38 MAPK. In this report, the potential involvement of MKP-1 in neuroprotective effects of curcumin, the active ingredient of turmeric (Curcuma longa), was examined using HT22 cells. Glutamate caused cell death and activation of ERK-1/2 but not p38 MAPK or JNK-1/2. Blockage of ERK-1/2 by its inhibitor protected HT22 cells against glutamate-induced toxicity. Curcumin attenuated glutamate-induced cell death and ERK-1/2 activation. Interestingly, curcumin induced MKP-1 activation. In HT22 cells transiently transfected with small interfering RNA against MKP-1, curcumin failed to inhibit glutamate-induced ERK-1/2 activation and to protect HT22 cells from glutamate-induced toxicity. These results suggest that curcumin can attenuate glutamate-induced neurotoxicity by activating MKP-1 which acts as the negative regulator of ERK-1/2. This novel pathway may contribute to and explain at least one of the neuroprotective actions of curcumin.

• Natural Product Sciences
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• v.17 no.3
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• pp.221-224
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• 2011

A $CH_3Cl$ extract from the flower of Lonicera japonica (Lauraceae) significantly protected primary cultures of rat cortical cells injured by the excitotoxic amino acid, L-glutamate. Loganin (1), secoxyloganin (2), caffeic acid (3) rutin (4), hyperoside (5), quercetin-3-O-glucoside (6), lonicerin (7), kaempferol-3-O-rutinoside (8), luteolin-7-O-b-D-glucopyranoside (9), quercetin (10) and luteolin (11) were isolated by bioactivity-guided fractionation from the $CH_3Cl$ fraction and further separated using chromatographic techniques. Caffeic acid, lonicerin, kaempferol-3-O-rutinoside, quercetin and luteolin had significant neuroprotective activities against glutamate-induced neurotoxicity in primary cultures of rat cortical cells at concentrations ranging from $0.1{\mu}M$ to $10.0\;{\mu}M$.

• Archives of Pharmacal Research
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• v.27 no.5
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• pp.495-501
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• 2004

A series of N-substituted-1,3-isoindolinedione derivatives (2-16) were synthesized for the purpose of defining the effect of N-substitution on the anticonvulsant activity of these derivatives. The target compounds (2-16) were obtained by condensation of phthalic anhydride with the corresponding amine derivative. The structures of the synthesized derivatives (2-16) were confirmed by means of IR, $^1$H-NMR, $^{13}$ C-NMR, MS and elemental analyses. The anticonvulsant activity of all compounds (2-16) were evaluated by subcutaneous pentylenetetrazole seizure threshold test at doses of 0.2, 0.4 and 0.8 mmol/kg compared with sodium valproate as a positive control. Their neurotoxicity were determined by the rotorod test. Many of the present series of compounds showed good anticonvulsant activity at the tested doses, as compared to sodium valproate. Three of them (4, 6 and 11) exhibited 100 % protection against convulsions, neurotoxicity and death at all tested doses. Out of the series, two compounds (12 and 13) were completely inactive with 100% mortality. 3-(p-chlorophenyl)-4-(1 ,3-dioxo-2,3-dihydro-1 H-2-isoindolyl) butanoic acid derivative (11) has emerged as the most active compound which is 20 times more active than valproate with ED$_{50}$ 8.7, 169 mg/kg; TD$_{50}$ 413, 406 mg/kg and PI 47.5, 2.4. The results revealed the importance of the combination of baclofenic and phthalimide moieties (compound 11) as a promising anticonvulsant candidate.

• YAKHAK HOEJI
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• v.43 no.4
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• pp.535-540
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• 1999

Glutamate (Glu) receptor-mediated excitoxicity has been implicated in many acute and chronic types of neurological disorders. Exposure of mature rat cortical neurons (15-18 days in culture) to the various concentrations of Glu resulted in a marked neuronal death, whereas immature rat cortical neurons (4∼5 days in culture) were resistant to the Glu-induced toxicity. Glu receptor subtype-specific agonists showed differential extent of toxicity in the immature neurons. The neurons treated with NMDA or kainate (KA) did not exhibit damage. However, quisqualate (QA) treatment induced a considerable cell death (36.1%) in immature enurons. The non-NMDA antagonist DNQX did not reduce this response. Interestingly, the QA-induced toxicity was potentiated by spermine in a concentration-dependent manner. Again, the spermine-enhanced damage was not altered by the polyamine antagonist ifenprodil. Taken together, unlike NMDA or KA, QA can induce neurotoxicity in immature rat cortical neurons and the QA-induced toxicity was potentiated by spermine. The lack of antagonizing effects of DNQX and ifenprodil on QA-induced toxicity and the potentiated toxicity by spermine, respectively, implies that both QA receptor and the polyamine site of NMDA receptor may not mediate the neurotoxicity observed in this study, and that a distinct mechanism(s) may be involved in excitotoxicity in immature neurons.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.1
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• pp.69-74
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• 1999

Both direct and indirect environmental stress to brain were increase the expression of transcription factor c-fos in various populations of neurons. In this study, we examined whether the intraperitoneal injections of lidocaine at doses inducing convulsion within 10 min increased the level of c-fos mRNA and protein in forebrain areas. In situ hybridization using $[^{35}S]UTP-labeled$ antisense c-fos, cRNA increased c-fos mRNA levels though hippocampal formation, piriform cortex, septum, caudate-putamen, neostriatum, and amygdala within 2 hr. In parallel with the mRNA expression, c-FOS protein immunoreactivity was also observed in the same forebrain areas. In contrast to the seizure activity and widespread neuronal degeneration following a kainate treatment, injections of lidocaine did not produce neuronal death within 3 days. The present study indicates that lidocaine induces convulsion and c-fos expression without causing neurotoxicity.

• YAKHAK HOEJI
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• v.56 no.5
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• pp.299-303
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• 2012

Homosyringaldehyde was isolated and identified from the 80% methanol extract of roots of Cynanchum paniculatum. C. paniculatum has been widely used for the treatment of various diseases such as neurasthenia, insomnia, dysmenorrheal and toothache. This compound exerted significant neuroprotective activities against glutamate-induced neurotoxicity in hippocampal HT22 cell line by 37.53% (at the concentration of $100{\mu}M$). We investigated mode of action of this compound. Homosyringaldehyde ($100{\mu}M$) significantly decreased the ROS level and $Ca^{2+}$ concentration in the oxidative stress induced HT22 cells by oxidative glutamate toxicity. Thus, our results suggest that homosyringaldehyde significantly protect HT22 cells against glutamate-induced oxidative stress, via antioxidative activities. As the results, we suggest that homosyringaldehyde may be useful in the treatment of neurogenerative disorders.

• Environmental Analysis Health and Toxicology
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• v.22 no.3
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• pp.279-285
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• 2007

The present study attempted to analyze the mechanism of PCB-induced neurotoxicity with respect to the PKC signaling. Since the developing neuron is particularly sensitive to PCB-induced neurotoxicity, we isolated cerebellar granule cells derived from 7-day old SD rats and grew cells in culture for additional 7 days to mimic PND-14 conditions. Only non-coplanar PCBs at a high dose showed a significant increase of total PKC activity at $[^3H]PDBu$ binding assay, indicating that non-coplanar PCBs are more neuroactive than coplanar PCBs in neuronal cells. PKC isoforms were immunoblotted with respective monoclonal antibodies. PKC-alpha and-epsilon were activated with non-coplanar PCB exposure. The result suggests that coplanar PCBs have a PKC pathway different from non-coplanar PCBs. Activation of PKC with exposure was dampened with treatment of high molecular weight of chitosan. Chilean (M.W. > 1,000 kDa) inhibited the total activity of PKC induced by the non-coplanar PCBs. Translocation of PKC isoforms was also inhibited by the high molecular weight of chitosan. The study demonstrated that non-coplanar PCBs are more potent neurotoxic congeners than coplanar PCBs and the alteration of PKC activities by PCB exposure can be blocked with the treatment of chitosan. The results suggest a potential use of chitosan as a means of nutritional intervention to prevent the harmful effects of pollutant-derived diseases.

• Animal cells and systems
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• v.5 no.2
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• pp.139-143
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• 2001

Alzheimer's disease is the most common form of dementia and no cure is known so far. Extensive genetic works and in vitro experiments combined with clinical observations link amyloid $\beta$--protein (A$\beta$-) to the pathogenesis of Alzheimer's disease (AD). It was hypothesized that $A\beta$- becomes toxic when it adopts a fibrillar conformation. Recently, non-fibrillar form of $A\beta$- was observed and the potential role in the pathogenesis of AD became an interesting subject. In this study, the cytotoxicity of non-fibrillar $A\beta$- and fibrillar $A\beta$- was compared on oxidative stress, membrane damage, or nucleosome break down. Non-fibrillar $A\beta$- was not toxic in peripheral nervous system-derived cells but significantly toxic in central nervous system-derived cells while fibrillar $A\beta$- was non-selectively toxic in both cell culture. The neurotoxicity of non-fibrillar $A\beta$- was reproduced in semi-in vivo culture of mouse brain slice. In conclusion, non-fibrillar $A\beta$- could be more relevant to the selective neurodegeneration in Alzheimer's brains than fibrillar $A\beta$- and further research needs to be done for identification of the cause of AD.