• Journal of Korean Neurosurgical Society
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• v.29 no.11
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• pp.1429-1436
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• 2000

Objectives : This study was performed in cultured rat hippocampal neurons to investigate the acute electrophysiological features of ionotropic glutamate receptors which act as a major excitatory neurotransmitter in mammalian brain. Method : Glutamate receptor agonists were applied into the bath solution embedding in whole-cell patch-clamp recording of single hippocampal neuron. Results : In voltage-clamped at -60mV and the presence of 1mmol $Mg^{2+}$, extracellulary applied NMDA did not induce any inward current. Both the elimination of $Mg^{2+}$ and addition of glycine in bath, however, elicited a NMDAinduced inward current. $Mg^{2+}$ block current was increased gradually in more negative potentials from -30mV, showing a negative slope in I-V plot with $Mg^{2+}$. Glutamate-induced current represented an outward rectification. A non-NMDA receptor component occupied about 40% of glutamate-induced current in the voltage range of -80mV to +60mV. Conclusion : Present study suggests that glutamate activates acutely the non-NMDA receptors which induces an inward current in the level of resting membrane potential. This makes the membrane potential increase and can activate the NMDA receptors that permit calcium influx against $Mg^{2+}$ block. At the depolarized state of neuron, there may be recovery mechanisms of membrane potential to repolarize irrespective of voltage-dependent potassium channels in the hippocampal neurons.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.1
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• pp.265-273
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• 2004

KBPTS is the fortified prescription of Bang-pung-tong-sung-san (BPTS) by adding Spatholobi Clulis and Salviae Miltiorrzae Radix. BPTS prescription has been used in Qriental medicine for the treatments of vascular diseases including hypertension, stroke, and arteriosclerosis, and nervous system diseases. Yet, the overall mechanism underlying its activity at the cellular levels remains unknown. To investigate the protective role of KBPTS on brain functions, noxious stimulations were applied to neurons in vitro and in vivo. KBPTS pretreatment in cultured cortical neurons of albino ICR mice rescued death caused by AMPA, NMDA, and kainate as well as by buthionine sulfoximine (BSO) and ferrous chloride (Fe/sup 2+/) treatments. Furthermore, KBPTS promoted animal's recovery from coma induced by a sublethal dose of KCN and improved survival by a lethal dose of KCN. To examine its physiological effects on the nervous system, we induced ischemia in the Sprague-Dawley rat's brain by middle cerebral artery (MCA) occlusion. Neurological examination showed that KBPTS reduced the time which is required for the animal after MCA occlusion to respond in terms of forelimb and hindlimb movement$. Histological examination revealed that KBPTS reduced ischemic area and edema rate and also protected neurons in the cerebral cortex and hippocampus from ischemic damage. Thus, the present data suggest that KBPTS may play an important role in protecting neuronal cells from external noxious stimulations.

• Molecules and Cells
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• v.22 no.1
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• pp.8-12
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• 2006

Neuron-derived orphan receptor (NOR-1) is a member of the thyroid/steroid receptor superfamily that was originally identified in forebrain neuronal cells undergoing apoptosis. In addition to apoptotic stimuli, activation of several signal transduction pathways including direct neuronal depolarization regulates the expression of NOR-1. In this study we tested whether the expression of NOR-1 is changed following transient ischemic injury in the adult rat brain. NOR-1 mRNA increased rapidly in the dentate gyrus of the hippocampal formation and piriform cortex 3 h after transient global ischemia and returned to basal level at 6 h. On the other hand, oxygen-glucose deprivation of cultured cerebral cortical neurons did not alter the expression of NOR-1. These results suggest that expression of NOR-1 is differentially regulated in different brain regions in response to globally applied brain ischemia, but that hypoxia is not sufficient to induce its expression.

• Archives of Pharmacal Research
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• v.27 no.4
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• pp.454-459
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• 2004

The present study investigated the effects of gossypin, 3,3',4',5,7,8-hexahydroxyflavone 8-glucoside, on the toxicity induced by oxidative stress or $\beta$-amyloid ($A_{\beta}$) in primary cultured rat cortical cells. The antioxidant properties of gossypin were also evaluated by cell-free assays. Gossypin was found to inhibit the oxidative neuronal damage induced by xanthinelxanthine oxidase or by a glutathione depleting agent, D,L-buthionine (S,R)-sulfoximine. In addition, gossypin significantly attenuated the neurotoxicity induced by $A_{{\beta}(25-35)}$. Furthermore, gossypin dramatically inhibited lipid peroxidation initiated by $Fe^{2+}$ and ascorbic acid in rat brain homogenates. It also exhibited potent radical scavenging activity generated from 1 ,1-diphenyl-2-picrylhydrazyl. These results indicate that gossypin exerts neuroprotective effects in the cultured cortical cells by inhibiting oxidative stress- and $A_{\beta}$-induced toxicity, and that the antioxidant properties of gossypin may contribute to its neuroprotective actions.

• Archives of Pharmacal Research
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• v.29 no.8
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• pp.699-706
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• 2006

The present study evaluated antioxidant and neuroprotective activities of hesperidin, a flavanone mainly isolated from citrus fruits, and its aglycone hesperetin using cell-free bioassay system and primary cultured rat cortical cells. Both hesperidin and hesperetin exhibited similar patterns of 1,1-diphenyl-2-picrylhydrazyl radical scavenging activities. While hesperidin was inactive, hesperetin was found to be a potent antioxidant, inhibiting lipid peroxidation initiated in rat brain homogenates by $Fe^{2+}$ and L-ascorbic acid. In consistence with these findings, hesperetin protected primary cultured cortical cells against the oxidative neuronal damage induced by $H_2O_2$ or xanthine and xanthine oxidase. In addition, it was shown to attenuate the excitotoxic neuronal damage induced by excess glutamate in the cortical cultures. When the excitotoxicity was induced by the glutamate receptor subtype-selective ligands, only the N-methyl-D-aspartic acid-induced toxicity was selectively and markedly inhibited by hesperetin. Furthermore, hesperetin protected cultured cells against the $A_{{\beta}(25-35)}-induced$ neuronal damage. Hesperidin, however, exerted minimal or no protective effects on the neuronal damage tested in this study. Taken together, these results demonstrate potent antioxidant and neuroprotective effects of hesperetin, implying its potential role in protecting neurons against various types of insults associated with many neurodegenerative diseases.

• YAKHAK HOEJI
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• v.50 no.2
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• pp.124-128
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• 2006

Astrocyte has emerged as an active regulator of brain function, which connects between blood vessels and neurons as well as is a structural component of the blood-brain barrier, From its structural characteristics, astrocyte seems to sensitively respond to oxygen tension, and, in turn, generate diverse cellular cascades. Therefore, to reveal astrocytlc events by oxygen change, we screened genes whose expressions are upregulated under reoxygenation after hypoxic stress using cDNA representational difference analysis (RDA) technique. Meteorin that regulates glial differentiation was isolated from primary cultured rat astrocytes as a hypoxia/reoxygenation regulatory factor. We cloned rat version of Meteorin (rMe-teorin) and determined full-size sequences of rMeteorin. In addition, RT-PCR analysis revealed that Meteorin was increased under reoxygenation in astrocytes and highly expressed in the developing brain. Collectively, these results suggest that Meteorin may regulate astrocyte-mediated effects in response to the change of oxygen tension in the pathophysiological states.

• Journal of Ginseng Research
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• v.33 no.4
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• pp.294-304
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• 2009

Ginsenosides are among the most well-known traditional herbal medicines frequently used for the treatment of various symptoms in South Korea. The neuroprotective effects of ginsenoside $Rg_3$ (G-$Rg_3$) on cholesterol-oxide-(CO)-induced neurotoxicity were investigated through the analyses of rat brains. The recently accumulated reports show that ginseng saponins (GTS), the major active ingredients of Panax ginseng, have protective effects against neurotoxin insults. In the present study, the neuroprotective effects of G-$Rg_3$ on CO-induced hippocampal excitotoxicity were examined in vivo. The in-vitro studies using rat cultured hippocampal neurons revealed that G-$Rg_3$ treatment significantly inhibited CO-induced hippocampal cell death. G-$Rg_3$ treatment not only significantly reduced CO-induced DNA damage but also attenuated CO-induced apoptosis. The in-vivo studies that were conducted revealed that the intracerebroventricular (i.c.v.) pre-administration of G-$Rg_3$ significantly reduced i.c.v. CO-induced hippocampal damage in rats. To examine the mechanisms underlying the in-vitro and in-vivo neuroprotective effects of G-$Rg_3$ against CO-induced hippocampal excitotoxicity, the effect of G-$Rg_3$ on the CO-induced elevations of the apoptotic cells in cultured hippocampal cells was examined, and it was found that G-$Rg_3$ treatment inhibited CO-induced apoptosis. The histopathological evaluation demonstrated that G-$Rg_3$ significantly diminished the apoptosis in the hippocampus and also spared the hippocampal CA1, CA3, and dentate gyrus neurons. G-$Rg_3$ also significantly improved the CO-caused behavioral impairment. G-$Rg_3$ itself had no effect, however, on the CO-induced inhibition of succinate dehydrogenase activity (data not shown). These results collectively indicate the G-$Rg_3$-induced neuroprotection against CO in rat hippocampus. With regard to the wide use of G-$Rg_3$, this agent is potentially beneficial in treating CO-induced brain injury.

• Animal cells and systems
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• v.1 no.3
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• pp.467-473
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• 1997

Taurine (2-aminoethanesulfonic acid), one of bioactive amino acid in the mammalian brain, is known to exert inhibitory effects on neurons via GABA receptor. In the present study, we examined effects of taurine on glutamateinduced neurotoxicity on hippocampal neuron cell culture using cell counting method and lactate dehydrogenase (LDH) assay. After 10 d of culture, cells were stimulated with appropriate drugs. Only 43% of cultured neuronal cells survived at one day after stimulation with 500 uM L-glutamate for 10 min. Survival rate was enhanced by 82% in the presence of 10 mM taurine. LDH activity from the culture supernatant incubated with a combination of L-glutamate and taurine was less than half of that with L-glutamate alone. In the next series of experiments, interleukin-6 (IL-6) mRNA expression in cultured astrocytes was investigated using reverse tanscription-PCR (RT-PCR). IL-6 mRNA was detected in the astrocytes stimulated with L-glutamate in a dose-dependent manner, while not detected in the unstimulated control astrocytes. The expression of IL-6 mRNA caused by 10 mM glutamate was inhibited by taurine, but not by GABA. These findings demonstrated a neuroprotective action of taurine against glutamate-induced toxicity.

• YAKHAK HOEJI
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• v.46 no.3
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• pp.185-191
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• 2002

Alzheimer's disease (AD) involves neuronal degeneration with impaired cholinergic transmission, particularly in areas of the brain associated with learning and memory. Several cholinesterase inhibitors are widely prescribed to ameliorate the cognitive deficits in AD patients. In an attempt to examine if tacrine and donepezil, two well-known cholinesterase inhibitors, exhibit additional pharmacological actions in primary cultured rat cortical cells, we investigated the effects on neuronal injuries induced by glutamate or N-methyl-D-aspartate (NMDA), $\beta$-amyloid fragment ( $A_{{beta}25-35)}$), and various oxidative insults. Both tacrine and donepezil did not significantly inhibit the excitotoxic neuronal damage induced by glutamate. However, tacrine inhibited the toxicity induced by NMDA in a concentration-dependent fashion. In addition, tacrine significantly inhibited the $A_{{beta}25-35)}$-induced neuronal injury at the concentration of 50 $\mu$M. In contrast, donepezil did not reduce the NMDA- nor $A_{{beta}25-35)}$-induced neuronal injury. Tacrine and donepezil had no effects on oxidative neuronal injuries in cultures nor on lipid peroxidation in vitro. These results suggest that, in addition to its anticholinesterase activity, the neuroprotective effects by tacrine against the NMDA- and $A_{{beta}25-35)$-induced toxicity may be beneficial for the treatment of AD. In contrast, the potent and selective inhibition of central acetylcholinesterase appears to be the major action mechanism of donepezil.

• Journal of Life Science
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• v.27 no.6
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• pp.623-631
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• 2017

In the subventricular zone (SVZ) and the subgranular zone of the brain, neurogenesis occurs throughout one's lifespan. Neural stem cells (NSCs) in these regions divide to maintain their stem cell pools as well as differentiate into neurons and glial cells. To monitor cell division, a thymidine analogue such as 5-ethynyl-2'-deoxyuridine (EdU) has been used. In some cases, EdU was applied to label newly born neurons. Here, we report about the effects of EdU on the proliferation and differentiation of NSCs cultured from mouse SVZ. First, when NSCs were cultured in a proliferation medium containing EdU for 24 hr, they did not generate any neurons under the following differentiation conditions. When EdU was applied to the proliferating NSCs for 1 hr prior to differentiation, neurogenesis was still substantially reduced. Second, EdU decreased cell proliferation of NSCs in dose- and time-dependent manners. Finally, EdU inhibited differentiation into oligodendrocyte lineage, while the number of glial fibrillary acidic protein (GFAP)-positive astrocytes increased. To our knowledge, these findings are the first to show the effects of EdU on the differentiation of SVZ NSCs and suggest that cell division is necessary for differentiation into neurons and oligodendrocytes.