• The Korean Journal of Physiology and Pharmacology
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• v.9 no.5
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• pp.263-268
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• 2005

Striatum has important roles in motor control, habitual learning and memory. It receives glutamatergic inputs from neocortex and thalamus, and dopaminergic inputs from substantia nigra. We examined effects of dopamine (DA) on the corticostriatal synaptic transmission using in vitro extracellular recording technique in rat brain corticostriatal slices. Synaptic responses were elicited by stimulation of cortical glutamatergic inputs on the corpus callosum and recorded in the dorsal striatum. Corticostriatal population spike (PS) amplitudes were decreased ($39.4{\pm}7.9$%) by the application of $100{\mu}M$ DA. We applied receptor subtype specific agonists and antagonists and characterized the modulation of corticostriatal synaptic transmission by different DA receptor subtypes. $D_2$ receptor agonist (quinpirole), antagonist (sulpiride), and $D_1$ receptor antagonist (SKF 83566), but not $D_1$ receptor agonist (SKF 38393), induced significantly the reduction of striatal PS. Pretreatment neither with SKF 83566 nor sulpiride significantly affected corticostriatal synaptic inhibition by DA. However, the inhibition of DA was completely blocked by pretreatment with mixed solution of both SKF 83566 and sulpiride. These results suggest that DA inhibits corticostriatal synaptic transmission through both $D_1$ and $D_2$ receptors in concert with each other.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.143-149
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• 2007

Scutellaria baicalensis GEORGI(SB) is used in oriental medicine for the treatment of incipient strokes. Although it has been reported that SB is neuroprotective in a hypoxia model, its mechanism is poorly understood. Here, we investigated the effect of SB on the modulation of retinoic acid receptor a (RARa). Rat cerebrocortical cells were grown in neurobasal medium. On DIV12 cells were treated with SB $(20{\mu}g/ml)$ and given a hypoxic shock $(2%\;O_2/5%\;CO_2,\;3hr)$ on DIV14. In situ hybridization using cRNA probe revealed that RARa mRNA punctae are distributed, in addition to nucleus, throughout neuronal dendrites, where SB upregulated its density by 69.8% (p=0.001) and 129.8% (p=0.001) in both normoxia and hypoxia, respectively. At the protein level, SB upregulated RARa in the neuronal soma by 78.8% (p=0.004) and 23.6% (p=0.001) in both normoxia and hypoxia, respectively. These results indicate that SB upregulates RARa in both normoxia and hypoxia, which might contribute to the neuroprotection.

• Journal of Life Science
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• v.17 no.5 s.85
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• pp.706-713
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• 2007

Scutellaria baicalensis GEORGI(SB) is used in oriental medicine for the treatment of incipient strokes. Although it has been reported that SB is neuroprotective in a hypoxia model, its mechanism is poorly understood. Here, we investigated the effect of SB on the modulation of heme oxygenase-1(HO-1), which has important biological roles in regulating mitochondrial heme protein turnover and in protecting against conditions such as hypoxia, neurodegenerative diseases, or sepsis. Rat cerebrocortical day In vitro(DIV)12 cells were grown in neurobasal medium. On DIV12 cells were treated with SB($20{\mu}g/ml$) and given a hypoxic shock ($2%\;O_2/5%\;CO_2,\;3\;hr$) on DIV14. In situ hybridization results revealed that SB upregulated HO-1 mRNA in neuronal dendrites in both normoxia and hypoxia(38.5% and 59.2%, respectively). At the protein level, SB upregulated HO-1 in the neuronal soma in both normoxia and hypoxia(22.4% and 15.7%, respectively). Interestingly, most significant increase was associated with astrocytes, which increased HO-1 protein by 77.5% compared to SB-untreated culture. These results indicate that SB upregulates both neuronal and glial HO-1 expression, which contributes to the neuroprotection efficacy in hypoxia).

• The Journal of Internal Korean Medicine
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• v.25 no.4
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• pp.324-336
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• 2004

Objectives : The purpose of this investigation is to evaluate the effects of Scutellaria baicalensis GEORGI on alteration in gene expression in a hypoxia model using cultured rat cortical cells. Methods : E18 rat cortical cells were grown in a Neurobasal medium containing B27 supplement. On 12 DIV, Scutellaria baicalensis GEORGI(20 ug/ml) was added to the culture media and left for 24 hrs. On 11 DIV, cells were given a hypoxic insult $(2%\;O_2/5%\;CO_2,\;37^{\circ}C,\;3\;hrs)$, returned to normoxia and cultured for another 24 hrs. Total RNA was prepared from Scutellaria baicalensis GEORGI-untreated (control) and -treated cultures and alteration in gene expression was analysed by microarray using rat 5K-TwinChips. Results : For most of the genes altered in expression, the Global M values were between -0.5 to +0.5. Among these, 1143 genes increased in their expression by more than Global M +0.1, while 1161 genes decreased by more than Global M -0.1. Effects on some of the genes whose functions are implicated in neural viability are as follows: 1) The expression of apoptosis-related genes such as Bad (Global M = 0.39), programmed cell death-2(Pdcd2) (Global M = 0.20) increased, while Purinergic receptor P2X(P2rxl) Global M = -0.22), Bc12-like1(Bc1211)(Global M = -0.19) decreased. 2) The expression of 'response to stress-related genes such as antioxidation-related AMP-activated protein kinase subunit gamma 1 gene (Prkag1) (Global M = 0.14), catalase gene (Global M = 0.14) and Heme Oxygenase(Hmoxl) increased. 3) The expression of Fos like antigen 2 (Fos12) expressed in neurons that survive ischemic insult increased (Global M = 0.97). Conclusions : these data suggest that Scutellaria baicalensis GEORGI increases the expression of antiapoptosis- and antioxidation- related genes in a way that can not yet be explained.

• Journal of Life Science
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• v.14 no.2
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• pp.291-295
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• 2004

Rooibos (Aspalathus linearis) (RB) is a leguminous shrub native to the mountainous areas of the northwestern Cape Province in South Africa. RB tea infusions are the fermentation products of its leaves and fine sterns, and known to have a high antioxidative activity due to the presence of flavonoids and phenolic acids. We investigated the effects of RB tea on the alleviation of oxidative stress on cultured rat cortical neurons in a hypoxic model. Measurement of lactate dehydrogenase (LDH) released into culture media revealed that RB increased cell viabilities in both normoxia (6-18%) and hypoxia (2-24%) dose-dependently (10-100 $\mu\textrm{g}$/ml) on 16 days in vitro (3 days after treatment). Visualization of cell morphology by expression of GFP-Hsc70 fusion protein showed that RB (50 $\mu\textrm{g}$/ml) reduced the average vacuolated soma from 55.4$\pm$4.59% (no RB addition) to 40.9$\pm$6.3% (RB addition) on 5 days after hypoxia. Our results proves efficacy of RB in the neuroprotection of hypoxic neurons and extend application for RB into the prevention and/or treatment of neuronal damages.

• Biomolecules & Therapeutics
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• v.18 no.1
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• pp.39-47
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• 2010

Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor involved in neuronal differentiation, plasticity, survival and regeneration. BDNF draws massive attention mainly due to the potential as a therapeutic target in neurological diseases such as depression and Alzheimer's disease. In a primary screening for the natural compounds enhancing BDNF release from cultured rat primary cortical neuron, we found that compounds such as baicalein, tanshinone IIa, cinnamic acid, epiberberine, genistein and wogonin among many others increased BDNF release. All the compounds at $0.1{\mu}M$ of concentration barely showed stimulatory effect on BDNF induction, however, their combination (mixture 1; baicalein, tanshinone IIa and cinnamic acid, mixture 2; epiberberine, genistein and wogonin) showed synergistic increase in BDNF release as well as mRNA and protein expression. The level of BDNF expression was comparable to the maximum BDNF stimulation attainable by a positive control oroxylin A ($20{\mu}M$) without cell toxicity as determined by MTT analysis. Both mixtures synergistically increased the phosphorylation of extracellular signal-regulated kinase (ERK) as well as cAMP response element binding protein (CREB), an immediate and essential regulator of BDNF expression. Similar to these results, mixture of these compounds synergistically inhibited the up-regulation of inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide treatments in rat primary astrocytes. These results suggest that the combinatorial treatment of natural compounds in lower concentration might be a useful strategy to obtain sufficient BDNF stimulation in neurological disease condition such as depression, while minimizing potential side effects and toxicity of higher concentration of a single compound.

• Journal of Life Science
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• v.11 no.4
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• pp.346-353
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• 2001

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) a prototype of the highly toxid halogenated arylhydrocarbons, bioaccumulates in the food chain and induces a complex spectrum of pathological responses. However, its effect on the nerve system is relatively not well studied. In this study we evaluated TCDDs cytotoxicity on the cortical cell and investigated its effect on the expression 2,3-cyclic nucleotide 3-phosphodiesterase(CNPase), a marker for oilgodendrocytes, The survival rates of 4 DIV cortical cells, that are dissociated from E18 rat cortex and maintained in the presence of TCDD, were 88.8, 83.6, 78.5, and 78.6%(5,10, 20 and 50 nM, respectively) where the reduction in 20 and 50mM TCDD were statistically very significant(p<0.01). Imunocytochemistry of cultured cells revealed that the intensities of immunostaining with an anti-CNP1&2 antibody depended on the concentrations of the toxin. Immunoblot analysis also showed differential expression of CNP1 and CNP2 in the presence of TCDD; the CNP1 expression was dose-dependently decreased. Interestingly, the expression of CNP2 in the presence if TDCC; the CNP1 expression was dose-dependently decreased. Interestingly, the expression of CNP2 fluctuated with the TCDD concentration. These results indicated that CNP1 and 2 are differentially regulated by TCDD, implying the functions of oligodendrocytes are modulated by the toxin.

• Biomolecules & Therapeutics
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• v.15 no.4
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• pp.205-211
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• 2007

The fruits and stems of Opuntia ficus-indica var. saboten have been reported to exhibit a variety of pharmacological actions, including antioxidant, analgesic, anti-inflammatory, and anti-ulcer effects. In the present study, we evaluated effects of the butanol fraction (SK OFB901) prepared from the 50% ethanol extract of the stems on various types of neuronal injuries induced by oxidative stress, excitotoxins, and amyloid ${\beta}\;(A_{\beta})$ in primary cultured rat cortical cells. Its antioxidant and radical scavenging activities were also evaluated by cell-free bioassays. We found that SK OFB901 strongly inhibited the oxidative neuronal damage induced by $H_2O_2$ or xanthine/xanthine oxidase. In addition, it exhibited marked inhibition of the excitotoxic neuronal damage induced by glutamate, N-methyl-D-aspartic acid, or kainate. Furthermore, the $A_{\beta(25-35)}$-induced neurotoxicity was also significantly attenuated by SK OFB901. It was found to inhibit lipid peroxidation initiated by $Fe^{2+}$ and L-ascorbic acid in rat brain homogenates and scavenge 1,1-diphenyl-2-picrylhydrazyl free radicals. These results indicate that the butanol fraction prepared from the stems of Opuntia ficus-indica var. saboten exerts potent antioxidant and neuroprotective effects through multiple mechanisms, implying its potential applications for the prevention or management of neurodegenerative disorders associated with oxidative stress, excitotoxicity, and $A{\beta}$.

• Korean Journal of Medicinal Crop Science
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• v.15 no.6
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• pp.444-450
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• 2007

Dried leaves from Cedrela sinensis A. Juss. (CS), have been observed to possess various pharmacological activity and contain various antioxidant constituents. The protective effect of ethanol extract of CS on hydrogen peroxide $(H_2O_2)-induced$ neurotoxicity was examined using primary cultured rat cortical neurons in the present study. Exposure of cultured neurons to 100 ${\mu}M\;H_2O_2$ caused a significant neuronal death as assessed by a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay and Hoechst 33342 staining. The addition of CS, over a concentration range of 10 to $50{\mu}g/m{\ell}$, concentration-dependently prevented the $H_2O_2-induced$ neuronal apoptotic death. CS $(50{\mu}g/m{\ell})$ significantly inhibited $H_2O_2-induced$ elevation of the cytosolic $Ca^{2+}$ concentration $([Ca^{2+}]_c)$, which was measured by a fluorescent dye, Fluo-4 AM. CS (30 and $50{\mu}g/m{\ell})$ inhibited glutamate release and generation of reactive oxygen species (ROS) induced by $100{\mu}M\;H_2O_2$. These results suggest that CS may mitigate the $H_2O_2-induced$ neurotoxiciy by interfering with the increase of $[Ca^{2+}]_c$, and then inhibiting glutamate release and generation of ROS in cultured neurons.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.3
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• pp.311-319
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• 2018

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (${\Delta}{\psi}_m$). Therefore, pharmacological manipulation of ${\Delta}{\psi}_m$ can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ${\Delta}{\psi}_m$ against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity ($100{\mu}M$, 20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate ($100{\mu}M$)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of $Ca^{2+}$ ($5{\mu}M$). Nobiletin-induced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ${\Delta}{\psi}_m$ were completely abolished in $K^+-free$ medium on pure isolated mitochondria. Taken together, results demonstrate that $K^+$ influx into mitochondria is critically involved in partial mitochondrial depolarization-related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial $K^+$ influx is probably mediated, at least in part, by activation of mitochondrial $K^+$ channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.