• The Korean Journal of Physiology and Pharmacology
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• 제14권1호
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• pp.37-43
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• 2010

The serine/threonine kinase Akt has been shown to play a role of multiple cellular signaling pathways and act as a transducer of many functions initiated by growth factor receptors that activate phosphatidylinositol 3-kinase (PI3K). It has been reported that phosphorylated Akt activates eNDS resulting in the production of NO and that NO stimulates soluble guanylate cyclase (sGC), which results in accumulation of cGMP and subsequent activation of the protein kinase G (PKG). It has been also reported that PKG activates PI3K/Akt signaling. Therefore, it is possible that PI3K, Akt, eNOS, sGC, and PKG form a loop to exert enhanced and sustained activation of Akt. However, the existence of this loop in eNOS-expressing cells, such as endothelial cells or astrocytes, has not been reported. Thus, we examined a possibility that Akt phosphorylation might be enhanced via eNOS/sGC/PKG/PI3K pathway in astrocytes in vivo and in vitro. Phosphorylation of Akt was detected in astrocytes after KA treatment and was maintained up to 72 h in mouse hippocampus. 2 weeks after KA treatment, astrocytic Akt phosphorylation was normalized to control. The inhibition of eNOS, sGC, and PKG significantly decreased Akt and eNDS phosphorylation induced by KA in astrocytes. In contrast, the decreased phosphorylation of Akt and eNDS by eNDS inhibition was significantly reversed with PKG activation. The above findings in mouse hippocampus were also observed in primary astrocytes. These data suggest that Akt/eNOS/sGC/PKG/PI3K pathway may constitute a loop, resulting in enhanced and sustained Akt activation in astrocytes.

• Biomolecules & Therapeutics
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• 제8권2호
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• pp.140-146
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• 2000

Recently, we reported that immunostimulation of primary rat cortical astrocyte caused stimulation of glucose deprivation induced apoptotic cell death. To enhance the understanding of the mechanism of the potentiated cell death of clucose-deprived astrocyte by immunostimulation, we investigated the effect of immunostimulation on the glucose deprivation induced cell death of rat C6 glioma cells. Co-treatment of C6 glioma cells with lipopolysaccharide (LPS, $1\;{\mu}\textrm{g}/ml$) and interferon ${\gamma}(IFN{\gamma},\;100U/ml)$ is serum free condition caused marked elevationo f nitric oxide production ($>50\;{\mu}M$). In this condition, glucose deprivation caused significant release of lactate dehdrogenase (LDH) from C6 glioma cells while control cells did not show LDH release. To investigate whether elevated level of nitric oxide is responsible for the enhanced LDH release in glucose-deprived condition, C6 glioma cells were treated with 3-morphorinosydnonimine (SIN-1) and it was observed that SIN-1 caused increase in LDH release from glucose-deprived C6 glioma cells. Treatment of C6 glioma cells with $25\;{\mu}M$ of pyrrolidinedithiocarbamate (PDTC) which inhibit Nuclear factor kB (NF-kB) activation, caused complete inhibition of nitric oxide production. Treatment of C6 glioma cells with NO synthase inhibitors, $N^{G}$-nitro-L-arginine (NNA) or L-$N{\omega}$-nitro-L-arginine methyl ester (L-NAME), caused inhibition of nitric oxide production and also glucose deprivation induced cell death of cytokine-stimulated C6 glioma cells. In addition, diaminohydroxypyrimidine (DAHP, 5 mM) which inhibits the synthesis of tetrahydrobiopterine (BH4), one of essential cofactors for iNOS activity, caused complete inhibition of NO production from immunostimulated C6 glioma cells. The results from the present study suggest that immunostimulation causes potentiation of glucose deprivation induced death of C6 glioma cells which is mediated at least in part by the increased production of nitric oxide. The vulnerability of immunostimulated C6 glioma cells to hypoglycemic insults may implicate that the elevated level of cytokines in various ischemic and neurodegenerative diseases may play a role in their pathogenesis.

• 생명과학회지
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• 제29권11호
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• pp.1258-1266
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• 2019

양격산화탕은 9가지의 약재로 구성된 처방으로 한의학적 뇌졸중 치료에 가장 널리 사용되는 처방 중 하나이며, 주로 사상체질이론의 소양인 뇌졸중 치료에 적용된다. 본 연구는 실험동물을 이용한 뇌졸중에 대한 양격산화탕의 효과에 대한 연구가 전무하여, photothrombosis로 유발된 허혈성 마우스모델을 이용하여 양격산화탕의 효과를 살펴 보았다. 동물행동학적 변화와 더불어 뇌손상에 미치는 영향을 뇌경색 용적에 대한 조직학적 검색 및 신경염증과 신생세포에 대한 면역조직화학적 검색으로 살펴 보았다. 동물행동학적 결과로 보아, 양격산화탕은 뇌허혈에 의해 손상된 운동기능, 즉 wire grip과 rotarod test에 의한 운동조정과 균형 능력 등에 대한 기능적 회복을 보였으며, 이는 조직학적 검색으로 관찰된 뇌경색 용적의 축소를 동반하였다. 면역조직화학적 결과를 보면, 양격산화탕은 tumor necrosis factor-${\alpha}$와 myeloperoxidase 면역반응세포의 수를 현저히 감소시켰다. 이와 반대로 양격산화탕은 glial fibrillary acidic protein와 ionized calcium-binding adapter molecule 1 면역반응세포의 수를 현저히 증가시켰다. 또한 양격산화탕은 Ki67/doublecortin 면역반응세포의 수를 현저히 증가시켰다. 이상의 결과로 보아, 양격산화탕은 항염증, astrocyte와 microglia의 활성화 및 신경세포의 증식을 통해 뇌경색 용적을 감소시키며, 이는 뇌허혈성 운동장애에 대한 완화 효과로 이어 지는 것을 알 수 있다. 따라서 양격산화탕은 뇌손상에 대한 신경기능적 완화효과를 보여 줌으로서 뇌졸중 환자에 대한 유효한 치료제로 사료된다.

• BMB Reports
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• 제43권4호
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• pp.225-232
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• 2010

Parkinson's Disease (PD) is a common neurodegenerative disease characterized by the progressive degeneration of nigrostriatal dopaminergic (DA) neurons. Although the causative factors of PD remain elusive, many studies on PD animal models or humans suggest that glial activation along with neuroinflammatory processes contribute to the initiation or progression of PD. Additionally, several groups have proposed that dysfunction of the blood-brain barrier (BBB) combined with infiltration of peripheral immune cells play important roles in the degeneration of DA neurons. However, these neuroinflammatory events have only been investigated separately, and the issue of whether these phenomena are neuroprotective or neurotoxic remains controversial. We here review the current knowledge regarding the functions of these neuroinflammatory processes in the brain. Finally, we describe therapeutic strategies for the regulation of neuroinflammation with the goal of improving the symptoms of PD.

• The Korean Journal of Physiology and Pharmacology
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• 제20권3호
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• pp.279-286
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• 2016

Caffeic acid phenethyl ester (CAPE), derived from honeybee hives, is a bioactive compound with strong antioxidant activity. This study was designed to test the neuroprotective effect of CAPE in 3-nitropropionic acid (3NP)-induced striatal neurotoxicity, a chemical model of Huntington's disease (HD). Initially, to test CAPE's antioxidant activity, a 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) antioxidant assay was employed, and CAPE showed a strong direct radical-scavenging effect. In addition, CAPE provided protection from 3NP-induced neuronal cell death in cultured striatal neurons. Based on these observations, the in vivo therapeutic potential of CAPE in 3NP-induced HD was tested. For this purpose, male C57BL/6 mice were repeatedly given 3NP to induce HD-like pathogenesis, and 30 mg/kg of CAPE or vehicle (5% dimethyl sulfoxide and 95% peanut oil) was administered daily. CAPE did not cause changes in body weight, but it reduced mortality by 29%. In addition, compared to the vehicle-treated group, robustly reduced striatal damage was observed in the CAPE-treated animals, and the 3NP-induced behavioral deficits on the rotarod test were significantly rescued after the CAPE treatment. Furthermore, immunohistochemical data showed that immunoreactivity to glial fibrillary acidic protein (GFAP) and CD45, markers for astrocyte and microglia activation, respectively, were strikingly reduced. Combined, these data unequivocally indicate that CAPE has a strong antioxidant effect and can be used as a potential therapeutic agent against HD.

• The Korean Journal of Physiology and Pharmacology
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• 제11권2호
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• pp.37-43
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• 2007

Adenosine has been reported to provide cytoprotection in the central nervous systems as well as myocardium by activating cell surface adenosine receptors. However, the exact target and mechanism of its action still remain controversial. The present study was performed to examine whether adenosine has a protective effect against $A{\beta}$-induced injury in neuroglial cells. The astrocyte-derived human neuroglioma cell line, A172 cells, and $A{\beta}_{25{\sim}35}$ were employed to produce an experimental $A{\beta}$-induced glial cell injury model. Adenosine significantly prevented $A{\beta}$-induced apoptotic cell death. Studies using various nucleotide receptor agonists and antagonists suggested that the protection was mediated by $A_1$ receptors. Adenosine attenuated $A{\beta}$-induced impairment in mitochondrial functional integrity as estimated by cellular ATP level and MTT reduction ability. In addition, adenosine prevented $A{\beta}$-induced mitochondrial permeability transition, release of cytochrome c into cytosol and subsequent activation of caspase-9. The protective effect of adenosine disappeared when cells were pretreated with 5-hydroxydecanoate, a selective blocker of the mitochondrial ATP-sensitive $K^+$ channel. In conclusion, therefore we suggest that adenosine exerts protective effect against $A{\beta}$-induced cell death of A172 cells, and that the underlying mechanism of the protection may be attributed to preservation of mitochonarial functional integrity through opening of the mitochondrial ATP-sensitive $K^+$ channels.

• Journal of Microbiology and Biotechnology
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• 제32권9호
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• pp.1168-1177
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• 2022

Parkinson's disease (PD) is the second-most prevalent neurodegenerative disease and is characterized by dopaminergic neuronal death in the midbrain. Recently, the association between alterations in PD pathology and the gut microbiota has been explored. Microbiota-targeted interventions have been suggested as a novel therapeutic approach for PD. Agathobaculum butyriciproducens SR79^T (SR79) is an anaerobic bacterium. Previously, we showed that SR79 treatment induced cognitive improvement and reduced Alzheimer's disease pathologies in a mouse model. In this study, we hypothesized that SR79 treatment may have beneficial effects on PD pathology. To investigate the therapeutic effects of SR79 on PD, 6-hydroxydopamine (6-OHDA)-induced mouse models were used. D-Amphetamine sulfate (d-AMPH)-induced behavioral rotations and dopaminergic cell death were analyzed in unilateral 6-OHDA-lesioned mice. Treatment with SR79 significantly decreased ipsilateral rotations induced by d-AMPH. Moreover, SR79 treatment markedly activated the AKT/GSK3β signaling pathway in the striatum. In addition, SR79 treatment affected the Nrf2/ARE signaling pathway and its downstream target genes in the striatum of 6-OHDA-lesioned mice. Our findings suggest a protective role of SR79 in 6-OHDA-induced toxicity by regulating the AKT/Nrf2/ARE signaling pathway and astrocyte activation. Thus, SR79 may be a potential microbe-based intervention and therapeutic strategy for PD.

• 대한본초학회지
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• 제27권6호
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• pp.83-90
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• 2012

Objectives : Modified Bo-Yang-Hwan-O-Tang (mBHT) is a polyherbal medicine of twelve herbs traditionally used in the treatment of cerebral and cardiac stroke and vascular dementia. The purpose of this study was to evaluate the neuroprotective effect, pyramidal neuronal cell, inflammation and apoptosis of mBHT against global ischemia in rats. Methods : Global ischemia was produced by two-vessel occlusion(2-VO) in SD male rats. mBHT at dose of 500 mg/kg was orally administrated for 2 weeks or 6 weeks after global ischemia. The histopathological changes of ischemic brain were observed by staining of hematoxylin and eosin (H&E) and Nissl and immunohistochemisty with anti-GFAP (glial fibrillary acidic protein) antibody as a astrocyte marker. The expression of inducible nitric oxide synthase (iNOS) and apoptotic proteins such as Bax, Bcl-2 and caspase-3 was determined by western blot. Results : mBHT treatment significantly inhibited the pyramidal neuronal loss in CA1 of hippocampus of global ischemic rats by 2-VO. mBHT also suppressed the activation of astrocytes in the CA1 at 6 weeks after ischemia. In addition, mBHT significantly increased the expression of anti-apoptotic protein, Bcl-2 on iscemic brain, and significantly attenuated the expression of apoptotic proteins, Bax and caspase-3. Conclusions : These results indicate that mBHT inhibits neuronal cell damage induced in global ischemia by 2-VO, suggesting that mBHT may be a potential candidate for the treatment of vascular dementia.

• 대한본초학회지
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• 제28권5호
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• pp.21-28
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• 2013

Objectives : The aim of this study was to investigate the neuroprotective effects and mechanisms of Cyperi Rhizoma extracts (CRE) using in vitro and in vivo models of Parkinson's disease (PD). Methods : We evaluated the neuroprotective effect of CRE against 1-methyl-4-phenylpyridinium (MPP+) toxicity using tyrosine hydroxylase immunohistochemistry (IHC) in primary rat mesencephalic dopaminergic neurons. In addition, the effect of CRE was evaluated in mice PD model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). For evaluations, C57bl/6 mice were orally treated with CRE 50 mg/kg for 5 days and were injected intraperitoneally with MPTP (20 mg/kg) at 2 h intervals on the last day. To identify the CRE affects on MPTP-induced neuronal loss of dopaminergic neurons in substantia nigra pars compacta (SNpc) and striatum of mice, the behavioral tests and IHC analysis were carried out. Also, we conducted nitric oxide (NO) and tumor necrosis factor-alpha (TNF-${\alpha}$) assay in dopaminergic neurons and IHC using glial markers in SNpc of mice to assess the anti-inflammation effects. Results : In primary mesencephalic culture system, CRE protected dopaminergic cells against $10{\mu}M$ MPP+-induced toxicity at 0.2 and $1.0{\mu}g/mL$. In the behavior tests, CRE treated group showed improved motor deteriorations than those in the MPTP only treated group. CRE significantly protected striatal dopaminergic damage from MPTP-induced neurotoxicity in mice. Moreover, CRE inhibited productions of NO and TNF-${\alpha}$ in dopaminergic culture system and activation of astrocyte and microglia in SNpc of the mice. Conclusion : We concluded that CRE shows anti-parkinsonian effect by protecting dopaminergic neurons against MPP+/MPTP toxicities through anti-inflammatory actions.

• Journal of Ginseng Research
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• 제47권3호
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• pp.390-399
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• 2023

Background: Gintonin (GT), a Panax ginseng-derived lysophosphatidic acid receptor (LPAR) ligand, has positive effects in cultured or animal models for Parkinson's disease, Huntington's disease, and so on. However, the potential therapeutic value of GT in treating epilepsy has not yet been reported. Methods: Effects of GT on epileptic seizure (seizure) in kainic acid [KA, 55mg/kg, intraperitoneal (i.p.)]-induced model of mice, excitotoxic (hippocampal) cell death in KA [0.2 ㎍, intracerebroventricular (i.c.v.)]-induced model of mice, and levels of proinflammatory mediators in lipopolysaccharide (LPS)-induced BV2 cells were investigated. Results: An i.p. injection of KA into mice produced typical seizure. However, it was significantly alleviated by oral administration of GT in a dose-dependent manner. An i.c.v. injection of KA produced typical hippocampal cell death, whereas it was significantly ameliorated by administration of GT, which was related to reduced levels of neuroglial (microglia and astrocyte) activation and proinflammatory cytokines/enzymes expression as well as increased level of the Nrf2-antioxidant response via the upregulation of LPAR 1/3 in the hippocampus. However, these positive effects of GT were neutralized by an i.p. injection of Ki16425, an antagonist of LPA1-3. GT also reduced protein expression level of inducible nitric-oxide synthase, a representative proinflammatory enzyme, in LPS-induced BV2 cells. Treatment with conditioned medium clearly reduced cultured HT-22 cell death. Conclusion: Taken together, these results suggest that GT may suppress KA-induced seizures and excitotoxic events in the hippocampus through its anti-inflammatory and antioxidant activities by activating LPA signaling. Thus, GT has a therapeutic potential to treat epilepsy.