• Journal of Korean Neurosurgical Society
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• v.29 no.7
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• pp.868-876
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• 2000

Objective : Parkinsonian rat models have generally been characterized by unilateral destruction of both the nigrostriatal pathway and the mesolimbic pathway using the neurotoxin 6-hydroxydopamine. The induction of contraversive turning by apomorphine in these models is thought to reflect the stimulation of supersensitive dopamine D2 receptor or receptor-mediated mechanisms in denervated neostriatum. The present study was undertaken to investigate the expression of dopamine D2 receptor in denervated striatum according to modalities of apomorphine(dopamine agonist) treatment after creating a hemiparkinsonian rat model in which there is 6-hydroxydopamine induced destruction of the unilateral dopaminergic nigrostriatal pathway. Methods : After making complete lesion in left side substantia nigra pars compacta(SNpc) by stereotactic injection of 6-hydroxydopamine into medial and lateral areas of SNpc, and confirming successful animal model by apomorphine induced contraversive turning behavior without recovery and complete destruction of ipsilateral SNpc with tyrosine hydroxylase immunostaining in 7th day after operation, 15 rats of parkinsonian model were studied with or without administration of apomorphine at varying doses and durations. According to the modalities of apomorphine treatment for 4 days, these rats were divided into 3 groups, as not-treated group, intermittently treated group and constantly treated group. For investigating the extent of the expression of dopamine D2 receptor in denervated striatum, immunohistochemical staining by dopamine D2 receptor antibody and Western blot were performed. Results : In the D2 receptor antibody immunohistochemical staining, the mean number of positive stained neurons was highest in not-treated group($20.5{\pm}1.14$) of 3 groups. In constantly treated group, the mean number of positive stained neurons was less($3.9{\pm}1.79$) than intermittently treated group(p<0.05). The Western blotting with the D2 receptor antibody revealed that expression of receptors was also highest in not-treated group and less in constantiy treated group than intermittently treated group. Conclusion : Dopamine D2 receptors in denervated striatum of parkinsonian rat models, which were not treated with apomorphine, revealed to be most highly expressed. And, according to doses and durations of apomorphine administration, desensitization of the receptor was more apt to develop with constant treatment than intermittent treatment. In clinical setting, the authors believe that, in long-term treated parkinsonian patients, desensitization of dopamine receptors due to chronic dopaminergic stimulation seems to be partially related to mechanisms of drug tolerance.

• The Korea Journal of Herbology
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• v.28 no.5
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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.

• BMB Reports
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• v.56 no.3
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• pp.202-207
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• 2023

We investigated the neuroprotective effects of deca nano-graphene oxide (daNGO) against reactive oxygen species (ROS) and inflammation in the human neuroblastoma cell line SH-SY5Y and in the 6-hydroxydopamine (6-OHDA) induced Parkinsonian rat model. An MTT assay was performed to measure cell viability in vitro in the presence of 6-OHDA and/or daNGO. The intracellular ROS level was quantified using 2',7'-dichlorofluorescein diacetate. daNGO showed neuroprotective effects against 6-OHDA-induced toxicity and also displayed ROS scavenging properties. We then tested the protective effects of daNGO against 6-OHDA induced toxicity in a rat model. Stepping tests showed that the akinesia symptoms were improved in the daNGO group compared to the control group. Moreover, in an apomorphine-induced rotation test, the number of net contralateral rotations was decreased in the daNGO group compared to the control group. By immunofluorescent staining, the animals in the daNGO group had more tyrosine hydroxylase-positive cells than the controls. By anti-Iba1 staining, 6-OHDA induced microglial activation showed a significantly decrease in the daNGO group, indicating that the neuroprotective effects of graphene resulted from anti-inflammation. In conclusion, nano-graphene oxide has neuroprotective effects against the neurotoxin induced by 6-OHDA on dopaminergic neurons.

• Journal of Korean Neurosurgical Society
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• v.60 no.2
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• pp.138-145
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• 2017

Objective : High frequency stimulation (HFS) of the subthalamic nucleus (STN) is recognized as an effective treatment of advanced Parkinson's disease. However, the neurochemical basis of its effects remains unknown. The aim of this study is to investigate the effects of STN HFS in intact and 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian rat model on changes of principal neurotransmitters, glutamate, and gamma-aminobutyric acid (GABA) in the striatum. Methods : The authors examined extracellular glutamate and GABA change in the striatum on sham group, 6-OHDA group, and 6-OHDA plus deep brain stimulation (DBS) group using microdialysis methods. Results : High-pressure liquid chromatography was used to quantify glutamate and GABA. The results show that HFS-STN induces a significant increase of extracellular glutamate and GABA in the striatum of 6-OHDA plus DBS group compared with sham and 6-OHDA group. Conclusion : Therefore, the clinical results of STN-HFS are not restricted to the direct STN targets but involve widespread adaptive changes within the basal ganglia.

• Journal of Korean Neurosurgical Society
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• v.30 no.6
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• pp.688-698
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• 2001

Objectives : Parkinson's disease is a well-known neurodegenerative disease characterized by dopaminergic cell death in the substantia nigra. The reactive gliosis by activated astrocytes and microglias is no more regarded as a simple sequel of neuronal cell death. Microglial activation takes place in a stereotypic pattern with graded morphologic and functional(resting, activated and phagocytic) changes. In Parkinson's disease animal model, the degree of microglial activation along the nigro-striatal dopaminergic tract has not been studied intensively. The purpose of this study was to elucidate the characteristics of microglial reaction and to grade its degree of activation at substantia nigra and corpus striatum using 6-hydroxydopamine induced rat model of Parkinson's disease. Methods : Using Sprague-Dawley rat, parkinsonian model was made by 6-hydroxydopamine(OHDA) induced destruction of medial and lateral substantia nigra(SN). The rat was sacrificed 3-, 5-, 7-, 14- and 21-day-after operation. For control group, we injected saline with same manner and sacrificed 3-day after operation. With immunohistochemistry, we examined dopaminergic neuronal cells and microglial expression using tyrosine hydroxylase (TH) and OX-42 antibodies, respectively. Also we performed in situ hybridization for osteopontin, a possible marker of subset in activated microglia. Results : 1) In lesioned side of substantia nigra and corpus striatum, the TH immunoreactivity was markedly decreased in whole experimental groups. 2) Using optical densitometry, microglia induced immunoreactivity of OX-42 was counted at SN and corpus striatum. At SN, it was increased significantly on the lesioned side in control and all time-dependent experimental groups. At striatum, it was increased significantly in post lesion 3-day group only(p <0.05). Compared to control group, immunoreactivity of OX-42 on lesioned side was increased in groups, except post lesion 21-day group, at SN. Only post lesion 3-day group showed significance at striatum(p <0.05). Compared to SN region, immunoreactivity of OX-42 was much weaker in striatum. 3) Microscopically, the microglias showed typically different activation pattern. At SN, numerous phagocytic microglias were found at pars compacta and reticularis of lesion side. At striatum, no phagocytic form was found and the intensity of staining was much weaker. 4) At SN, the immunoreactivity of osteopontin showed definite laterality and it was markedly increased at pars compacta of lesion side with relatively short duration time. At striatum, however, it was not detected by in situ hybridization technique. Conclusion : The nigral 6-OHDA induced rat model of Parkinson's disease revealed several characteristic patterns of microglial reaction. At SN, microglias was activated shortly after direct neuronal damage and maintained for about three weeks. In contrast, despite of sufficient dopaminergic insufficiency at striatum, activation of microglias was trivial, and distinguished 3 day later. Antegrade slow neuronal degeneration is major pathophysiology in striatal dopaminergic deficiency. So, the acuteness of neuronal damage and consequential degree of neuronal degeneration may be important factor for microglial activation in neurodegenerative diseases such as Parkinson's disease. Additionally, osteopontin may be a possible marker for several subsets of activated microglia, possibly the phagocytic form.

• The Korea Journal of Herbology
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• v.29 no.3
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• pp.27-33
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• 2014

Objectives : The aim of this study was to investigate the protective effect of extract of Thuja orientalis leaves (TOFE) against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity by inhibition of inflammation in in vitro and in vivo models of Parkinson's disease (PD). Methods : We evaluated the effect of TOFE against lipopolysaccharide (LPS)/1-methyl-4-phenylpyridinium ($MPP^+$) toxicity using nitric oxide (NO) assay, inducible NO synthase and cyclooxygenase 2 western blot, tyrosine hydroxylase and microglia activation immunohistochemistry (IHC) in BV2 cell, primary rat mesencephalic neurons, or C57BL/6 mice. We also evaluated the effect of TOFE in mice PD model induced by MPTP. C57BL/6 mice were treated with TOFE 50 mg/kg for 5 days and were injected intraperitoneally with four administrations of MPTP on the last day. We conducted behavioral tests and IHC analysis to see how TOFE affect MPTP-induced neuronal loss of dopaminergic neurons in substantia nigra pars compacta (SNpc) and striatum (ST) of mice. To assess the anti-inflammation effects, we carried out glial fibrillary acidic protein and macrophage-1 antigen integrin alpha M in IHC in SNpc and ST of mice. Results : In an in vitro system, TOFE decreasesd NO generations in BV2 cells. TOFE protected dopaminergic cells against LPS or $MPP^+$-induced toxicity in primary mesencephalic dopaminergic neurons. In vivo system, TOFE at 50 mg/kg treated group showed improved motor deteriorations than the MPTP only treated group and TOFE significantly protected striatal dopaminergic damage from MPTP-induced neurotoxicity in mice. Moreover, TOFE inhibited activation of astrocyte and microglia in SNpc and ST of the mice. Conclusions : We concluded that TOFE showed anti-parkinsonian effect by protection of dopaminergic neurons against MPTP toxicity through anti-inflammatory actions.