• Korean Journal of Pharmacognosy
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• v.49 no.3
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• pp.231-239
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• 2018

Parkinson's disease (PD), one of common neurodegenerative diseases, is caused by the death of dopaminergic neurons in the substantia nigra pars compacta. The loss of dopaminergic neurons in PD is associated with oxidative stress and mitochondrial dysfunction. Hyperoside (quercetin 3-O-${\beta}$-D-galactopyranoside) was reported to have protective properties against oxidative stress by reducing intracellular reactive oxygen species (ROS) and increasing antioxidant enzyme activity. In this study, we examined the neuroprotective effect of hyperoside against 1-methyl-4-phenyl pyridinium ($MPP^+$)-induced cell model of PD and the underlying molecular mechanisms. Hyperoside significantly decreased $MPP^+$-induced cell death, accompanied by a reduction in poly ADP-ribose polymerase (PARP) cleavage. Furthermore, it attenuated $MPP^+$-induced intracellular ROS and disruption of mitochondrial membrane potential (MMP), with the reduction of Bax/Bcl-2 ratio. Moreover, hyperoside significantly increased the phosphorylation of Akt, but it has no effects on $GSK3{\beta}$ and MAPKs. Pharmacological inhibitor of PI3K/Akt abolished the cytoprotective effects of hyperoside against $MPP^+$. Taken together, these results demonstrate that hyperoside significantly attenuates $MPP^+$-induced neurotoxicity through PI3K/Akt signaling pathways in SH-SY5Y cells. Our findings suggest that hyperoside might be one of the potential candidates for the treatment of PD.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.3
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• pp.147-151
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• 2009

Repeated psychostimulants induce electroencephalographic (EEG) changes, which reflect adaptation of the neural substrate related to dopaminergic pathways. To study the role of dopamine receptors in EEG changes, we examined the effect of apomorphine, the dopamine D1 receptor antagonist, SCH-23390, and the D2 receptor antagonist, haloperidol, on EEG in rats. For single and repeated apomorphine treatment groups, the rats received saline or apomorphine for 4 days followed by a 3-day withdrawal period and then apomorphine (2.5 mg/kg, i.p.) challenge after pretreatment with saline, SCH-23390, or haloperidol on the day of the experiment. EEGs from the frontal and parietal cortices were recorded. On the frontal cortex, apomorphine decreased the power of all the frequency bands in the single treatment group, and increased the theta (4.5 ${\sim}$ 8 Hz) and alpha (8 ${\sim}$ 13 Hz) powers in the repeated treatment group. Changes in both groups were reversed to the control values by SCH-23390. On the parietal cortex, single apomorphine treatment decreased the power of some frequency bands, which were reversed by haloperidol but not by SCH-23390. Repeated apomorphine treatment did not produce significant changes in the power profile. These results show that adaptation of dopamine pathways by repeated apomorphine treatment could be identified with EEG changes such as increases in theta and alpha power of the frontal cortex, and this adaptation may occur through changes in the D1 receptor and/or the D2 receptor.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.10
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• pp.421-428
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• 2014

Like Alzheimer's disease, Parkinson's Disease(PD) is one of the most common neurodegenerative brain disorders. PD results from the deterioration of dopaminergic neurons in the brain region called the substantia nigra. Currently there is no cure for PD, but diagnosing in its early stage is important to provide treatments for relieving the symptoms and maintaining quality of life. Unlike many diagnosis methods of PD which use a single biomarker, we developed a diagnosis method that uses both biochemical biomarkers and imaging biomarkers. Our method uses ${\alpha}$-synuclein protein levels in the cerebrospinal fluid and diffusion tensor images(DTI). It achieved an accuracy over 91.3% in the 10-fold cross validation, and the best accuracy of 72% in an independent testing, which suggests a possibility for early detection of PD. We also analyzed the characteristics of the brain fiber pathways of Parkinson's disease patients and normal elderly people.

• Journal of Ginseng Research
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• v.42 no.3
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• pp.379-388
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• 2018

Background: Ginsenosides are the main ingredients of Korean Red Ginseng. They have extensively been studied for their beneficial value in neurodegenerative diseases such as Parkinson's disease (PD). However, the multitarget effects of Korean Red Ginseng extract (KRGE) with various components are unclear. Methods: We investigated the multitarget activities of KRGE on neurological dysfunction and neurotoxicity in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. KRGE (37.5 mg/ kg/day, 75 mg/kg/day, or 150 mg/kg/day, per os (p.o.)) was given daily before or after MPTP intoxication. Results: Pretreatment with 150 mg/kg/day KRGE produced the greatest positive effect on motor dysfunction as assessed using rotarod, pole, and nesting tests, and on the survival rate. KRGE displayed a wide therapeutic time window. These effects were related to reductions in the loss of tyrosine hydroxylase-immunoreactive dopaminergic neurons, apoptosis, microglial activation, and activation of inflammatory factors in the substantia nigra pars compacta and/or striatum after MPTP intoxication. In addition, pretreatment with KRGE activated the nuclear factor erythroid 2-related factor 2 pathways and inhibited phosphorylation of the mitogen-activated protein kinases and nuclear factor-kappa B signaling pathways, as well as blocked the alteration of blood-brain barrier integrity. Conclusion: These results suggest that KRGE may effectively reduce MPTP-induced neurotoxicity with a wide therapeutic time window through multitarget effects including antiapoptosis, antiinflammation, antioxidant, and maintenance of blood-brain barrier integrity. KRGE has potential as a multitarget drug or functional food for safe preventive and therapeutic strategies for PD.

• Biomolecules & Therapeutics
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• v.27 no.2
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• pp.178-184
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• 2019

Parkinson's disease is a neurodegenerative disease characterized by the progressive loss of dopaminergic neurons within the substantia nigra pars compacta. In the present study, we investigated whether ${\beta}-Lapachone$ (${\beta}-LAP$), a natural naphthoquinone compound isolated from the lapacho tree (Tabebuia avellanedae), elicits neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. ${\beta}-LAP$ reduced the tyrosine hydroxylase (TH)-immunoreactive fiber loss induced by MPTP in the dorsolateral striatum, and alleviated motor dysfunction as determined by the rotarod test. In addition, ${\beta}-LAP$ protected against MPTP-induced loss of TH positive neurons, and upregulated B-cell lymphoma 2 protein (Bcl-2) expression in the substantia nigra. Based on previous reports on the neuroprotective role of nuclear factor-E2-related factor-2 (Nrf2) in neurodegenerative diseases, we investigated whether ${\beta}-LAP$ induces upregulation of the Nrf2-hemeoxygenae-1 (HO-1) signaling pathway molecules in MPTP-injected mouse brains. Western blot and immunohistochemical analyses indicated that ${\beta}-LAP$ increased HO-1 expression in glial fibrillary acidic protein-positive astrocytes. Moreover, ${\beta}-LAP$ increased the nuclear translocation and DNA binding activity of Nrf2, and the phosphorylation of upstream adenosine monophosphate-activated protein kinase (AMPK). ${\beta}-LAP$ also increased the localization of p-AMPK and Nrf2 in astrocytes. Collectively, our data suggest that ${\beta}-LAP$ exerts neuroprotective effect in MPTP-injected mice by upregulating the p-AMPK/Nrf2/HO-1 signaling pathways in astrocytes.

• The Journal of Korean Physical Therapy
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• v.32 no.6
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• pp.388-390
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• 2020

Objectives: The nigrostriatal tract (NST) connect from the substantia nigra pars compacta to the striatum. A few previous studies have reported on the NST in the Parkinson's disease using a proboblistic tractography method. However, no study has been conducted for identification of the NST using streamline DTT technique. In the current study, we used streamline DTI technique to investigate the reconstruction method and characteristics of the NST in normal subjects. Methods: Eleven healthy subjects were recruited in this study. The NST from the substantia nigra of the midbrain and the striatum of basal ganglia was reconstructed using DTI data. Fractional anisotropy, apparent diffusion coefficient (ADC) values and fiber numbers of the NST were measured. Results: In all subjects, the NST between the substantia nigra of the midbrain and the striatum. Mean values for FA, ADC, and tract volume were 0.460, 0.818, and 154.3 in the right NST, and 0.485, 0.818, and 176.3 in the left NST respectively. Conclusions: we reconstructed the NRT from the substantia nigra of the midbrain and the striatum of the basal ganglia using streamline tractography method. We believe that the findings and the proposed streamline reconstruction method of this study would be useful in future researches on the NST of the human brain.

• BMB Reports
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• v.52 no.4
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• pp.250-258
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• 2019

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by selective and progressive loss of dopaminergic neurons. Genetic and environmental risk factors are associated with this disease. The genetic factors are composed of approximately 20 genes, such as SNCA, parkin, PTEN-induced kinase1 (pink1), leucine-rich repeat kinase 2 (LRRK2), ATP13A2, MAPT, VPS35, and DJ-1, whereas the environmental factors consist of oxidative stress-induced toxins such as 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP), rotenone, and paraquat. The analyses of their functions and mechanisms have provided important insights into the disease process, which has demonstrated that these factors cause oxidative damage and mitochondrial dysfunction. The most invaluable studies have been performed using disease model organisms, such as mice, fruit flies, and worms. Among them, Drosophila melanogaster has emerged as an excellent model organism to study both environmental and genetic factors and provide insights to the pathways relevant for PD pathogenesis, facilitating development of therapeutic strategies. In this review, we have focused on the fly model organism to summarize recent progress, including pathogenesis, neuroprotective compounds, and newer approaches.

• Molecular & Cellular Toxicology
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• v.3 no.4
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• pp.215-221
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• 2007

Neuronal cell toxicity induced by decreased nitric oxide (NO) production may be caused by modulation of constitutive neuronal NO synthase (nNOS). We used lead acetate ($Pb^{2+}$) to modulate physiological NO release and the related pathways of protein kinases like PKC, CaM-KII, and PKA in CATH.a cells, a dopaminergic cell line that has constitutive nNOS activity. In the cells treated with $Pb^{2+}$, cell viability and modulation (phosphorylation) levels of nNOS were determined by MTT assay and Western blot analysis, respectively. nNOS reductase activity (cytochrome c) was also assessed to compare the phosphorylation site-specific nNOS activity. nNOS activity was also determined by NADPH consumption rates. $Pb^{2+}$ treatment alone increased the phosphorylation of nNOS with decreased reductase activity. The phosphorylation levels increased markedly with decreased nNOS reductase activity, when $Pb^{2+}$ was combined with inhibitors for two (PKC and CaM-KII) or three (PKA, PKC and CaM-KII) protein kinases. Interestingly, when the cells were exposed to $Pb^{2+}$ plus PKC or CaM-KII inhibitor, the nNOS was phosphorylated strongly with the lowest activity. However, the levels of phosphorylated nNOS following $Pb^{2+}$ treatment decreased significantly after combined treatment with the PKA inhibitor, and $Pb^{2+}$-induced suppression of reductase activity did not occur. These results demonstrate that physiological NO release in the neuronal cells exposed to $Pb^{2+}$ can be decreased by PKA-mediated nNOS phosphorylation that may be caused by interactions with PKC and/or CaM-KII.

• BMB Reports
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• v.54 no.12
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• pp.592-600
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• 2021

Parkinson's disease (PD) is one of the most common neurodegenerative diseases in the elderly population and is caused by the loss of dopaminergic neurons. PD has been predominantly attributed to mitochondrial dysfunction. The structural alteration of α-synuclein triggers toxic oligomer formation in the neurons, which greatly contributes to PD. In this article, we discuss the role of several familial PD-related proteins, such as α-synuclein, DJ-1, LRRK2, PINK1, and parkin in mitophagy, which entails a selective degradation of mitochondria via autophagy. Defective changes in mitochondrial dynamics and their biochemical and functional interaction induce the formation of toxic α-synuclein-containing protein aggregates in PD. In addition, these gene products play an essential role in ubiquitin proteasome system (UPS)-mediated proteolysis as well as mitophagy. Interestingly, a few deubiquitinating enzymes (DUBs) additionally modulate these two pathways negatively or positively. Based on these findings, we summarize the close relationship between several DUBs and the precise modulation of mitophagy. For example, the USP8, USP10, and USP15, among many DUBs are reported to specifically regulate the K48- or K63-linked de-ubiquitination reactions of several target proteins associated with the mitophagic process, in turn upregulating the mitophagy and protecting neuronal cells from α-synuclein-derived toxicity. In contrast, USP30 inhibits mitophagy by opposing parkin-mediated ubiquitination of target proteins. Furthermore, the association between these changes and PD pathogenesis will be discussed. Taken together, although the functional roles of several PD-related genes have yet to be fully understood, they are substantially associated with mitochondrial quality control as well as UPS. Therefore, a better understanding of their relationship provides valuable therapeutic clues for appropriate management strategies.

• The Korean Journal of Pain
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• v.37 no.1
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• pp.26-33
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• 2024

Background: Sitagliptin is an antidiabetic drug that inhibits dipeptidyl peptidase-4 enzyme. This study aimed to investigate the antinociceptive and anti-inflammatory effects of sitagliptin in formalin and carrageenan tests and determine the possible mechanism(s) of its antinociceptive activity. Methods: Male Swiss mice (25-30 g) and male Wistar rats (180-220 g) were used for formalin and carrageenan tests, respectively. In the formalin test, paw licking time and in the carrageenan test, paw thickness were considered as indexes of pain behavior and inflammation respectively. Three doses of sitagliptin (2.5, 5, and 10 mg/kg) were used in these tests. Also, several antagonists and enzyme inhibitors were used to evaluate the role of adrenergic, serotonergic, dopaminergic, and opioid receptors as well as the NO/cGMP/K_ATP pathway in the antinociceptive effect of sitagliptin (5 mg/kg). Results: Sitagliptin showed significant antinociceptive and anti-inflammatory effects in the formalin and carrageenan tests respectively. In the carrageenan test, all three doses of sitagliptin significantly (P < 0.001) reduced paw thickness. Pretreatment with yohimbine, prazosin, propranolol, naloxone, and cyproheptadine could not reverse the antinociceptive effect of sitagliptin (5 mg/Kg), which indicates that adrenergic, opioid, and serotonin receptors (5HT₂) are not involved in the antinociceptive effects. L-NAME, methylene blue, glibenclamide, ondansetron, and sulpiride were able to reverse this effect. Conclusions: NO/cGMP/K_ATP, 5HT₃ and D₂ pathways play an important role in the antinociceptive effect of sitagliptin. Additionally significant anti-inflammatory effects observed in the carrageenan test might contribute in reduction of pain response in the second phase of the formalin test.