• Biomolecules & Therapeutics
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• v.30 no.4
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• pp.334-339
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• 2022

Peroxiredoxin 6 (PRDX6) is a bifunctional protein with both glutathione peroxidase and calcium-independent phospholipase activity. Recently, we reported that PRDX6 plays an important role in dopaminergic neurodegeneration in Parkinson's disease. However, the relationship between PRDX6 function and emotional behavior remains elusive. In the present study, we examined depression- and anxiety-like behaviors in PRDX6-overexpressing transgenic (PRDX6-Tg) mice using the forced swim test, tail suspension test, open field paradigm, and elevated plus-maze. PRDX6-Tg mice exhibited depression-like behaviors and low anxiety. In particular, female PRDX6-Tg mice exhibited anxiolytic behavior in the open field test. Furthermore, the serotonin content in the cortex and 5-hydroxytryptophan-induced head twitch response were both reduced in PRDX6-Tg mice. Interestingly, levels of dopa decarboxylase expression in the cortex were decreased in male PRDX6-Tg mice but not in female mice. Our findings provide novel insights into the role of PRDX6 in 5-HT synthesis and suggest that PRDX6 overexpression can induce depression-like behaviors via downregulation of the serotonergic neuronal system.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.102-102
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• 1995

The present study was undertaken to investigate the behavioral and biochemical effects of ginseng total sponin (GTS) on methamphetamine-treated mice. GTS (50 or 100 mg/kg) was administered intraperitoneally two times with 2 hour interval. Two hours after the second injection of GTS, methamphetamine (2 mg/kg) was administered subcutaneously. The ambulatory activity of mice was measured by the ti1ting-type ambulometer every 10 min. for 1 hour. Methamphetamine-induced hyperactivity was reduced by GTS. in a dose-dependent manner. To study the neurochemical mechanism underlying the GTS effects, monoamine contents were measured from brain tissues. After 45 min. of methamphetamine injection. mice were sacrificed and monoamine contents were determined from the striatum. Biochemical analysis revealed that GTS reduced the methamphetamine- induced increase in striatal dopamine contents. These observations indicate that inhibition of methamphetamine-induced hyperactivity by GTS is mediated by the modulation of dopaminergic nervous system, and it could be helpful for the therapy of hyperactivity.

• 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 Pharmacology
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• v.22 no.2
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• pp.79-87
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• 1986

Recently it has been shown that central dopaminergic system regulates the renal function and that intracerebroventricularly (icv) administered dopamine (DA) produces antidiuresis and antinaturiuresis, resembling icv norepinephrine, and evidence has been accumulated which would suggest the involvement of adrenergic system in the DA effects. It was attempted therefore in this study to see whether the DA effect is influenced by pretreatment of yohimbine which is known as a specific ${\alpha}_2-adrenoceptor$ antagonist. Yohimbine produced, when given icv in doses of $100\;{\mu}g/kg$, marked antidiuresis and antinatriuresis along with decreases in renal perfusion and glomerular filtration. DA, in doses of $15\;{\mu}g/kg$, also produced antidiuresis and antinaturiuresis. However, after yohimbine-pretreatment DA $15\;{\mu}g/kg$ improved renal hemodynamics, and electrolyte excretion and urine flow rate transiently increased. With $150\;{\mu}g/kg$ DA, the antidiuresis was more marked in the control group. But the yohimbine-pretreated animals responded with marked diuresis and natriuresis, sodium excretion increasing more than three-fold, which lasted for 20 minutes. $K^+-excretion$, osmolar clearance as well as free-water reabsorption increased. Renal hemodynamics improved partly. Apomorphine, a DA agonist, when given icv in doses of $150\;{\mu}g/kg$, produced diuresis and naturiuresis, concomitant with increased renal hemodynamics. Yohimbine-pretreatment however did not abolish the apomorphine-induced diuresis and naturiuresis. Antidiuresis and antinatriuresis elicited by norepinephrine, $10\;{\mu}g/kg$, was not affected by yohimbine-pretreatment. These results indicate that the renal effects of icv DA is not so simple as those of norepinephrine, and the diuretic natriuretic cffect which had been masked by the hemodynamic effect becomes manifest only when the decreases in hemodynamics were removed by the pretreatment of yohimbine. It was further suggested that those DA receptors which mediate the natriuretic response to icv DA is not affected by yohimbine, whereas those receptors involved in the decrease in renal hemodvnamics are blocked by yohimbine. And the possibility of involvement of adrcnergic system in the DA action is not substantiated.

• Korean Journal of Biological Psychiatry
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• v.4 no.1
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• pp.95-101
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• 1997

The recent hypothesis about the pathophysiology of schizophrenia has been centered mainly on two theories, i.e. dopamine hypothesis and serotonin hypothesis. We investigate the correlations between plasma monoamine metabolite concentrations and clinical symptoms in schizophrenic patients. The first purpose of our study was to examine whether the plasma levels of HVA(homovanillic acid) and 5-HIAA(hydroxyindoleacetic acid) are significantly different in schizophrenics, compared to normal controls. And, with the intention of clarifying the interaction between dopaminergic system and serotoninergic system, the ratio of HVA/5-HIAA also was measured. The second purpose was whether the basal(pre-treatment) levels of these metabolites show the correlation with clinical symptoms. Finally, third purpose was whether basal HVA and 5-HIAA levels can be held as a predictor of treatment response. We used Scale for the Assessment of Positive Symptoms(SAPS) and Scale for the Assessment of Negative Symptoms(SANS) as the clinical symptom rating scales. Our results were as followed, 1) only the level of basal plasma HVA was significantly differ in schizophrenics. 5-HIAA and HVA/5-HIAA were not. 2) basal HVA showed significant correlation with SAPS score, especially delusion subscale. 3) the higher was the basal HVA level, the more improvement in clinical symptoms was observed. The basal 5-HIAA level and the HVA/5-HIAA ratio did not show any significant findings. These results support the dopamine hypothesis of schizophrenia, but fail to examine on the possible involvement of serotonin in schizophrenia.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.99-107
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• 1998

Numerous studies have demonstrated a negative association between cigarette smoking and Parkinson's disease. The present study was undertaken to investigate whether chronic exposure of mice to cigarette smoke a(footed the metabolism of 1-methyl-1113,6-tetrahydro-pyridine (MPTP) by cytochrome P4SO (P-450) or flavin-containing monooxygenase (FMO) in the hepatic microsomes of C57BL6/J mice. Adult male C57BL6/J mice were exposed to mainstream smoke generated from 15 cigarettes for 10 min a day and 5 day per week for 6 weeks. MPTP (10 mg/kg body weight) was administered to mice by subcutaneous injection for 6 consecutive days. Microsolnal P-450 content was increased by MPTP, smoke exposure, or both, but NADPH cytochrome P-450 reductase activity was rather decreased by the same treatments. The activities of benzo(a)pyrene hydroxylase, 7-ethoxycoumarin O-deethylase and ethoxyresorufin O-deethylase were significantly increased by the exposure of cigarette smoke, but were not or little affected by MPTP treatment. Benzphetamine N-demethylase activity was not affected either by MPTP treatment or by cigarette smoke exposure, but it was significantly increased by the combined MPTP treatment with cigarette smoke exposure, showing their synergic effect for the induction of the enzyme activity. Interestingly, in vitro studies of hepatic FMO and P-450 system both O-oxygenation and N-demethylation of MPTP were increased in the smoke-exposed or in the MPTP-treated mice. These results suggest that the enhancement in the N-demethylation as well as O-deethylation of P-450 system and in the N-oxygenation of FMO activity by cigarette smoke exposure in mouse liver may contribute to attenuating the neurotoxic effects of MPTP on the nigrostriatal dopaminergic neurons.

• YAKHAK HOEJI
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• v.60 no.2
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• pp.92-99
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• 2016

Parkinson's disease (PD) is one of the representative neurodegenerative movement disorders with the selective loss of dopaminergic neurons in the substantia nigra. 6-Hydroxydopamine (6-OHDA) is widely used as an experimental model system to mimic PD and has been reported to cause neuronal cell death via oxidative and/or nitrosative stress. Therefore, daily intake of dietary or medicinal plants which fortifies cellular antioxidant capacity can exert neuroprotective effects in PD. In the present study, we have investigated the protective effect of Korean red ginseng (KRG) against 6-OHDA-induced nitrosative death in C6 glioma cells. Treatment of C6 cells with 6-OHDA decreased cell viability and increased expression of inducible nitric oxide synthase, production of nitric oxide as well as peroxynitrite, and formation of nitrotyrosine. 6-OHDA led to apoptotic cell death as determined by decreased Bcl-2/Bax, phosphorylation of JNK, activation of caspase-3, and cleavage of PARP. Conversely, pretreatment of C6 cells with KRG attenuated 6-ODHA-induced cytotoxicity, apoptosis, and nitrosative damages. To further elucidate the molecular mechanism of KRG protection against 6-OHDA-induced nitrosative cell death, we have focused on the cellular self-defense molecules against exogenous noxious stimuli. KRG treatment up-regulated heme oxygenase-1 (HO-1), a key antioxidant enzyme essential for cellular defense against oxidative and/or nitrosative stress via activation of Nrf2. Taken together, these findings suggest KRG may have preventive and/or therapeutic potentials for the management of PD.

• Toxicological Research
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• v.12 no.1
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• pp.69-79
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• 1996

Primary culture of cerebellar neuronal cells derived from 8-day old Long-Evans rats was used. Pure granule cells, astrocytes or mixed cells culture systems were prepared. These cells were differentiated and developed synaptic connections. And the astrocytes were identified by immunostaining with glial fibrillary acidic protein (GFAP). Methamphetamine (MAP), which acts on dopaminergic system and cadmium (Cd), a toxic heavy metal, were applied and biochemical assays and electrophysiological studies were performed. $LC_50$ values estimated by MTT assay of MAP and Cd were 3 mM and 2$\mu M$ respectively. Cells were treated with 1 mM or 2 mM MAP and 1$\mu M$ $CdCl_2$ for 48 hour, and the incubation media were analyzed for the content of released LDH. MAP (2 mM) and Cd significantly increased the LDH release. Cell viability was decreased in both groups and some cytopathological changes like cell swelling or vacuolization were seen. The cerebellar granule cells were used for measuring membrane currents using whole-cell clamp technique. Sodium and potassium currents were not affected by MAP neither Cd, but calcium current was significantly reduced by Cd but not affected by MAP. Therefore, in vitro neurotoxicity test system using neuronaI cells and astrocytes cultures were established and can be used in screening of potential neurotoxic chemicals.

• Biomolecules & Therapeutics
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• v.22 no.6
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• pp.558-562
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• 2014

Tramadol is an opioid analgesic agent that has been the subject of a series of case reports suggesting potential for misuse or abuse. However, it is not a controlled substance and is not generally considered addictive in Korea. In this study, we examined the dependence potential and abuse liability of tramadol as well as its effect on the dopaminergic and serotonergic systems in rodents. In animal behavioral tests, tramadol did not show any positive effects on the experimental animals in climbing, jumping, and head twitch tests. However, in the conditioned place preference and self-administration tests, the experimental animals showed significant positive responses. Taken together, tramadol affected the neurological systems related to abuse liability and has the potential to lead psychological dependence.

• Anxiety and mood
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• v.2 no.1
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• pp.45-49
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• 2006

Puropse : Disturbances of dopaminergic system might be related to the possible mechanism of panic disorder. This study was aimed to examine the association of DRD2 Taq 1 polymorphism and panic disorder. Methods : One hundred and fourteen patients with panic disorder (62 male (54.4%), mean age $40.96{\pm}0.11$ years) and 200 comparison subjects (114 male (57.0%), mean age $35.57{\pm}8.81$ years)were tested for DRD2 TaqI A polymorphism. We excluded panic patients with comorbid alcohol related disorders, bipolar disorders, and any kinds of psychotic disorders because there have been some reports about association of these disease and DRD2 TaqI A polymorphism. Results : There was significant difference in the frequency of the genotype in DRD2 polymorphism between patients and controls (${\chi}^2$=6.09, df=2, p=0.048). The A1+ allele (A1A1 and A1A2) frequency analysis also showed significant association (${\chi}^2$=4.08, df=1, p=0.043). In addition, we observed a more strong and specific association between panic disorder and the A1+ allele of the DRD2 TaqI polymorphism for men (${\chi}^2$=4.71, df=1, p=0.03), but not for women (${\chi}^2$=0.45, df=1, p=0.50). Conclusion : These results in our Korean sample suggest that the DRD2 TaqI A polymorphism may be associated with panic disorder. Furthermore, we found sex-specific association of DRD2 A1 allele with panic disorder.