• Korean Journal of Biological Psychiatry
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• v.4 no.2
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• pp.162-167
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• 1997

There is no doubt that dopamine plays a critical role in the etiopathogenesis of schizophrenia. However, there appeared some limitations in explaining the complex phenomena of schizophrenia. Recent research data suggest that dysfunction in serotonergic system may be involved. Before the dopamine hypothesis of schizophrenia became established, the interest in serotonin(5-hydroxytryptamine, 5-HT) as an etiological substrate of this illness occurred. Recently the importance and extent of 5-HT's involvement in the pathophysiology and mechanism of action of antipsychotic drug is actively investigated. In recent years, therapeutic success of clozapine and risperidones has increased attention on the interaction between the 5-HT and dopamine systems in schizophrenia. This led to the concept of serotonin-dopamine antagonist for antipsychotics. The authors review the evidence for the role of 5- HT in schizophrenia and serotonin-dopamine interaction.

• Korean Journal of Biological Psychiatry
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• v.23 no.1
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• pp.1-11
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• 2016

Development of various antidepressants such as monoamine oxidase inhibitors, tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin norepinephrine reuptake inhibitors, and noradrenergic and specific serotonergic antidepressant has led to a tremendous progression of pharmaceutical treatment for depression, but still there are some limitations of current antidepressants, such as treatment-resistant depression and delayed onset of antidepressants. The pathogenesis of depression is unclear because depression is a heterogeneous disease state, and the mechanisms of antidepressants remain uncertain as well. Nevertheless, in an attempt to develop novel antidepressants, some trials have been conducted based on the potential biological mechanism discovered in the numerous research results. This review will provide information about the potential novel antidepressants and the current states of clinical studies using them. In particular, some potential novel antidepressants anti-inflammatory agents, antioxidants, anticholinergics, modulators of Hypothalamic Pituitary Adrenal Axis, glutamate, and opioid systems, as well as some neuropeptides such as susbstance P, neuropeptide Y, and galanin will be discussed.

• The Korean Journal of Pain
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• v.34 no.1
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• pp.58-65
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• 2021

Background: Supraspinal delivery of neurotensin (NTS), which may contribute to the effect of a systemically administered agonist, has been reported to be either pronociceptive or antinociceptive. Here, we evaluated the effects of systemically administered NTSR1 agonist in a rat model of neuropathic pain and elucidated the underlying supraspinal mechanism. Methods: Neuropathic pain was induced by L5 and L6 spinal nerve ligation in male Sprague-Dawley rats. The effects of intraperitoneally administered NTSR1 agonist PD 149163 was assessed using von Frey filaments. To examine the role of 5-HT neurotransmission, a serotonin (5-HT) receptor antagonist dihydroergocristine was pretreated intrathecally, and spinal microdialysis studies were performed to measure the change in extracellular level of 5-HT in response to PD 149163 administration. To investigate the supraspinal mechanism, NTSR1 antagonist 48692 was microinjected into the rostral ventromedial medulla (RVM) prior to systemic PD 149163. Additionally, the effect of intrathecal DHE on intra-RVM PD 149163 was assessed. Results: Intraperitoneally administered PD 149163 exhibited a dose-dependent attenuation of mechanical allodynia. This effect was partially reversed by intrathecal pretreatment with dihydroergocristine and was accompanied by an increased extracellular level of 5-HT in the spinal cord. The PD 149163-produced antinociception was also blocked by intra-RVM SB 48692. Direct injection of PD 149163 into the RVM mimicked the maximum effect of the same drug delivered intraperitoneally, which was reversed by intrathecal dihydroergocristine. Conclusions: These observations indicate that systemically administered NTSR1 agonist produces antinociception through the NTSR1 in the RVM, activating descending serotonergic projection to release 5-HT into the spinal dorsal horn.

• Biomolecules & Therapeutics
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• v.26 no.4
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• pp.368-373
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• 2018

Rapid eye movement (REM) sleep has an essential role in the process of learning and memory in the hippocampus. It has been reported that linalool, a major component of Lavandula angustifolia, has antioxidant, anti-inflammatory, and neuroprotective effects, along with other effects. However, the effect of linalool on the cognitive impairment and behavioral alterations that are induced by REM-sleep deprivation has not yet been elucidated. Several studies have reported that REM-sleep deprivation-induced memory deficits provide a well-known model of behavioral alterations. In the present study, we examined whether linalool elicited an anti-stress effect, reversing the behavioral alterations observed following REM-sleep deprivation in mice. Furthermore, we investigated the underlying mechanism of the effect of linalool. Spatial memory and learning memory were assessed through Y maze and passive avoidance tests, respectively, and the forced swimming test was used to evaluate anti-stress activity. The mechanisms through which linalool improves memory loss and behavioral alterations in sleep-deprived mice appeared to be through an increase in the serotonin levels. Linalool significantly ameliorated the spatial and learning memory deficits, and stress activity observed in sleep-deprived animals. Moreover, linalool led to serotonin release, and cortisol level reduction. Our findings suggest that linalool has beneficial effects on the memory loss and behavioral alterations induced by REM-sleep deprivation through the regulation of serotonin levels.

• Biomolecules & Therapeutics
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• v.25 no.4
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• pp.390-395
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• 2017

The present study investigated the sedative effects of Sophora flavescens (SF) and its bioactive compound, matrine through performing locomotor activity test and the electroencephalography (EEG) analysis in the rat. The underlying neural mechanism of their beneficial effects was determined by assessing c-Fos immunoreactivity and serotonin (5-HT) in the brain utilizing immunohistochemical method and enzyme-linked immunosorbent assay. The results showed that SF and matrine administration had an effect on normalization of caffeine-induced hyperactivity and promoting a shift toward non-rapid eye movement (NREM) sleep. c-Fos-immunoreactivity and 5-HT level in the ventrolateral preoptic nucleus (VLPO), a sleep promoting region, were increased in the both SF and matrine-injected groups. In conclusion, SF and its bioactive compound, matrine alleviated caffeine-induced hyperactivity and promoted NREM sleep by activating VLPO neurons and modulating serotonergic transmission. It is suggested that SF might be a useful natural alternatives for hypnotic medicine.

• BMB Reports
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• v.50 no.1
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• pp.31-36
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• 2017

High-dose caffeine uptake is a developmental stressor and causes food-avoidance behavior (aversion phenotype) in C. elegans, but its mode of action is largely unknown. In this study, we investigated the molecular basis of the caffeine-induced aversion behavior in C. elegans. We found that aversion phenotype induced by 30 mM caffeine was mediated by JNK/MAPK pathway, serotonergic and dopaminergic neuroendocrine signals. In this process, the dopaminergic signaling appears to be the major pathway because the reduced aversion behavior in cat-2 mutants and mutants of JNK/MAPK pathway genes was significantly recovered by pretreatment with dopamine. RNAi depletion of hsp-16.2, a cytosolic chaperone, and cyp-35A family reduced the aversion phenotype, which was further reduced in cat-2 mutants, suggesting that dopaminergic signal is indeed dominantly required for the caffeine-induced food aversion. Our findings suggest that aversion behavior is a defense mechanism for worms to survive under the high-dose caffeine conditions.

• Korean Journal of Biological Psychiatry
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• v.3 no.1
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• pp.121-126
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• 1996

Objects : There is considerable interest in the role of serotonin(5-HT) in the pathophysiology of schizophrenia. Cimetidine, $H_2$ antagonist, produces transient increase in serum prolactin(PRL) levels by indirect serotonergic mechanism in man following intravenous administration. Therefore the authors investigated the effects of cimetidine on serum PRL levels of male unmedicated schizophrenics. Method : Baseline serum prolactin level and psychopathology were measured at 9:00 AM. in the two groups(12 positive schizophrenics, 7 negative schizophrenics) and $T_{30}$ levels were measured 30 minutes after intravenous injection of cimetidine (ie, 9:30 AM) Results: 1) Baseline prolactin levels were not different in the three groups. 2) Prolactin levels of 30 minutes after intravenous injection of cimetidine($T_{30}$) compared with baseline prolactin levels were increased all in the three groups. 3) Degrees of interval change from baseline to $T_{30}$ were significantly different between normal control and negative schizophrenics(p<0.05). Conclusion : The prolactin response to cimetidine was significantly blunted in negative male schizophrenics than normal control. These data are consistent with the hypothesis of an abnormality of serotonergic activity, including down-regulation $5-HT_2$ receptors, in male negative schizophrenics.

• The Korean Journal of Pain
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• v.29 no.3
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• pp.164-171
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• 2016

Background: Nefopam has been known as an inhibitor of the reuptake of monoamines, and the noradrenergic and/or serotonergic system has been focused on as a mechanism of its analgesic action. Here we investigated the role of the spinal dopaminergic neurotransmission in the antinociceptive effect of nefopam administered intravenously or intrathecally. Methods: The effects of intravenously and intrathecally administered nefopam were examined using the rat formalin test. Then we performed a microdialysis study to confirm the change of extracellular dopamine concentration in the spinal dorsal horn by nefopam. To determine whether the changes of dopamine level are associated with the nefopam analgesia, its mechanism was investigated pharmacologically via pretreatment with sulpiride, a dopaminergic D2 receptor antagonist. Results: When nefopam was administered intravenously the flinching responses in phase I of the formalin test were decreased, but not those in phase II of the formalin test were decreased. Intrathecally injected nefopam reduced the flinching responses in both phases of the formalin test in a dose dependent manner. Microdialysis study revealed a significant increase of the level of dopamine in the spinal cord by intrathecally administered nefopam (about 3.8 fold the baseline value) but not by that administered intravenously. The analgesic effects of intrathecally injected nefopam were not affected by pretreatment with sulpiride, and neither were those of the intravenous nefopam. Conclusions: Both the intravenously and intrathecally administered nefopam effectively relieved inflammatory pain in rats. Nefopam may act as an inhibitor of dopamine reuptake when delivered into the spinal cord. However, the analgesic mechanism of nefopam may not involve the dopaminergic transmission at the spinal level.

• Korean Journal of Biological Psychiatry
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• v.13 no.3
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• pp.170-177
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• 2006

Objectives : Disturbances of serotonergic system might be related to the possible mechanism of social phobia. This study was to investigate the association of serotonin transporter gene and social phobia. Methods : Sixty nine patients with social phobia(51 male(73.9%), mean age $35.17{\pm}11.89$ years) and seventy four normal controls(54 male(73.0%), mean age $33.46{\pm}9.63$ years) were tested for serotonin transporter gene-linked polymorphic region(5-HTTLPR) polymorphism. Additionally, patients were grouped into 46 generalized(GEN) and 23 nongeneralized(NGEN) subgroups and 5-HTTLPR polymorphism was compared with that of normal controls. The genotypes and allele frequencies of the 5-HTTLPR polymorphism between social phobia and the control group were compared. Genomic DNA was extracted from their blood and 5-HTTLPR polymorphisms were determined by using polymerase chain reaction. Results : Significant association was observed between the S(ss) genotype and social phobia, by functional classification(p=.010). In allele frequency analysis, a significant association was also observed between the short allele and social phobia(p=.030). A significant associations between S genotype and each subgroup were observed(GEN p=.045 ; NGEN p=.033), but there were no differences in allele frequency. And, no differences in genotype and allele distribution between two subgroups were found. Conclusion : The results in our Korean sample suggest that S genotype of 5-HTTLPR may be associated with social phobia and s allele may be an important genetic factor that activates social phobic symptoms. But, further studies including large number of samples are necessary to elucidate these present findings.

• Journal of Oriental Neuropsychiatry
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• v.22 no.2
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• pp.129-146
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• 2011

Objectives : The purpose of this study was to characterize the putative antidepressant and antianxiolytic effects of the 70% ethanol extract of Polygala japonica(EEPJ) using animal's behavioral experiment in mice. Methods : The effect of EEPJ on the anxioty and depressive disorder was investigated via mice's behavioral experiment like Elevated plus-maze, Horizontal wire test, Open field test, Forced swimming test, Tail suspension test, and it was happen via any mechanism by WAY 100635, a 5-HT1A receptor antagonist and by Flumazenil, a GABAA antagonist Results : 1. In the EPM, single treatments of the EEPJ(200 and 400mg/kg) had usefully antianxiolytic effects versus vehicle, which was medicated via the serotonergic nervous system. 2. In the HWT, single treatments of the EEPJ were no changes in the myorelaxant effects versus vehicle. 3. In the OFT, single treatments of the EEPJ were no changes in the locomotor activity versus vehicle. 4. In the FST, single treatments of the EEPJ(50mg/kg) significantly reduced the immobility time versus vehicle. 5. In the TST, single treatments of the EEPJ(50mg/kg) significantly reduced the immobility time versus vehicle. Conclusions : These results indicate that EEPJ is an effective antidepressant and antianxiolytic activity in mice, and it might be usefully applied for prevention and treatment of depressive disorder through evolutive study like development of various experimental models.