• Journal of Ginseng Research
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• 제25권2호
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• pp.74-81
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• 2001

The effect of Korean Ginseng saponins (total saponin, PD saponin and PT saponin) on the serotonin type 3 receptor, which is known to be involved in nausea and vomiting following anticancer chemotherapy or the general anesthesia, was investigated. after in vitro transcribed recombinant serotonin type 3 receptor in the Xenopus laevis oocyte, classic two electrodes voltage clamp technique was used. All of ginseng saponins inhibited the response of the agonist, serotonin, on the serotonin type 3 receptor in a dose-dependent manner. PT saponin showed to have the inhibitory effect more than 2 times as potent as PD saponin. Total saponin shifted the serotonin dose response plot to the right (EC$\_$50/, 0.70$\pm$0.17 $\mu$M into 3.57$\pm$1.42 $\mu$M, and Hill coefficient, 2.14$\pm$0.60 into 1.52$\pm$1.00). Ginseng saponin did not change the reversal potential (∼0 mV) of serotonin type 3 receptor. These results suggest that Korean ginseng saponin may have the inhibitory effect on serotonin type 3 receptor.

• The Korean Journal of Pain
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• 제18권2호
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• pp.113-117
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• 2005

Background: Serotonin 3 receptor is involved in the modulation of nociceptive transmission in the spinal cord. The serotonin 3 receptor antagonist has been used for the management of opioid-induced nausea and vomiting. The aim of this study was to examine whether the analgesic effect of morphine is antagonized by serotonin 3 receptor antagonists at the spinal level. Methods: Rats were implanted with lumbar intrathecal catheters. For nociception, a formalin solution (5%, $50{\mu}l$) was injected into the hind paw of male Sprague-Dawley rats. To determine whether the effect of intrathecal morphine was mediated via serotonin 3 receptors, serotonin 3 receptor antagonists were intrathecally administered 10 min prior to the morphine delivery. Following the formalin injection, formalin-induced nociceptive behavior (flinching response) was observed for 60 min. Results: Intrathecal morphine produced a dose-dependent suppression of the flinches in both phases during the formalin test. The analgesic action of morphine was not reversed by serotonin 3 receptor antagonists (LY-278,584, ondansetron), which had little per se effect on the formalin-induced nociception. Conclusions: Spinal serotonin 3 receptors may not be involved in the analgesia of morphine on a nociceptive state evoked by a formalin stimulus.

• 약학회지
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• 제35권4호
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• pp.326-331
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• 1991

Brain serotonin and its utilization was investigated on stressed rats after feeding high tryptophan diet for a month. High tryptophan fed rats displayed significantly higher level of serum tryptophan, brain tryptophan, serotonin (5-hydroxytryptamine; 5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) than the control diet fed rats. When rats were treated with 3 hour immobilization (IMMB) stress, serotonin turnover was slightly increased, but not statistically significant, in control diet group rats. However in high tryptophan diet rats, 3 hr IMMB stress resulted in statistically significantly (p<0.05) decreased the serum tryptophan, brain tryptophan and 5-HT level. The concentration of 5-HIAA was significantly increased indicating accelerated utilization of the brain 5-HT of the high trp. fed rat. The utilization pattern of the serotonin was found to be similar among young and adult rats. Rats on a tryptophan enriched diet displayed higher coping ability to the stress as they exhibited smaller increment of corticosterone level. A possble involvement of opioid system was suggested in serotonin utilization by measuring total $^{3}$[H]-naloxone binding in brain.

• 통합자연과학논문집
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• 제9권2호
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• pp.128-135
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• 2016

5-hydroxytryptamine (serotonin) receptor ($5-HT_7R$) 7 is one of G-Protein coupled receptors, which is activated by the neurotransmitter Serotonin. After activation by serotonin, $5-HT_7$ activates the production of the intracellular signaling molecule cyclic AMP. $5-HT_7$ receptor has been found to be involved in the pathophysiology of various disorders. It is reported that $5-HT_7$ receptor antagonists can be used as antidepressant agents. In this study, we report the important structural and chemical parameters for 2-methoxyphenylpiperazinylakanamides as $5-HT_7R$ inhibitors. A 3D QSAR study based on comparative molecular field analysis (CoMFA) was performed. The best predictions were obtained for the best CoMFA model with $q^2$ of 0.594 with 6 components, $r^2$ of 0.986, Fisher value as 60.607, and an estimated standard error of 0.043. The predictive ability of the test set was 0.602. Results obtained the CoMFA models suggest that the data are well fitted and have high predictive ability. The contour maps are generated and studied. The contour analyses may serve as tool in the future for designing of novel and more potent $5-HT_7R$ derivatives.

• The Korean Journal of Physiology and Pharmacology
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• 제23권6호
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• pp.509-517
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• 2019

Escitalopram is one of selective serotonin reuptake inhibitor antidepressants. As an S-enantiomer of citalopram, it shows better therapeutic outcome in depression and anxiety disorder treatment because it has higher selectivity for serotonin reuptake transporter than citalopram. The objective of this study was to determine the direct inhibitory effect of escitalopram on 5-hydroxytryptamine type 3 ($5-HT_3$) receptor currents and study its blocking mechanism to explore additional pharmacological effects of escitalopram through $5-HT_3$ receptors. Using a wholecell voltage clamp method, we recorded currents of $5-HT_3$ receptors when 5-HT was applied alone or co-applied with escitalopram in cultured NCB-20 neuroblastoma cells known to express $5-HT_3$ receptors. 5-HT induced currents were inhibited by escitalopram in a concentration-dependent manner. $EC_{50}$ of 5-HT on $5-HT_3$ receptor currents was increased by escitalopram while the maximal peak amplitude was reduced by escitalopram. The inhibitory effect of escitalopram was voltage independent. Escitalopram worked more effectively when it was co-applied with 5-HT than pre-application of escitalopram. Moreover, escitalopram showed fast association and dissociation to the open state of $5-HT_3$ receptor channel with accelerating receptor desensitization. Although escitalopram accelerated $5-HT_3$ receptor desensitization, it did not change the time course of desensitization recovery. These results suggest that escitalopram can inhibit $5-HT_3$ receptor currents in a non-competitive manner with the mechanism of open channel blocking.

• Biomolecules & Therapeutics
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• 제16권4호
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• pp.299-305
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• 2008

Active cardiovascular anaphylactic response was induced in ovalbumin-sensitized, pithed Sprague-Dawley and Wistar rats. On intravenous administration of the antigen, ovalbumin, marked tachycardia and pressor responses were immediately elicited. Thereafter, a delayed long-lasting severe hypotensive response was observed. These anaphylactic cardiovascular responses were maximal 2-3 weeks after the sensitization, and the response was slightly diminished 6 weeks after sensitization. The immediate pressor response was blocked by a non-selective serotonin antagonist methysergide at a dose-dependent manner, but not by histamine receptor antagonists mepyramine (pyrilamine) or cimetidine. The delayed hypotension was reduced either by histamine $H_1$ receptor antagonist mepyramine or $H_2$ receptor antagonist cimetidine, both in a dose-dependent manner. The tachycardic response was not influenced by serotonin or histamine receptor antagonists examined in this study. Differently from the cardiovascular responses, there was no observable bronchial contraction in Sprague-Dawley rat trachea in contrast to Wistar rat where the trachea contracted to in vitro antigen challenge. The cardiovascular anaphylactic model seems to be useful for studying cardiovascular events that occur exclusively in peripheral heart-blood vessel systems. The involvement of two major anaphylactic mediators, serotonin and histamine, is partially demonstrated.

• The Korean Journal of Physiology
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• 제24권1호
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• pp.67-76
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• 1990

The contractile mechanisms of serotonin were investigated in the renal artery of a rabbit. The helical strips of isolated renal artery were immersed in the normal or $Ca^{2+}$-free tris-buffered Tyrode's solution, which was equilibrated with 100% $O_{2}$ at $35^{\circ}C$. The contraction by serotonin or norepinephrine (NE) began at $1{\times}10^{-7}\;M$ and reached the maximal contraction at $1{\times}10^{-5}\;M$. The maximal contraction by serotonin corresponded to $58.1{\pm}4.2%$ of maximal contraction by NE. Cyproheptadine, a serotonin receptor blocker, shifted the concentration-response curve to the right without any reduction in the maximum response but shifted that of NE to the right with reduction in maximum response. And phentolamine, an ${\alpha}-receptor$ blocker, shifted the concentration-response curve of serotonin or NE without any reduction in maximum responses. The $pA_{2}$ values for cyproheptadine against serotonin and NE were $10.35{\pm}0.04$ and $8.45{\pm}0.13$, respectively. The $pA_{2}$ values for phentolamine against serotonin and NE were $6.87{\pm}0.04$ and $8.14{\pm}0.08$, respectively. after the pretreatment with 6-hydroxydopamine, the contraction induced by 100 mM $K^{+}$, tyramine and serotonin reduced to $83.0{\pm}2.0$, $26.8{\pm}6.2$ and $82.0{\pm}3.5%$ of control, respectively. The contraction by serotonin in the $Ca^{2+}$-free Tyrode's solution was increased and sustained with the addition of $Ca^{2+}$ extracellulary. The serotonin-sensitive intracellular $Ca^{2+}$ pool was depleted completely by the pretreatment with NE, but the NE-sensitive intracellular $Ca^{2+}$ pool was depleted partially by the pretreatment with serotonin. From the above results, it is suggested that the contraction induced by serotonin in the renal artery of a rabbit may be due to mechanisms in which serotonin acts directly on specific serotonin receptors and also acts indirectly on ${\alpha}-adrenoceptors$ by displacing NE from neuronal stores.

• Genomics & Informatics
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• 제5권2호
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• pp.77-82
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• 2007

Serotonin (5-HT), the endogenous nonselective 5-HT receptor agonist, activates the inositol-1,4,5-triphosphate/calcium $(InsP3/Ca^{2+})$ signaling pathway and exerts both stimulatory and inhibitory actions on cAMP production and neuromodulin secretion in rat hypothalamic neurons. Specific mRNA transcripts for 5-HT1A, 5-HT2C and 5-HT4 were identified in rat hypothalamic neurons. These experiments were supported by combined techniques such as cAMP and a $Ca^{2+}$ assays in order to elucidate the associated receptors and signaling pathways. The cAMP production and neuromodulin release were profoundly inhibited during the activation of the Gi-coupled 5-HT1A receptor. Treatment with a selective agonist to activate the Gq-coupled 5-HT2C receptor stimulated InsP3 production and caused $Ca^{2+}$ release from the sarcoplasmic reticulum. Selective activation of the Gs-coupled 5-HT4 receptor also stimulated cAMP production, and caused an increase in neuromodulin secretion. These findings demonstrate the ability of 5-HT receptor subtypes expressed in neurons to induce neuromodulin production. This leads to the activation of single or multiple G-proteins which regulate the $InsP3/Ca^{2+}/PLC-{\gamma}$ and adenyl cyclase / cAMP signaling pathways.

• BMB Reports
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• 제38권2호
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• pp.238-242
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• 2005

5-HT2A is one of major serotonin receptor that is involved in the action of serotonin-targeting drugs. Previous clinical studies have shown an unexpected association between lower cholesterol level and psychiatric diseases, in which T102C polymorphism of HTR2A, gene of 5-HT2A serotonin receptor, might be involved. Therefore, we hypothesized a potential association between lower cholesterol level and T102C polymorphism. The effect of the T102C polymorphism on the serum lipid profiles of 646 subjects without specific psychiatric disease was investigated. Genotype was determined by polymerase chain reaction and restriction fragment length polymorphism analysis. There were significantly lower levels of total cholesterol ($193.6{\pm}35.0$ versus $202.1{\pm}45.5\;mg/dl$, p = 0.016) and HDL-cholesterol ($42.7{\pm}11.6$ versus $46.3{\pm}12.7\;mg/dl$, p = 0.004) in CC genotype than non-CC genotypes. Moreover, multivariate analysis showed that the CC genotype is a strong predictor of a lower HDL-cholesterol level (p < 0.001). In conclusion, this study shows that the CC genotype of the HTR2A gene is related to lower HDL-cholesterol level in Koreans. This is the first demonstration showing the potential genetic relationship between the serotonin receptor gene polymorphism and the HDL-cholesterol level.

• 생물정신의학
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• 제9권1호
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• pp.3-7
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• 2002

Genes involved in the serotonin system are good candidates for the pathogenesis of mood disorder and mood-related disorders, such as eating disorder, obsessive-compulsive disorder, alcoholism, and suicide. Serotonin type 2A(5-HT2A) receptor gene promoter polymorphism(-1438A/G) has been reported. In this article, authors reviewed the literatures regarding association studies between -1438A/G and mood disorder and mood-related disorders. There are controversial results with limited data to date. Further researches on the -1438A/G in psychiatric disorders are required.