• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.874-880
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• 2010

A series of 13- and 14-membered cyclic enkephalin analogs based on the moderately $\mu$ selective prototype compound Tyr-C[D-$A_2bu$-Gly-Phe-Leu] 8a were synthesized to investigate the structure-activity relationship. The modifications of sequence were mainly focused on two positions 3 and 5, critical for the selective recognition for $\mu$ and $\delta$ opioid receptors. The substitution of hydrophobic $Leu^5$ with hydrophilic $Asp^5$ derivatives led to Tyr-C[D-$A_2bu$-Gly-Phe-Asp(N-Me)] 7 and Tyr-C[D-Glu-Phe-gPhe-rAsp(O-Me)] 5, the peptides with a large affinity losses at both $\mu$ and $\delta$ receptors. The substitution of $Phe^3$ with $Gly^3$ led to Tyr-C[D-Glu-Gly-gPhe-rLeu] 3 and Tyr-C[D-Glu-Gly-gPhe-D-rLeu] 4, the peptides with large affinity losses at $\mu$ receptors, indicating the critical role of phenyl ring of $Phe^3$ for $\mu$ receptor affinities. One atom reduction of the ring size from 14-membered analogs Tyr-C[D-Glu-Phe-gPhe-(L and D)-rLeu] 6a, 6b to 13-membered analogs Tyr-C[D-Asp-Phe-gPhe-(L and D)-rLeu] 1, 2 reduced the affinity at both $\mu$ and $\delta$ receptors, but increased the potency in the nociceptive assay, indicating the ring constrain is attributed to high nociceptive potency of the analogs. For the influence of D- or L-chirality of $Leu^5$ on the receptor selectivity, regardless of chirality and ring size, all cyclic diastereomers displayed marked $\mu$ selectivity with low potencies at the $\delta$ receptor. The retro-inverso analogs display similar or more active at $\mu$ receptor, but less active at $\delta$ receptor than the parent analogs.

• Korean Journal of Biological Psychiatry
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• v.5 no.2
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• pp.215-218
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• 1998

The $5-HT_{2A}$ receptor is of great interest for research into schizophrenia and psychopharmacology in light of the observation that schizophrenic patients has 5-HT cortical-subcortical imbalance and atypical antipsychotic clozpine has $5-HT_{2A}$ antagonists properties. An significant association between schizophrenia and the T102C polymorphism of the gene for $5-HT_{2A}$receptor has been reported. In this study, we investigated an association between schizophrenia and the T102C polymorphism of the gene for $5-HT_{2A}$ receptor in Korean schizophrenic patients. The subjects consisted of 139 schizophrenic patients and 88 normal controls. Genomic DNA was amplified by PCR and digested with MsPI. The uncutt product identified allele 1(nucleotide sequence TCT) ; digested products of 216bp and 156bp identified allele 2(nucleotide sequence TCC). The allele frequencies and the genotypic distribution of $5-HT_{2A}$ receptor gene were not significantly different between schizophrenic patients and normal controls. Since allele frequencies of the T102C polymorphism may differ between individuals of different ethnic backgrounds, it needs to be conducted in an advanced research.

• Korean Journal of Biological Psychiatry
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• v.11 no.1
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• pp.54-60
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• 2004

Objectives:Tardive dyskinesia(TD) is a serious side effect associated with long-term antipsychotic treatments. Some candidate genetic polymorphisms were reported to be associated with TD and possible involvement of serotonergic receptors in the pathophysiology of TD has been suggested. In the present study, we investigated the association between $5-HT_6$ receptor gene polymorphism and TD with schizophrenia. Methods:To investigate the relationship between $5-HT_6$ receptor gene polymorphism and TD, 60 patients with TD were compared with 60 patients without TD. The 267C/T allele of $5-HT_6$ receptor gene was genotyped by means of polymerase chain reaction method. TD was evaluated using the Abnormal Involuntary Movement Scale(AIMS). Results:The patients with the three 267C/T genotype showed no significant differences in age, gender, and duration of illness. No significant difference in genotype frequencies was observed between schizophrenic patients with and without TD. In addition, there was no difference in allele frequencies. Further analysis with an measure of AIMS scores showed that these scores were not significantly influenced by the $5-HT_6$ receptor gene polymorphism. Conclusion:These results suggest that 267C/T polymorphism of $5-HT_6$ receptor gene is not significantly associated with susceptibility to TD in schizophrenia.

• Korean Journal of Biological Psychiatry
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• v.10 no.2
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• pp.133-140
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• 2003

Objective:Some candidate gene polymorphisms were reported to be associated with tardive dyskinesia (TD). The aim of this study was to investigate the association of the 5-$HT_{2A}$ receptor gene polymorphisms with TD in Korean schizophrenic subjects. Method:Subjects were of 59 schizophrenic patients with TD and 60 schizophrenic patients without TD for studying of 5-$HT_{2A}$ receptor gene polymorphisms. TD was evaluated using the Abnormal Involuntary Movement Scale(AIMS). Genomic DNA was amplified by PCR and digestion with MspI and BsmI. Result:There were no statistically significant differences in the demographic variables, such as age, male to female percentage, duration of illnesses and duration of antipsychotic drug exposure between the TD group and control group. 1) T102C polymorphisms and TD Comparing the TD group and control group, the 102T/C allele was associated with a significantly increased risk for TD (${\chi}^2$=5.560, df=1, p=0.018). 2) Three AIMS categories of TD and T102C genotype. There were statistically significant differences in the three AIMS categories(${\chi}^2$=6.835, df=2, p=0.033). Conclusion:These result suggest 102T/C genotypes of the 5-$HT_{2A}$ receptor gene are related to the development of TD. The 102T/C genotypes were associated with significantly higher AIMS orofacial dyskinesia scores. These findings suggest that the 5-$HT_{2A}$ receptor gene is significantly associated with susceptibility to TD in patients with chronic schizophrenia.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2008-2014
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• 2011

Serotonin or 5-hydroxytryptamine subtype 2C ($5-HT_{2C}$) receptor belongs to class A amine subfamily of G-protein-coupled receptor (GPCR) super family and its ligands has therapeutic promise as anti-depressant and -obesity agents. So far, bovine rhodopsin from class A opsin subfamily was the mostly used X-ray crystal template to model this receptor. Here, we explained homology model using beta 2 adrenergic receptor (${\beta}$2AR), the model was energetically minimized and validated by flexible ligand docking with known agonists and antagonists. In the active site Asp134, Ser138 of transmembrane 3 (TM3), Arg195 of extracellular loop 2 (ECL2) and Tyr358 of TM7 were found as important residues to interact with agonists. In addition to these, V208 of ECL2 and N351 of TM7 was found to interact with antagonists. Several conserved residues including Trp324, Phe327 and Phe328 were also found to contribute hydrophobic interaction. The predicted ligand binding mode is in good agreement with published mutagenesis and homology model data. This new template derived homology model can be useful for further virtual screening based lead identification.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1228-1230
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• 2011

A new amine receptor 2 utilizing anthracene and nitrophenyl group as signaling group was designed and synthesized. The receptor 2 only utilizes four amine N-H's and 9-anthracenyl hydrogen to bind anions. The receptor 2 can bind anions through hydrogen bonds with a selectivity of $CH_3CO_2^-$ > $H_2PO_4^-$ > $F^-$ > $C_6H_5CO_2^-$ > $Cl^-$ in highly polar solvent such as DMSO without protonation of amine.

• The Journal of Korean Medicine
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• v.26 no.3 s.63
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• pp.239-248
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• 2005

Objectives : Electroacupuncture (EA)-induced analgesia has been known to be mediated through the activation of opioid, noradrenergic and serotonergic receptors. However, little study on serotonergic mechanism has been performed in an animal model of chronic pain. The present study was designed to elucidate the type of serotonergic receptors responsible for EA analgesia in the chronic pain model. Methods : In rats with complete Freund's: adjuvant-induced inflammation and spinal nerve injury, spinal wide dynamic range (WDR) cell responses to graded electrical stimulation of afferent C fiber were recorded before and after spinal application of selective 5-hydroxytryptamine (5-HT) receptor antagonists. EA stimulation (2Hz, 0.5msec, 3mA) was applied to the contralateral Zusanli point for 30 min. Results : In both models of chronic pain, WDR cell responses were greatly inhibited after EA stimulation. EA-induced inhibition of WDR celt responses was significantly attenuated by spinal application of non-selective 5-HT receptor antagonist, dihydroergocristine Of 5-HT receptor antagonists tested, 5-HT1A (WAY 100635) and 5-HT2 (LY53857) receptor antagonists strongly reduced an ability of EA stimulation to inhibit WDR cell responses. However, 5-HT1B (GR55562) and 5-HT3 (LY278584) receptor antagonists also had weak but significant blocking action on EA-induced inhibitory effect on chronic pain. Conclusions : Dorsal hem cell responses, afferent C fiber stimulation, chronic pain, electroacupuncture, serotonergic receptors.

• Biomolecules & Therapeutics
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• v.14 no.2
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• pp.119-124
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• 2006

This study was performed to investigate the influence of the spinal adenosine $A_1$ receptors on the central regulation of blood pressure (BP) and heart rate (HR), and to define whether its mechanism is mediated by cyclic AMP (cAMP), cyclic GMP (cGMP) or potassium channel. Intrathecal (i.t.) administration of drugs at the thoracic level were performed in anesthetized, artificially ventilated male Sprague-Dawley rats. I.t. injection of adenosine $A_1$ receptor agonist, $N^6$-cyclohexyladenosine (CHA; 1, 5 and 10 nmol) produced dose dependent decrease of BP and HR and it was attenuated by pretreatment of 50 nmol of 8-cyclopentyl-1,3-dimethylxanthine, a specific adenosine $A_1$ receptor antagonist. Pretreatment with a cAMP analogue, 8-bromo-cAMP, also attenuated the depressor and bradycardiac effects of CHA (10 nmol), but not with cGMP analogue, 8-bromo-cGMP. Pretreatment with a ATP-sensitive potassium channel blocker, glipizide (20 nmol) also attenuated the depressor and bradycardiac effects of CHA (10 nmol). These results suggest that adenosine $A_1$ receptor in the spinal cord plays an inhibitory role in the central cardiovascular regulation and that this depressor and bradycardiac actions are mediated by cAMP and potassium channel.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.1
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• pp.31-39
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• 1998

As it has been reported that the depolarization induced acetylcholine (ACh) release is modulated by activation of presynaptic $A_1$ adenosine heteroreceptor and various lines of evidence suggest the $A_2$ adenosine receptor is present in the hippocampus. The present study was undertaken to delineate the role of adenosine receptors on the hippocampal ACh release. Slices from the rat hippocampus were equilibrated with $[^3H]choline$ and then the release amount of the labelled product, $[^3H]ACh$, which was evoked by electrical stimulation (rectangular pulses, 3 Hz, 2 ms, 24 mA, $5\;V/cm^{-1}$, 2 min), was measured, and the influence of various adenosine receptor-related agents on the evoked tritium outflow was investigated. And also, the drug-receptor binding assay was performed in order to confirm the presence of $A_1$ and $A_2$ adenosine receptors in the rat hippocampus. N-ethylcarboxamidoadenosine (NECA), a potent adenosine receptor agonist with nearly equal affinity at $A_1$ and $A_2$ adenosine receptors, in concentrations ranging from $1{\sim}30\;{\mu}M$, decreased the electrically-evoked $[^3H]ACh$ release in a concentration-dependent manner without affecting the basal rate of release. And the effect of NECA was significantly inhibited by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 2 ${\mu}M$), a selective $A_1$ adenosine receptor antagonist, but was not influenced by 3,7-dimethyl-1-propargylxanthine (DMPX, 5 ${\mu}M$), a specific $A_2$ adenosine receptor antagonist. $N^6-cyclopentyladenosine$ (CPA), a selective $A_1$ adenosine receptor agonist, in doses ranging from 0.1 to 10 ${\mu}M$, reduced evoked $[^3H]ACh$ release in a dose-dependent manner without the change of the basal release. And the effect of CPA was significantly inhibited by 2 ${\mu}M$ DPCPX treatment. 2-P-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680C), a potent $A_2$ adenosine receptor agonist, in concentrations ranging from 0.1 to 10 ${\mu}M$, did not alter the evoked ACh release. In the drug-receptor binding assay, the binding of $[^3H]2-chloro-N^6-cyclopentyladenosine$ ($[^3H]$CCPA) to the $A_1$ adenosine receptor of rat hippocampal membranes was inhibited by CPA ($K_i$ = 1.22 nM), NECA ($K_i=10.17 nM$) and DPCPX ($K_i=161.86 nM$), but not by CGS-21680C ($K_i=2,380 nM$) and DMPX ($K_i=22,367 nM$). However, the specific binding of $[^3H]CGS-21680C$ to the $A_2$ adenosine receptor was not observed. These results suggest that the $A_1$ adenosine heteroreceptor play an important role in evoked ACh release, but the presence of $A_2$ adenosine receptor is not confirmed in this study.

• YAKHAK HOEJI
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• v.41 no.6
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• pp.765-772
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• 1997

Conformational analyses on thromboxane $A_2$ (Tx$A_2$) and thromboxane $A_2$ receptor antagonists (TxRA) were carried out by molecular mechanics method. Based on the assumption that active conformer is the nonintrahydrogen bonding and more stable former of Tx$A_2$ and TxRA, the molecular structural requirements for potent TxA2 receptor antagonists are like below: 1) The distance is 5.0-5.6${\AA}$ between C atom of carboxyl group and S atom of sulfonyl group or C atom which is bonded to hydroxyl group in the active conformers. 2) The putative active conformers of Tx$A_2$and TxRAs are hairpin-like forms.