• The Korean Journal of Physiology and Pharmacology
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• v.4 no.5
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• pp.355-359
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• 2000

Cocaine induces immediate early gene expression and behavioral changes by blocking dopamine transporters in the terminals of nigrostriatal neurons in the striatum. The pharmacological role of serotonin 2/1C (5HT2/1C) receptors in cocaine-induced expression of zif268 (NGFI-A, egr1 and Krox-24) mRNA, a member of the zinc finger, was investigated using quantitative in situ hybridization histochemistry in vivo. Behavioral alterations induced by cocaine were also monitored in relation with blockade of the receptors. Systemic injection of ritanserin (1 mg/kg, s.c.), a 5HT2/1C receptor antagonist, did not reverse behavioral alterations and zif268 mRNA gene expression induced by 15 mg/kg cocaine, i.p., in the dorsal and ventral striatum. These data indicate that ritanserin-sensitive 5HT2/1C receptors are not necessary for cocaine-induced behavioral alterations and zif268 mRNA gene expression in the striatum.

• Journal of Oriental Neuropsychiatry
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• v.25 no.2
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• pp.191-202
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• 2014

Objectives: The purpose of this study was to examine the anti-depressive effects of BanHaHuBakTang-kami (BHHBT) on an animal model of depression induced by chronic immobility stress. Methods: Mice were treated daily with immobilization stress for 2 hours over a period of 21 days. To examine the effect of BHHBT, we performed behavioral, biochemical and histological analysis to measure immobility time (FST), brain neurotransmitter concentration (HPLC, ELISA), hippocampal damage (H&E staining) and CRF-R1 expression (immunohistochemistry). Results: BHHBT has reduced the immobility time of immobilization stress exposed mice in the forced swimming test. BHHBT has increased the amount of serotonin in the brain. BHHBT has increased the expression level of serotonin in the brain. BHHBT 540 mg/kg were sufficient to prevent tissue damage in the hippocampus region. BHHBT has reduced the expression level of CRF receptors in the hippocampus region. Conclusions: These results suggest that BHHBT may have anti-depressive effects on mice treated with immobilization stress by reducing immobility, increasing brain serotonin concentration and reducing CRF-R1 expression in the hippocampus region.

• The Korean Journal of Nuclear Medicine
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• v.31 no.1
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• pp.9-18
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• 1997

The therapeutic efficacy of antipsychotic drugs is generally attributed to their ability to block dopamine $D_2$ receptors. Classical $D_2$ antagonists are not effective to treat negative symptoms and produce extrapyramidal side effects On the other hand, atypical antipsychotic agents ameliorate negative symptoms without producing extra-pyramidal side effects, and it is reported to be associated with blockade of serotonin $5-HT_2$ receptors. The purpose of this study was to evaluate the effect of risperidone on neuroreceptors in the rat brain by Quantitative autoradiography method. In acute treatment group, risperidone was injected into Peritoneal cavity of male Wistar rats with dose of 0, 0.1, 0.25, 0.5, 1.0 and 2.0mg/kg in each group(5/group), and they were decapitated after 2 hours. In chronic treatment group, risperidone was injected with dose of 0, 0.1, and 1mg/kg(I.P.) for 21 days and decapitated after 24 hours following last treatment. The effect of risperodone on the binding of [$^3H$]spiperone to $5-HT_2$ and $D_2$ receptors were analysed in 4 discrete regions of the striatum, nucleus accumbens, and frontal cortex by quantitative autoradiography Acute treatment with risperidone reduced cortical $5-HT_2$ specific [$^3H$]spiperone binding to 32% of vehicle-treated control. Subcortical $5-HT_2$ specific [$^3H$]spiperone binding was not affected at all dose groups whereas a significant reduction (57%) in $D_2$ specific [$^3H$]spiperone binding was observed in risperidone treated group at doses of 1-2mg/kg. Chronic treatment with risperidone produced a decrease in the maximal number of cortical $5-HT_2$ receptors to 51% and 46% of control in 0.1mg/kg & 1mg/kg treated group respectively. In conclusion, risperidone is a cortical serotonin receptor antagonist with relatively weak antagonistic action on dopamine receptors. These effects oil neuroreceptors may explain the therapeutic effect of risperidone as a atypical antipsychotic agents.

• The Korean Journal of Pharmacology
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• v.29 no.2
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• pp.189-193
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• 1993

Exposure of dissociated cultures from fetal rat brainstem to glutamate for upto 6 h decreased cellular contents of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in a concentration- and time-dependent manner. In addition, glutamate induced lactate dehydrogenase leakage. Tetrodotoxin did not block the effects induced by glutamate. MK-801 $(1{\mu}M)$, an N-methyl-D-aspartate (NMDA) channel blocker, but not 6-cyano-2,3-dihydroxy-7-nitro-quinoxazoline $(CNQX;\;3{\mu}M)$, a non-NMDA receptor antagonist, blocked glutamate-induced effects, indicating that these glutamate-induced responses are mediated through NMDA receptors.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.2
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• pp.71-78
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• 2009

(S)-Carbamic acid 2-[4-(4-fluoro-benzoyl)-piperidin-1-yl]-1-phenyl-ethyl ester hydrochloride (YKP1447) is a novel "atypical" antipsychotic drug which selectively binds to serotonin (5-$HT_{2A}$, Ki=0.61 nM, 5-$HT_{2C}$, Ki=20.7 nM) and dopamine ($D_2$, Ki=45.9 nM, $D_3$, Ki=42.1 nM) receptors with over $10\sim100$-fold selectivity over the various receptors which exist in the brain. In the behavioral studies using mice, YKP1447 antagonized the apomorphine-induced cage climbing ($ED_{50}$=0.93 mg/kg) and DOI-induced head twitch ($ED_{50}$=0.18 mg/kg) behavior. In the dextroamphetamine-induced hyperactivity and conditioned avoidance response (CAR) paradigm in rats, YKP1447 inhibited the hyperactivity induced by amphetamine ($ED_{50}$=0.54 mg/kg) and the avoidance response ($ED_{50}$=0.48 mg/kg); however, unlike other antipsychotic drugs, catalepsy was observed only at much higher dose ($ED_{50}$=68.6 mg/kg). Based on the CAR and catalepsy results, the therapeutic index (TI) value for YKP1447 is over 100 (i.p.). These results indicate that YKP1447 has an atypical profile and less undesirable side effects than currently available drugs.

• Genomics & Informatics
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• v.5 no.2
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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.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.5
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• pp.361-367
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• 2000

Cocaine functions as indirect dopamine and serotonin (5-hydroxytryptamine, 5HT) agonists and induces genomic and behavioral alterations in the striatum. Previously we demonstrated that ritanserin, a 5HT2/1C receptor antagonist, is not responsible for cocaine-induced behavioral alterations and zif268 mRNA gene expression in the striatum (see the previous paper in this issue). In this study, it was hypothesized that dopamine and 5HT2/1C receptors are required for cocaine-induced behavioral alterations and c-fos and zif268 mRNA expression. This hypothesis was addressed by infusing amperozide which antagonizes both 5HT2/1C and dopamine receptors and was analyzed using the quantitative in situ hybridization histochemistry in vivo. Systemic injection of amperozide (5 mg/kg, s.c.) significantly blocked increase in behavior, c-fos and zif268 mRNA expression induced by 15 mg/kg cocaine, i.p., in the dorsal striatum. These data suggest that dopamine and 5HT2/1C receptors are necessary for cocaine-induced behavioral alterations and immediate early gene expression in the dorsal striatum.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.1
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• pp.65-70
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• 2012

Synaptic long-term potentiation (LTP) and long-term depression (LTD) have been studied as mechanisms of ocular dominance plasticity in the rat visual cortex. Serotonin (5-hydroxytryptamine, 5-HT) inhibits the induction of LTP and LTD during the critical period of the rat visual cortex (postnatal 3~5 weeks). However, in adult rats, the increase in 5-HT level in the brain by the administration of the selective serotonin reuptake inhibitor (SSRI) fluoxetine reinstates ocular dominance plasticity and LTP in the visual cortex. Here, we investigated the effect of 5-HT on the induction of LTP in the visual cortex obtained from 3- to 10-week-old rats. Field potentials in layer 2/3, evoked by the stimulation of underlying layer 4, was potentiated by theta-burst stimulation (TBS) in 3- and 5-weekold rats, then declined to the baseline level with aging to 10 weeks. Whereas 5-HT inhibited the induction of LTP in 5-week-old rats, it reinstated the induction of N-methyl-D-aspartate receptor (NMDA)-dependent LTP in 8- and 10-week-old rats. Moreover, the selective SSRI citalopram reinstated LTP. The potentiating effect of 5-HT at 8 weeks of age was mediated by the activation of 5-$HT_2$ receptors, but not by the activation of either 5-$HT_{1A}$ or 5-$HT_3$ receptors. These results suggested that the effect of 5-HT on the induction of LTP switches from inhibitory in young rats to facilitatory in adult rats.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.1
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• pp.31-38
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• 2006

Fluoxetine, widely used for the treatment of depression, is known to be a selective serotonin reuptake inhibitor (SSRI), however, there are also reports that fluoxetine has direct effects on several receptors. Employing whole-cell patch clamp techniques in rat brain slice, we studied the effects of fluoxetine on corticostriatal synaptic transmission by measuring the change in spontaneous excitatory postsynaptic currents (sEPSC). Acute treatment of rat brain slice with fluoxetine ($10{\mu}M$) significantly decreased the amplitude of sEPSC ($8.1{\pm}3.3$%, n=7), but did not alter its frequency ($99.1{\pm}4.7$%, n=7). Serotonin ($10{\mu}M$) also significantly decreased the amplitude ($81.2{\pm}3.9$%, n=4) of sEPSC, but did not affect its frequency ($105.8{\pm}8.0$, n=4). The effect of fluoxetine was found to have the same trend as that of serotonin. We also found that the inhibitory effect of fluoxetine on sEPSC amplitude ($93.0{\pm}1.9$%, n=8) was significantly blocked, but not serotonin ($84.3{\pm}1.6$%, n=4), when the brain slice was incubated with p-chloroamphetamine ($10{\mu}M$), which depletes serotonin from the axon terminals and blocks its reuptake. These results suggest that fluoxetine inhibits corticostriatal synaptic transmission through postsynaptic, and that these effects are exerted through both serotonin dependent and independent mechanism.

• The Korean Journal of Physiology and Pharmacology
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• v.23 no.4
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• pp.271-279
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• 2019

The lamina II, also called the substantia gelatinosa (SG), of the trigeminal subnucleus caudalis (Vc), is thought to play an essential role in the control of orofacial nociception. Glycine and serotonin (5-hydroxytryptamine, 5-HT) are the important neurotransmitters that have the individual parts on the modulation of nociceptive transmission. However, the electrophysiological effects of 5-HT on the glycine receptors on SG neurons of the Vc have not been well studied yet. For this reason, we applied the whole-cell patch clamp technique to explore the interaction of intracellular signal transduction between 5-HT and the glycine receptors on SG neurons of the Vc in mice. In nine of 13 neurons tested (69.2%), pretreatment with 5-HT potentiated glycine-induced current ($I_{Gly}$). Firstly, we examined with a $5-HT_1$ receptor agonist (8-OH-DPAT, $5-HT_{1/7}$ agonist, co-applied with SB-269970, $5-HT_7$ antagonist) and antagonist (WAY-100635), but $5-HT_1$ receptor agonist did not increase $I_{Gly}$ and in the presence of $5-HT_1$ antagonist, the potentiation of 5-HT on $I_{Gly}$ still happened. However, an agonist (${\alpha}$-methyl-5-HT) and antagonist (ketanserin) of the $5-HT_2$ receptor mimicked and inhibited the enhancing effect of 5-HT on $I_{Gly}$ in the SG neurons, respectively. We also verified the role of the $5-HT_7$ receptor by using a $5-HT_7$ antagonist (SB-269970) but it also did not block the enhancement of 5-HT on $I_{Gly}$. Our study demonstrated that 5-HT facilitated $I_{Gly}$ in the SG neurons of the Vc through the $5-HT_2$ receptor. The interaction between 5-HT and glycine appears to have a significant role in modulating the transmission of the nociceptive pathway.