Biomedical subjects

Hideko Yamamoto

Publications and source records attributed to Hideko Yamamoto.

17 recordsLinked to original sources

PubMed2006

Intracisternal A-particle element in the 3' noncoding region of the mu-opioid receptor gene in CXBK mice: a new genetic mechanism underlying differences in opioid sensitivity.

OBJECTIVES: CXBK mice, recombinant inbred mice derived from C57BL/6By and BALB/cBy progenitors, display reduced morphine-induced analgesia. Earlier we reported that CXBK mice expressed a reduced amount of the major transcript, MOR-1 mRNA, of the mu-opioid receptor gene. The CXBK MOR-1 mRNA contains a normal coding region and an abnormally long untranslated region. METHODS AND RESULTS: To identify the nucleotide-sequence difference between the CXBK MOR-1 mRNA and that of the progenitors, we first characterized the 3' untranslated region of the MOR-1 mRNA, which was largely unknown. A 3' rapid amplification of cDNA ends-PCR analysis revealed that the 3' untranslated region of the C57BL/6By MOR-1 mRNA was 10 181 nucleotides transcribed from an exon. Next, we compared the MOR-1 genes in C57BL/6By, CXBK, and BALB/cBy mice, and found a 5293 nucleotide insertion only in CXBK mice. The inserted sequence was a variant of the intracisternal A-particle elements that exist in the mouse genome at approximately 1000 sites. Reverse transcription-PCR analyses revealed that the intracisternal A-particle element was transcribed as a part of the CXBK MOR-1 mRNA. No other differences were found in the MOR-1 mRNA between CXBK and BALB/cBy mice, whereas 100 nucleotides differed between C57BL/6By and CXBK mice aside from the intracisternal A-particle insertion. Finally, CXBK mice displayed reduced morphine responses compared with BALB/cBy mice. CONCLUSIONS: Our data suggest that differences in the MOR-1 3' untranslated region appear to cause the CXBK phenotype. This genetic mechanism underlying the CXBK phenotype may provide good insight into the possible genetic mechanisms underlying individual differences in opioid sensitivity in humans.

3' Untranslated Regions↗

PubMed2006

Repeated methamphetamine administration alters expression of the NMDA receptor channel epsilon2 subunit and kinesins in the mouse brain.

Repeated amphetamine administration results in behavioral sensitization. Behavioral sensitization related to abuse and/or relapse may be associated with stable changes in gene expression. To explore the participating genes, we examined the changes in gene expression levels 24 h or 21 days (long-term withdrawal period) after chronic methamphetamine (METH) treatment for 2 weeks. The expression of several genes related to glutamatergic neural transmission was altered, although changes in the corresponding protein expression were not always consistent with the results for mRNA expression. Of interest, in the frontal cortex of mice treated with METH for 2 weeks, protein expression levels of KIF17 and the N-methyl-D-asparate (NMDA) receptor channel epsilon2 subunit (NRepsilon2) were concomitantly increased. The alteration in expression of these proteins, KIF17 and NRepsilon2, might be a part of the molecular basis of the behavioral sensitization to METH.

Animals↗

PubMed2006

Fluoxetine as a potential pharmacotherapy for methamphetamine dependence: studies in mice.

The monoamine transporters are the main targets of psychostimulant drugs, including methamphetamine (METH) and cocaine. Interestingly, the rewarding effects of cocaine are retained in dopamine transporter (DAT) knockout (KO) mice, while serotonin transporter (SERT) and DAT double KO mice do not exhibit conditioned place preference (CPP) to cocaine. These data suggest that SERT inhibition decreases the rewarding effects of psychostimulants. To further test this hypothesis, in the present study, we investigated the effects of intraperitoneal (i.p.) injections of 20 mg/kg fluoxetine, a selective serotonin reuptake inhibitor (SSRI), on 2 mg/kg METH (i.p.) CPP and locomotor sensitization to 1 mg/kg METH (i.p.) in C57BL/6J mice. Fluoxetine treatment before both the conditioning and preference tests abolished METH CPP. A two-way analysis of variance (ANOVA) revealed that METH CPP tended to be lower in mice pretreated with fluoxetine before the preference test than in control mice pretreated with saline before the preference test. Furthermore, pretreatment with fluoxetine had inhibitory effects on METH-induced locomotor sensitization. These results suggest that fluoxetine, a widely used medication for depression, may be also a useful tool for treating METH dependence.

Amphetamine-Related Disorders↗

PubMed2006

Differential effects of donepezil on methamphetamine and cocaine dependencies.

Donepezil, a choline esterase inhibitor, has been widely used as a medicine for Alzheimer's disease. Recently, a study showed that donepezil inhibited addictive behaviors induced by cocaine, including cocaine-conditioned place preference (CPP) and locomotor sensitization to cocaine. In the present study, we investigated the effects of donepezil on methamphetamine (METH)-induced behavioral changes in mice. In counterbalanced CPP tests, the intraperitoneal (i.p.) administration of 3 mg/kg donepezil prior to 2 mg/kg METH i.p. failed to inhibit METH CPP, whereas pretreatment with 3 mg/kg donepezil abolished the CPP for cocaine (10 mg/kg, i.p.). Similarly, in locomotor sensitization experiments, i.p. administration of 1 mg/kg donepezil prior to 2 mg/kg METH i.p. failed to inhibit locomotor sensitivity to METH, whereas pretreatment with 1 mg/kg donepezil significantly inhibited locomotor sensitivity to cocaine (10 mg/kg, i.p.). These results suggest that donepezil may be a useful tool for treating cocaine dependence but not for treating METH dependence. The differences in the donepezil effects on addictive behaviors induced by METH and cocaine might be due to differences in the involvement of acetylcholine in the mechanisms of METH and cocaine dependencies.

Amphetamine-Related Disorders↗

PubMed2005

G protein-activated inwardly rectifying K+ channel inhibition and rescue of weaver mouse motor functions by antidepressants.

Antidepressants, including tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs), have been widely used for the treatment of not only depression but also other psychiatric disorders, although the molecular mechanisms of the drug effects have not yet been sufficiently revealed. Here, we investigated the in vivo effects of these antidepressants on G protein-activated inwardly rectifying K+ (GIRK) channels, which are important for regulating the excitability of various cells, by using weaver (wv) mice, which have mutant GIRK channels and show abnormal neuronal cell death and motor disturbances. First, we found that a widely used SSRI fluoxetine (also known as Prozac) effectively inhibited wv GIRK2 channels like wild-type GIRK channels, expressed in Xenopus oocytes. Next, we found that weaver motor disturbances were remarkably alleviated by chronic treatment with fluoxetine or desipramine. Furthermore, the chronic fluoxetine treatment substantially suppressed the abnormal neuronal cell death in the weaver mouse cerebellum and pontine nuclei. These results suggest that continuous inhibition of wv GIRK2 channels by a group of antidepressants caused substantial suppression of the neuronal cell death and resulted in improvement of motor abilities in weaver mice. These results provide evidence for in vivo GIRK channel inhibition by a group of antidepressants.

Animals↗

PubMed2005

Low concentrations of nitric oxide (NO) induced cell death in PC12 cells through activation of p38 mitogen-activated protein kinase (p38 MAPK) but not via extracellular signal-regulated kinases (ERK1/2) or c-Jun N-terminal protein kinase (JNK).

Nitric oxide (NO), a highly reactive gaseous molecule, has been previously reported to induce apoptosis-like cell death even at a low concentration in PC12 cells. In this study, we examined NO-induced activation of members of the mitogen-activated protein kinase (MAPK) family, i.e., p38 MAPK, extracellular signal-regulated kinases (ERK1/2), and c-Jun N-terminal protein kinase (JNK). Following the exposure of PC12 cells to an NO donor, (+)-(E)-4-ethyl-2-[hydroxyimino]-5-nitro-3-hexenamide (NOR3; 100 muM), the phosphorylation level of p38 MAPK increased time dependently from 2 to 6 h, but that of both ERK1/2 and JNK did not. Treatment with a p38 MAPK inhibitor SB203580 partially blocked the NOR3-induced cell death. Neither PD98059, U0126 (inhibitors of ERK1/2) nor SP600125 (a specific inhibitor of JNK) treatments had any significant effect on the NOR3-induced cell death. These findings suggest that the activation of a p38 MAPK pathway, but not that of ERK1/2 or JNK, plays an essential role in the apoptosis-like cell death induced by low concentrations of NO.

Analysis of Variance↗

PubMed2005

Methamphetamine modulation of gene expression in the brain: analysis using customized cDNA microarray system with the mouse homologues of KIAA genes.

Amphetamine abuse may be associated with adaptive changes in gene expression. In the present study, we used a newly developed cDNA array system comprising mouse KIAA (mKIAA) cDNA clones to examine changes in gene expression after chronic methamphetamine (MAP) treatment. Mice were daily treated with saline or MAP (2 mg/kg, ip) for 2 weeks. Approximately 800 mKIAA clones were blotted onto a nylon membrane and hybridized with 33P-labeled DNA derived from mRNAs from mouse whole brain. MAP-induced changes were found in several clones by using whole brain mRNA. Since gene expression of Per2, one of the period protein-related proteins, was the most affected by MAP treatment, its expression was further analyzed in pooled hippocampi from 20 mice that had been treated with saline or MAP (2 mg/kg, ip) for 2 weeks. The gene expression and protein expression of Per2 in the hippocampus were increased by MAP treatment. In the hippocampus, Per2 gene expression was under the regulation of circadian rhythm and increases in Per2 expression were due to the phase shift induced by chronic MAP treatment. These findings suggest that unique expression changes of period protein-related proteins in the hippocampus occur in MAP abuse.

Amphetamine-Related Disorders↗

PubMed2005

[Control of craving for methamphetamine: development of scales for dependence and search for medicines for treatment].

Methamphetamine dependence presents a serious problem not only for patients but also for society. Medical treatment has mainly targeted psychotic symptoms such as hallucination and delusion, and ignored the symptoms of craving, which are the major cause of dependence. Therefore, the risk of lapse into methamphetamine reuse remains very high. Although development of both medicines and programs for treatment of craving is needed, progress has been hampered by the lack of appropriate scales for assessing the severity of dependence and craving. On the other hand, recent breakthroughs in genomic sciences and molecular medicine have made it possible to investigate the molecular mechanisms underlying craving in animals. This paper reviews studies on the development of scales for assessing the severity of methamphetamine dependence and craving, together with recent data on candidate medicines for craving treatment in animals. The reliability and validity of the revised Addiction Severity Index -Japanese version (ASI-J) was confirmed after its administration to 100 drug abuse patients. The Craving Index was also newly developed, and its validity for prediction of relapse was confirmed. In animal experiments, fluoxetine, a selective serotonin reuptake inhibitor, was recognized as a candidate medicine for treatment of methamphetamine dependence.

Animals↗

PubMed2004

Functional identification of ASCT1 neutral amino acid transporter as the predominant system for the uptake of L-serine in rat neurons in primary culture.

The uptake of L-serine, a nonessential amino acid known to be transported by the neutral amino acid transporter system ASC, was studied in primary cultures of rat neurons and astrocytes, and compared with that in human embryonic kidney (HEK293) cells transfected with rat ASCT1 cDNA. We first cloned neutral amino acid transporter ASCT1 from rat neurons in primary culture as a transporter candidate for L-serine uptake in the brain. The predicted amino acid sequence from rat ASCT1 exhibited significant homology with mouse and human ASCT1s. The amino acid sequence of rat ASCT1 was 92 and 84% identical to that of mouse and of human ASCT1, respectively. HEK293 cells expressing the rat ASCT1 cDNA showed a saturable dose-dependent and Na(+)-dependent increase in L-[(3)H] serine uptake by high affinity ( K(m) = 67 microM). The substrate selectivity of rat ASCT1 was the same as those of the mouse and human transporter. Northern blot analysis revealed that ASCT1 mRNA was ubiquitously expressed in the brain, with its highest concentration in the striatum and hippocampus. When the uptake of L -[(3)H] serine into rat primary neurons or astrocytes was compared with that of HEK293 cells expressing rat ASCT1 or rat ASCT2 cDNA, the inhibition profile of amino acids for the rat neurons quite resembled that for HEK293 cells expressing rat ASCT1. In contrast, the profile for rat astrocytes was a mixture of that for HEK293 cells expressing rat ASCT1 and that for the cells expressing rat ASCT2. Furthermore, L-[(3)H] serine uptake in neurons was fully Na(+)-dependent. ASCT1 mRNA was expressed in both primary neurons and astrocytes, whereas ASCT2 mRNA was expressed only in astrocytes, as determined by using RT-PCR with primers specific for the rat ASCT1 or rat ASCT2 transporter. Taken together, these findings indicate that ASCT1 predominantly contributes to the uptake of L-serine in primary neurons.

Amino Acid Sequence↗

PubMed2004

Regional differences in extracellular dopamine and serotonin assessed by in vivo microdialysis in mice lacking dopamine and/or serotonin transporters.

Cocaine conditioned place preference (CPP) is intact in dopamine transporter (DAT) knockout (KO) mice and enhanced in serotonin transporter (SERT) KO mice. However, cocaine CPP is eliminated in double-KO mice with no DAT and either no or one SERT gene copy. To help determine mechanisms underlying these effects, we now report examination of baselines and drug-induced changes of extracellular dopamine (DAex) and serotonin (5-HT(ex)) levels in microdialysates from nucleus accumbens (NAc), caudate putamen (CPu), and prefrontal cortex (PFc) of wild-type, homozygous DAT- or SERT-KO and heterozygous or homozygous DAT/SERT double-KO mice, which are differentially rewarded by cocaine. Cocaine fails to increase DAex in NAc of DAT-KO mice. By contrast, systemic cocaine enhances DAex in both CPu and PFc of DAT-KO mice though local cocaine fails to affect DAex in CPu. Adding SERT to DAT deletion attenuates the cocaine-induced DAex increases found in CPu, but not those found in PFc. The selective SERT blocker fluoxetine increases DAex in CPu of DAT-KO mice, while cocaine and the selective DAT blocker GBR12909 increase 5-HT(ex) in CPu of SERT-KO mice. These data provide evidence that (a) cocaine increases DAex in PFc independently of DAT and that (b), in the absence of SERT, CPu levels of 5-HT(ex) can be increased by blocking DAT. Cocaine-induced alterations in CPu DA levels in DAT-, SERT-, and DAT/SERT double-KO mice appear to provide better correlations with cocaine CPP than cocaine-induced DA level alterations in NAc or PFc.

Animals↗

PubMed2004

A possible genetic mechanism underlying individual and interstrain differences in opioid actions: focus on the mu opioid receptor gene.

Individual differences in responses to opioids limit effective pain treatment with these drugs. Identifying the mechanism could help to improve the analgesic effects of them. Since the molecular cloning of the mu opioid receptor (muOR) gene, substantial advances in opioid research have been made, including the discoveries that muOR plays a mandatory role in the analgesic effects of opioids and that the sequence of the muOR gene varies from one individual to another. It is conceivable that the differences in the muOR gene cause individual differences in opioid actions. The present review summarizes the recent advances made in research on human and mouse muOR genes and proposes that the variances in the 3' untranslated region (39-UTR) of the muOR gene might participate in the variability of the opioid response.

Animals↗

PubMed2003

Caspase-independent cell death by low concentrations of nitric oxide in PC12 cells: involvement of cytochrome C oxidase inhibition and the production of reactive oxygen species in mitochondria.

We reported previously that low levels of nitric oxide (NO) induced cell death with properties of apoptosis, including chromatin fragmentation and condensation in undifferentiated PC12 pheochromocytoma cells. The present study demonstrates that cytotoxicity of low concentrations of NO is mediated by inhibition of mitochondrial cytochrome c oxidase and generation of reactive oxygen species (ROS). An NO donor, (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR3) induced cell death even at low concentrations (10-100 microM), whereas peroxynitrite and a peroxynitrite generator, 3-(4-morpholinyl)-sydnonimine (SIN-1), did not have a significant effect on cell viability up to a concentration of 0.5 mM. The NOR3-induced cell death was unaffected by pretreatment with superoxide dismutase (SOD) or its mimetic peroxynitrite scavenger, manganese(III) tetrakis(benzoic acid)porphyrin chloride (Mn-TBAP), or with uric acid. These findings indicate that peroxynitrite does not contribute to this cell death. Furthermore, neither the release of cytochrome c from mitochondrial membranes, the cleavage of poly-ADP ribose polymerase (PARP), nor the activation of caspase-3-like activities was observed. Inhibitors of PARP, benzamide, and aminobenzamide, had no effect on the NOR3-induced cell death. In addition, pretreatment with general or selective caspase inhibitors, benzyloxy-carbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-fmk), N-acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO), and benzyloxycarbonyl-Asp-2,6-dichlorobenzoyloxymethylketone (Z-Asp-Ch(2)-DCB) did not prevent NOR3-induced cell death. Taken together, these findings suggest that cell death induced by NOR3 occurs by a caspase-independent mechanism. In contrast, we found an early increase in mitochondrial H(2)O(2) production during NOR3 exposure using the fluorescent dye 2',7'-dichlorofluorescin-diacetate (DCFH-DA) and dihydrorohdamine123 (DHR123), and these events were accompanied by strong inhibition of cytochrome c oxidase activity in the cells. Furthermore, we observed that several antioxidants, such as ascorbate, glutathione (GSH), cysteine, tetrahydrobiopterin, and dithiothreitol (DTT), all effectively prevented the NOR3-induced cell death. NOR3 treatment decreased the level of total intracellular GSH, but did not affect the activities of antioxidant enzymes SOD, GSH-peroxidase (GPX), and catalase. These results suggest that cell death induced at physiologically low concentrations of NO is mediated by ROS production in mitochondria, most likely resulting from the inhibition of cytochrome c oxidase, with ROS acting as an initiator of caspase-independent cell death.

Animals↗

PubMed2003

Characterization of rapid and high-affinity uptake of L-serine in neurons and astrocytes in primary culture.

The non-essential amino acid L-serine was shown to be required to support the survival of rat cerebellar Purkinje neurons because of lack of the expression of the L-serine biosynthesis enzyme 3-phosphoglycerate dehydrogenase in them. In the present study, we investigated L-[(3)H]serine uptake in primary cultures of neurons and astrocytes from the rat telencephalon. In both neurons and astrocytes, L-[(3)H]serine uptake was dependent on temperature and Na(+) ions, and exhibited a single component of high-affinity uptake sites (K(m)=15.0 and 17.2 micro M for neurons and astrocytes, respectively). Kinetic analysis of L-[(3)H]serine uptake also revealed that the uptake into neurons was faster than that into astrocytes. The selectivity of inhibition by amino acids of the L-[(3)H]serine uptake resembled that of the system ASC transporters ASCT1 and ASCT2. Neutral amino acids L-alanine, L-serine, L-cysteine, and L-threonine strongly inhibited the uptake by both cell types. Furthermore, in astrocytes, but not in neurons, L-valine and L-proline also inhibited L-[(3)H]serine uptake. Neither alpha-methyl aminoisobutyric acid (a system A-specific substrate) nor 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (a system L-specific substrate) inhibited the uptake of L-[(3)H]serine in both neurons and astrocytes. Expression of ASCT transporters in both neurons and astrocytes was examined by use of reverse transcriptase polymerase chain reaction and immunoblot analysis. Whereas transcripts (mRNAs) of both ASCT1 and ASCT2 transporters were detected in astrocytes, only the mRNA of the former subtype was detected in neurons. Immunoblot analysis confirmed the presence of ASCT1 in both neurons and astrocytes. These findings indicate that neurons accumulate a high level of L-serine by using a Na(+)-dependent, high-affinity transport system, operating predominantly through the ASCT1 transporter subtype.

Amino Acid Transport System ASC↗

PubMed2003

Overexpression of V-1 prevents nitric oxide-induced cell death: involvement of enhanced tetrahydrobiopterin biosynthesis.

Previously we reported that the synthesis of catecholamines, dopamine, and noradrenaline was enhanced by overexpression of V-1 protein, a neuronal protein active in the initial stage of development of the rat cerebellum, in the neuronal cell line PC12D, a model of dopamine cells (Yamakuni et al. [1998] J. Biol. Chem. 273:27051-27054). To investigate the physiological role of this protein, we examined the effect of V-1 overexpression on cell toxicity induced by nitric oxide (NO) used at low concentrations. Two clones of PC12D cells overexpressing V-1, transfectants termed V1-46 and V1-69, were significantly more resistant to NOR3 (an NO donor) but not to etoposide (an inhibitor of topoisomerase II)-induced apoptotic cell death than the control cells (termed C-7 and C-9) that had been transfected with the vector alone. The addition of L-DOPA, dopamine, or noradrenaline to the medium did not abolish NOR3-induced cell death in PC12D cells. Moreover, pretreatment of V1-46 and V1-69 cells with L-alpha-methyl-p-tyrosine (alpha-MPT), an inhibitor of tyrosine hydroxylase, to inhibit catecholamine biosynthesis did not affect the resistance to NO toxicity. These results indicate that the catecholamine levels increased by V-1 overexpression did not produce the protection against NOR3-induced toxicity. We further showed that overexpression of V-1 enhanced the synthesis of (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)). In addition, pretreatment with BH(4) or with sepiapterin, which is converted to BH(4) intracellularly, significantly protected PC12D cells in a dose-dependent manner. The increased BH(4) synthesis by V-1 overexpression was dose dependently inhibited by pretreatment with diaminohydroxypyrimidine (DAHP), an inhibitor of GTP-cyclohydrolase I, which is the rate-limiting enzyme for the biosynthesis of BH(4), concomitantly with the loss of protective effect afforded by V-1 overexpression. Furthermore, the addition of BH(4) or sepiapterin to DAHP-pretreated V146 and V1-69 cells restored cell viability. Taken together, these results indicate that V1 protein plays an important role in protection against cell death induced by NO at low levels by promoting the synthesis of BH(4). Moreover, these findings suggest the up-regulation of V1 expression as a possible therapeutic target for protection against the insult of NO-induced oxidative stress.

Animals↗

PubMed2002

Expression of V-1, a novel catecholamine biosynthesis regulatory protein, is enhanced by hypertension in atrial myocytes of Dahl salt-sensitive rats.

V-1 positively controls catecholamine synthetic gene transcription to promote catecholamine production in PC12D cells. In this study, immunohistochemical analysis revealed that in Wistar rats, V-1 immunoreactivity was localized not only in sympathetic axons but also in the cytoplasm of cardiomyocytes, and that the immunoreactivity in atrial myocytes was more intense than that in ventricular myocytes. Western blot analysis also showed that V-1 expression level in the atrium was higher than that in the ventricle of Wistar rat hearts. When Dahl salt-sensitive (DS) rats were fed an 8% NaCl diet after the age of 6 weeks, blood pressure was raised 230mm Hg at 18 weeks. V-1 expression was shown to be increased in the atrial myocytes of these DS rats, but not in the sympathetic axons, when assayed by immunohistochemistry. These results suggest that in normotensive rats, V-1 is preferentially expressed in the cytoplasm of cardiomyocytes in the atrium rather than in the ventricle. It is also suggested that V-1 expression is increased by hypertension in DS rat atrium.

Animals↗

PubMed2002

V-1, a catecholamine biosynthesis regulatory protein, positively controls catecholamine secretion in PC12D cells.

Stably transfected PC12D cell lines overexpressing a catecholamine biosynthesis regulatory protein, V-1, were used to examine the functional role of V-1 in catecholamine secretion. High K(+)-induced dopamine secretion in V-1 overexpressing clones was shown to be markedly potentiated compared with control clones carried with a vector alone. As assayed intracellular calcium concentration ([Ca(2+)](i)) using fura-PE3, V-1 overexpression was observed to enhance high K(+)-elicited [Ca(2+)](i) elevation. Electron microscopic analysis revealed an increase in dense-cored vesicle formation by V-1 overexpression. These results suggest that the enhancement of high K(+)-induced dopamine secretion by V-1 overexpression results from the potentiation of high K(+)-induced [Ca(2+)](i) elevation and the increase in the number of dense-cored vesicles.

Animals↗

PubMed2002

MS-377, a selective sigma receptor ligand, indirectly blocks the action of PCP in the N-methyl-D-aspartate receptor ion-channel complex in primary cultured rat neuronal cells.

MS-377 ((R)-(+)-1-(4-chlorophenyl)-3-[4-(2-methoxyethyl)piperazin-1-yl]methyl-2-pyrrolidinone L-tartrate) is a antipsychotic agent that binds to sigma-1 receptor. MS-377 showed anti-dopaminergic and anti-serotonergic activities and antagonistic action against phencyclidine (PCP)-induced behaviors in an animal model. These anti-psychotic activities of MS-377 are attributable to association with sigma-1 receptor. However, the mechanism by which the sigma-1 receptor ligands exact those numerous effects remains to be elucidated. In the present study, we evaluated the effect of MS-377 on N-methyl-D-aspartate (NMDA) receptor ion-channel complex in primary cultured rat neuronal cells. First, we examined the effect of MS-377 on NMDA-induced Ca2+ influx with fura-2/ AM loaded cells. MS-377 showed no effects on the basal Ca2+ concentration and NMDA-induced Ca2+ influx by itself PCP and SKF-10047 reduced the NMDA-induced increase in intracellular Ca2+ concentration. Pre-incubation of 1 microM MS-377 was found to significantly block the reduction by PCP or SKF-10047 of the NMDA-induced Ca2+ influx. Second, the effect of MS-377 on [3H]MK-801 intact cell binding was examined. PCP, haloperidol and (+)-pentazocine inhibited [3H]MK-801 binding, although MS-377 showed no effect by itself Pre-treatment of MS-377 markedly reversed the inhibition of [3H]MK-801 binding by PCP in a dose-dependent manner. These effects of MS-377 may depend on its affinity for the sigma-1 receptor, because MS-377 is a selective sigma-1 receptor ligand without any affinity for NMDA receptor ion-channel complex. These observations suggest that the MS-377 indirectly modulated the NMDA receptor ion-channel complex, and the anti-psychotic activities of MS-377, in part, are attributable to such on action via sigma-1 receptor.

Animals↗