| Project/Area Number |
10672148
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
応用薬理学・医療系薬学
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| Research Institution | Toyama Medical and Pharmaceutical University |
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Principal Investigator |
MATSUMOTO Kinzo Institute of Natural Medicine, Toyama Medical and Pharmaceutical University Associate Professor, 和漢薬研究所, 助教授 (10114654)
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| Co-Investigator(Kenkyū-buntansha) |
TOHDA Michihisa Institute of Natural Medicine, Toyama Medical and Pharmaceutical University Assistant Professor, 和漢薬研究所, 助手 (20207525)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1999: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1998: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | Neurosteroids / Social isolation stress / Majonoside-R2 / Psychological stress / GABAィイD2AィエD2 receptors / Endogenous benzodiazepine receptor ligand / Pentobarbital sleep / Fluoxetine / Neurosteroids / social isolation stress / psychological stress / majonoside-R2 / lipid peroxidation / 末梢性ベンゾジアゼピン受容体 / SKF105,111 / socialisolation stress / fluoxetine / 中枢神経系 |
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| Research Abstract |
This study aimed to clarify a role of the neurosteroid system in the regulation of GABAィイD2AィエD2 receptor in normal and psychologically stressed animals, and to obtain basic information on whether the neurosteroid system can be a target for developing new psychotropic drugs. Mice were exposed to social isolation stress (SIS) or psychological stress with communication box paradigm (SCBP). Group-housed mice (GR) were used as normal control.
SIS decreased the brain content of the positive allosteric GABAィイD2AィエD2 receptor modulator allopregnanolone (ALLO), and shortened pentobarbital (PB) sleep. Fluoxetine reversed SIS-induced changes in the ALLO content and PB sleep without affecting these parameters in GR. Blockade of ALLO biosynthesis shortened PB- and muscimol-induced sleep, and suppressed GABAィイD2AィエD2-gated current in the pyramidal neurons. DBI, an endogenous peptide capable of interacting with central and mitochondrial benzodiazepine receptors (MBR), shortened PB sleep in GR without
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affecting socially isolated mice. SIS suppressed DBI gene expression in the hypothalamus. The MBR agonist FGIN-l-27 normalized PB sleeping time in socially isolated mice and the effect was antagonized by the a negative allosteric GABAィイD2AィエD2 receptor modulator pregnenolone sulfate (PS). SCBP increased lipid peroxidation products in the brain via activating neuronal nitric oxide synthase. Majonoside-R2 suppressed this increase in a PS reversible manner.
These results demonstrate that ALLO has a permissive role in the GABAergic neurotransmission in the normal animals and that the decrease in the ALLO content impairs the GABAィイD2AィエD2 receptor function, resulting in a psycho-pathophysiological state. Moreover, it is likely that SIS causes a decrease in PB sleep partly by increasing DBI activity and that DBI gene expression in the hypothalamus is regulated by a negative feedback mechanism. Moreover, the involvement of neurosteroids in the effect of fluoxetine and majonoside-R2 suggests that the neurosteroid system could be a new target for psychotropic drug development. Less
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