Abstract
New data show that 5-hydroxytryptamine (5-HT) neurons of the dorsal raphe nucleus (DRN) are subject to feedback control from 5-HT2 receptors, but the circuitry involved is uncertain. This study investigated whether 5-HT2 receptor agonism activates DRN gamma-aminobutyric acid (GABA) neurons, which are known to inhibit neighbouring 5-HT neurons. Systemic administration of the 5-HT2 receptor agonist, DOI, caused a striking increase in Fos-immunoreactivity in the DRN. This effect was abolished by the 5-HT2 antagonists ritanserin and MDL 100907, but not SB 206553, indicating the involvement of 5-HT2A receptors. Importantly, DOI-induced Fos-immunoreactivity in the DRN was extensively colocalized in GAD67-immunoreactive neurons. These findings suggest that activated local GABA neurons may play an important role in 5-HT2 receptor-mediated feedback control of DRN 5-HT neurons.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amphetamines / pharmacology
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Analysis of Variance
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Animals
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Cell Count
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Feedback / physiology*
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Fluorobenzenes / pharmacology
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Gene Expression Regulation / drug effects
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Glutamate Decarboxylase / metabolism
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Immunohistochemistry / methods
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Isoenzymes / metabolism
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Male
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Neurons / drug effects
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Neurons / metabolism*
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Oncogene Proteins v-fos / metabolism
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Piperidines / pharmacology
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Raphe Nuclei / cytology*
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Raphe Nuclei / drug effects
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Raphe Nuclei / metabolism
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Rats
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Rats, Sprague-Dawley
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Serotonin / physiology*
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Serotonin Antagonists / pharmacology
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Serotonin Receptor Agonists / pharmacology
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gamma-Aminobutyric Acid / metabolism*
Substances
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Amphetamines
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Fluorobenzenes
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Isoenzymes
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Oncogene Proteins v-fos
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Piperidines
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Serotonin Antagonists
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Serotonin Receptor Agonists
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Serotonin
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gamma-Aminobutyric Acid
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Glutamate Decarboxylase
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glutamate decarboxylase 1
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volinanserin
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4-iodo-2,5-dimethoxyphenylisopropylamine