Abstract
Effects of 5-hydroxytryptamine (5-HT) on inhibitory synaptic transmission in the rat dorsolateral septal nucleus (DLSN) were examined by conventional intracellular and voltage-clamp recording methods. 5-HT (1-30 microM) depressed the monosynaptic fast IPSC evoked by local stimulation of the DLSN in the presence of DNQX, AP5 and CGP 55845A. CP 93129, a selective 5-HT1B receptor agonist, depressed the fast IPSC. The 5-HT-induced depression of the fast IPSC was attenuated by SB 216641, a selective antagonist for 5-HT1B receptors. 5-HT did not change the inward currents mediated by GABAA receptors, suggesting that 5-HT presynaptically inhibited the fast IPSC. 5-HT and CP 93129 depressed the frequency of miniature fast IPSPs (mIPSPs) without changing their amplitudes. Neither a selective protein kinase A inhibitor, H-89, nor a selective protein kinase C inhibitor, calphostin C, blocked the 5-HT-induced depression of the fast IPSC. N-Ethylmaleimide (NEM) blocked the 5-HT-induced depression of the evoked IPSC. These results suggest that activation of presynaptic 5-HT1B receptors depresses the release of GABA via a pertussis toxin (PTX)-sensitive G-protein in the rat DLSN.
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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Analysis of Variance
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Animals
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Benzamides / pharmacology
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Biphenyl Compounds / pharmacology
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Calcium Channel Blockers / pharmacology
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Dose-Response Relationship, Drug
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Drug Interactions
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Enzyme Inhibitors / pharmacology
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Excitatory Amino Acid Antagonists / pharmacology
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GABA Agonists / pharmacology
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GABA Antagonists / pharmacology
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In Vitro Techniques
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Male
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Membrane Potentials / physiology
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Muscimol / pharmacology
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Neural Inhibition / physiology*
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Neurons / physiology*
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Oxadiazoles / pharmacology
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Patch-Clamp Techniques / methods
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Pertussis Toxin / pharmacology
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Phosphinic Acids / pharmacology
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Piperazines / pharmacology
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Presynaptic Terminals / physiology*
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Propanolamines / pharmacology
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Pyridines / pharmacology
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Pyrroles / pharmacology
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Quinoxalines / pharmacology
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Rats
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Rats, Wistar
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Receptor, Serotonin, 5-HT1B / physiology*
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Septal Nuclei / cytology*
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Serotonin / pharmacology
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Serotonin Antagonists / pharmacology
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Serotonin Receptor Agonists / pharmacology
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Synaptic Transmission
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gamma-Aminobutyric Acid / pharmacology
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omega-Agatoxin IVA / pharmacology
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omega-Conotoxin GVIA / pharmacology
Substances
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Benzamides
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Biphenyl Compounds
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Calcium Channel Blockers
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Enzyme Inhibitors
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Excitatory Amino Acid Antagonists
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GABA Agonists
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GABA Antagonists
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N-(3-(2-dimethylamino)ethoxy-4-methoxyphenyl)-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-carboxamide
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Oxadiazoles
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Phosphinic Acids
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Piperazines
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Propanolamines
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Pyridines
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Pyrroles
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Quinoxalines
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Receptor, Serotonin, 5-HT1B
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Serotonin Antagonists
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Serotonin Receptor Agonists
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omega-Agatoxin IVA
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3-(1,2,5,6-tetrahydropyrid-4-yl)pyrrolo(3,2-b)pyrid-5-one
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CGP 55845A
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Muscimol
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Serotonin
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gamma-Aminobutyric Acid
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FG 9041
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N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide
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omega-Conotoxin GVIA
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Pertussis Toxin
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BRL 15572