Abstract
Using extracellular ex vivo recording we studied changes in the reactivity of rat frontal cortical neurons to the 5-HT(1A), 5-HT(2) and 5-HT(4) receptor agonists (+/-)-2-dipropyloamino-8-hydroxy-1,2,3,4-tetrahydronaphtalene hydrobromide (8-OH-DPAT), (+/-)-2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) and zacopride, respectively, induced by a repeated treatment with imipramine or citalopram. Rats were treated with imipramine or citalopram for 14 days (10 mg/kg p.o.) twice daily. Frontal cortical slices were prepared 2 days after the last drug administration. Spontaneous epileptiform discharges were induced in slices by perfusion with a medium devoid of Mg(2+) ions and with added picrotoxin (30 microM). While the application of 2 microM 8-OH-DPAT resulted in a reversible decrease of the discharge frequency, in the presence of DOI (1 microM) or zacopride (5 microM), the discharge frequency was increased. Both repeated imipramine and citalopram enhanced the effect of the activation of 5-HT(1A) receptor and attenuated the effect related to 5-HT(2) receptor activation, while the effect of the activation of 5-HT(4) receptor remained unchanged. Moreover, imipramine, but not citalopram, induced a reduction of epileptiform discharge frequency and an increase of the time of occurrence of epileptiform activity. These data indicate that antidepressants enhance the 5-HT-mediated inhibition in neuronal circuitry of the frontal cortex.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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8-Hydroxy-2-(di-n-propylamino)tetralin / administration & dosage
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8-Hydroxy-2-(di-n-propylamino)tetralin / pharmacokinetics
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Adaptation, Physiological*
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Administration, Topical
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Amphetamines / administration & dosage
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Amphetamines / pharmacokinetics
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Animals
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Benzamides / administration & dosage
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Benzamides / pharmacokinetics
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Benzimidazoles / administration & dosage
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Benzimidazoles / pharmacokinetics
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Bridged Bicyclo Compounds, Heterocyclic / administration & dosage
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Bridged Bicyclo Compounds, Heterocyclic / pharmacokinetics
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Citalopram / administration & dosage
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Citalopram / pharmacokinetics*
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Cortical Synchronization / drug effects
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Dose-Response Relationship, Drug
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Frontal Lobe / cytology*
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Frontal Lobe / drug effects*
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Frontal Lobe / physiology
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Imipramine / administration & dosage
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Imipramine / pharmacokinetics*
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Male
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Neurons / drug effects
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Neurons / physiology
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Piperazines / administration & dosage
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Piperazines / pharmacokinetics
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Pyridines / administration & dosage
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Pyridines / pharmacokinetics
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Rats
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Rats, Wistar
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Receptor, Serotonin, 5-HT1A / drug effects*
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Receptor, Serotonin, 5-HT1A / physiology
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Receptors, Serotonin, 5-HT2 / drug effects*
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Receptors, Serotonin, 5-HT2 / physiology
Substances
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Amphetamines
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Benzamides
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Benzimidazoles
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Bridged Bicyclo Compounds, Heterocyclic
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Piperazines
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Pyridines
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Receptors, Serotonin, 5-HT2
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Citalopram
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Receptor, Serotonin, 5-HT1A
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DAU 6285
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N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide
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8-Hydroxy-2-(di-n-propylamino)tetralin
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zacopride
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Imipramine
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4-iodo-2,5-dimethoxyphenylisopropylamine