Abstract
The modulatory effects of serotonin mediated by 5-HT1A receptors in adult spinal motoneurons were investigated by intracellular recordings in a slice preparation from the turtle. In current-clamp mode, activation of 5-HT1A receptors by 8-OH-DPAT led to depolarization and an increase in input resistance in most motoneurons but caused hyperpolarization and a decrease in input resistance in the remaining smaller fraction of cells. When slices were preincubated in medium containing the 5-HT1A receptor antagonist WAY-100635, 8-OH-DPAT had no effect. In voltage-clamp mode, with 1 mM CsCl in the bathing medium, 8-OH-DPAT consistently inhibited a leak current that was sensitive to extracellular acidification and anandamide, a TASK-1 channel blocker. In medium with a low pH, as in the presence of anandamide, 8-OH-DPAT had no effect. Our results show that activation of 5-HT1A receptors contributes to the excitatory effect of serotonin on spinal motoneurons by inhibition of a TASK-1 potassium channel leading to depolarization and increased input resistance.
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 / pharmacology
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Animals
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Arachidonic Acids / pharmacology
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Electrophysiology
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Endocannabinoids
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In Vitro Techniques
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Membrane Potentials / physiology
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Motor Neurons / physiology*
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Nerve Tissue Proteins / drug effects
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Nerve Tissue Proteins / physiology*
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Patch-Clamp Techniques
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Polyunsaturated Alkamides
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Potassium Channel Blockers / pharmacology*
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Potassium Channels / drug effects
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Potassium Channels / physiology*
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Potassium Channels, Tandem Pore Domain*
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Receptor, Serotonin, 5-HT1A / physiology*
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Serotonin / pharmacology
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Serotonin Receptor Agonists / pharmacology
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Spinal Cord / cytology
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Spinal Cord / physiology*
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Turtles / physiology*
Substances
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Arachidonic Acids
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Endocannabinoids
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Nerve Tissue Proteins
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Polyunsaturated Alkamides
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Potassium Channel Blockers
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Potassium Channels
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Potassium Channels, Tandem Pore Domain
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Serotonin Receptor Agonists
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Receptor, Serotonin, 5-HT1A
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potassium channel subfamily K member 3
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Serotonin
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8-Hydroxy-2-(di-n-propylamino)tetralin
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anandamide