5-HT1A receptors modulate small-conductance Ca2+-activated K+ channels

✍ Scribed by Morten Grunnet; Thomas Jespersen; Jean-François Perrier

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 393 KB
• Volume: 78
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.20318

✦ Synopsis

Abstract

Small‐conductance calcium‐activated potassium channels (SK) are responsible for the medium afterhyperpolarisation (mAHP) following action potentials in neurons. Here we tested the ability of serotonin (5‐HT) to modulate the activity of SK channels by coexpressing 5‐HT~1A~ receptors with different subtypes of SK channels (SK1, SK2, and SK3) in Xenopus laevis oocytes. SK channels were activated by intracellular injection of Cd^2+^. Subsequent activation of 5‐HT~1A~ receptors by 8‐OH‐DPAT always produced an inhibition of the SK current, showing the existence of a specific pathway between the receptor and the ion channel. To investigate the physiological relevance of this pathway, we characterized the mAHP present after action potentials in spinal motoneurons recorded in a slice preparation from the lumbar spinal cord of the adult turtle. By performing current and voltage clamp recordings, we showed that 8‐OH‐DPAT specifically inhibited the fraction of the AHP mediated by SK channels. We conclude that the activity of SK channels is modulated by activation of serotonergic receptors. © 2004 Wiley‐Liss, Inc.