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Updated: Feb 23, 2026

In Vivo Intracellular Recording of Type-Identified Rat Spinal Motoneurons During Trans-Spinal Direct Current Stimulation
Published on: May 11, 2020
Serotonin depolarizes cat spinal motoneurons in situ and decreases motoneuron afterhyperpolarizing potentials
1Department of Veterinary and Comparative Anatomy, College of Veterinary Medicine, Washington State University, Pullman 99164-6520.
Abstract:
Mechanisms by which serotonin produces a long duration facilitation of spinal motoneuron excitability were investigated in decerebrate cats using intracellular recording combined with extracellular microiontophoresis. Serotonin was found to produce a slowly developing, small amplitude, long duration depolarization of the spinal motoneurons. This finding conflicts with early reports of serotonin-induced rapid hyperpolarization of cat spinal motoneurons, but exactly corresponds to more recent findings in rat facial motoneurons. The depolarization was accompanied by an increase in motoneuron excitability and an increase in membrane input resistance. In addition, serotonin reduced the motoneuron postspike afterhyperpolarizing potential in several motoneurons even through depolarization consistently occurred.
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