Serotonergic modulation of synaptic transmission and action potential firing in frog motoneurons.
Frog spinal neurons receive a prominent innervation from the bulbar serotonergic nuclear complex. We used an isolated spinal cord preparation to examine the effect of serotonin (5-hydroxytryptamine, 5-HT) receptor activation on segmental and descending monosynaptic excitatory inputs to frog lumbar motoneurons. Bath-application of 5-HT (0.05 mM) caused a significant reduction in the peak amplitude of segmental EPSP elicited by dorsal root (DR) stimulation (P < 0.05). Contrasting to DR evoked responses 5-HT did not affect the descending monosynaptic EPSP conditioned by ventrolateral column (VLC) stimulation. Recording of the VLC induced EPSP-spike (E-S) field response within the ventral horn motor nucleus disclosed a substantial enhancement in the population discharge of motoneurons upon 5-HT application (P < 0.05). These data suggest the potential importance of serotonergic receptors in motor integration and gaining of motor output in the frog spinal cord.
Ovsepian
Saak V
SV
Department of Neuroscience, School of Medicine, CWRU, Cleveland, OH 44106, USA. saak.ovsepyan@cwru.edu
Vesselkin
Nikolai P
NP
D000200:Action Potentials / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D066298:In Vitro Techniques; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D011895:Rana ridibunda; D012701:Serotonin / Q000494:pharmacology*; D013116:Spinal Cord / Q000166:cytology; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects
D012701:Serotonin