Enhancement by serotonin of tonic vibration and stretch reflexes in the decerebrate cat

J. S. Carp, W. Z. Rymer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


The effects of pharmacological manipulation of serotonergic systems on spinal reflexes were determined in the unanesthetized decerebrate cat. The prolonged motor output that continues after cessation of high frequency longitudinal tendon vibration was strongly enhanced by the serotonin reuptake blocker fluoxetine and the serotonin precursor 5-hydroxytryptophan, and was decreased by the serotonin receptor antagonist methysergide. In addition, both dynamic and static stretch reflex stiffness was markedly increased by fluoxetine and 5-hydroxytryptophan, while methysergide produced a decrease in stretch reflex stiffness. These powerful effects on tonic vibration and stretch reflexes could not be explained by drug-induced alterations in muscle spindle primary afferent discharge. In light of other recent results on serotonin-mediated effects on motoneurons, we believe that the effects of these agents result from modification of an intrinsically mediated prolonged depolarization of spinal neurons. However, the possibility that these drugs modify longlasting discharge in associated interneuronal pathways cannot be ruled out.

Original languageEnglish (US)
Pages (from-to)111-122
Number of pages12
JournalExperimental Brain Research
Issue number1
StatePublished - Mar 1986


  • Bistable neuronal behavior
  • Serotonin
  • Spinal cord
  • Stretch reflex
  • Tonic vibration reflex

ASJC Scopus subject areas

  • Neuroscience(all)

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