Facilitation of masseter EMG and masseteric (jaw-closure) reflex by serotonin in behaving cats

L. E. Ribeiro-do-Valle, C. W. Metzler, B. L. Jacobs

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


The trigeminal motor nucleus (MoV) contains the somata of the motoneurons that control jaw position and jaw movements. This nucleus is of neurochemical interest because it recieves a dense serotonergic input. We examined the effects of application oof serotonin or fluoxetine, a serotonin reuptake blocker, into this nucleus on the spontaneous or reflex (jaw-closure) electrical activity of the masseter muscle in behaving cats. Serotonin produced a clearcut enhancement of both spontaneous and reflex activities. This action was attenuated by previous systemic injection of the serotonin receptor antagonist methysergide. The effect was mimicked to a certain extent by fluoxetine. These data provide evidence that the serotonergic input to MoV exerts a general facilitatory influence on masseter motoneurons activity.

Original languageEnglish (US)
Pages (from-to)197-204
Number of pages8
JournalBrain Research
Issue number2
StatePublished - Jun 7 1991

All Science Journal Classification (ASJC) codes

  • Clinical Neurology
  • Molecular Biology
  • General Neuroscience
  • Developmental Biology


  • Jaw-closure reflex
  • Masseter electromyogram
  • Masseteric reflex
  • Mesencephalic trigeminal nucleus
  • Serotonin
  • Trigeminal motor nucleus


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