5-Hydroxytryptophan (5-HTP) augments spontaneous and evoked phrenic motoneuron discharge in spinalized rats

Neurosci Lett. 1992 Jul 6;141(1):75-8. doi: 10.1016/0304-3940(92)90338-8.


Experiments on anesthetized, spinalized rats were conducted to determine the effects of systemic 5-hydroxytryptophan (5-HTP) administration on: (1) spontaneous phrenic nerve activity and (2) evoked phrenic responses to short latency, non-serotonergic synaptic inputs elicited by electrical stimulation of lateral funiculus. 5-HTP augmented spontaneous phrenic activity and allowed expression of a second, longer latency evoked response. Both effects were antagonized by methysergide. Our results suggest that spinal serotonin increases the efficacy of synaptic inputs to phrenic motoneurons.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 5-Hydroxytryptophan / pharmacology*
  • Animals
  • Decerebrate State*
  • Evoked Potentials / physiology
  • Methysergide / pharmacology
  • Motor Neurons / drug effects*
  • Phrenic Nerve / cytology
  • Phrenic Nerve / drug effects
  • Rats
  • Rats, Inbred Strains


  • 5-Hydroxytryptophan
  • Methysergide