Actions of 5-hydroxytryptamine on myenteric neurons in guinea pig gastric antrum

Am J Physiol. 1992 Dec;263(6 Pt 1):G838-46. doi: 10.1152/ajpgi.1992.263.6.G838.


Intracellular recording methods were used to study the actions of 5-hydroxytryptamine (5-HT) on 257 myenteric neurons in the guinea pig gastric antrum. Application of 5-HT caused three types of postsynaptic responses. A fast-activating depolarizing response was accompanied by a decreased input resistance and desensitized quickly to repeated applications. It was mediated by a 5-HT3 receptor. A slowly activating depolarization, accompanied by an increase in the input resistance and enhancement of the excitability, was mainly observed in after hyperpolarizing/type 2 neurons. It was suppressed by the prokinetic benzamide compound renzapride, while classical 5-HT1-4 receptor antagonists had no effect, suggesting the involvement of a 5-HT1p receptor as described in small intestinal neurons. A long-lasting hyperpolarizing response, accompanied by a decreased input resistance, was observed in a small subset of neurons. This response seemed to be mediated by a 5-HT1a receptor. Superfusion of 5-HT caused a dose-dependent inhibition of the stimulus-evoked nicotinic cholinergic fast excitatory postsynaptic potential (EPSP), which was mediated by a presynaptic 5-HT1a receptor. 5-HT also presynaptically inhibited the slow EPSP.

Publication types

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

MeSH terms

  • Animals
  • Electrophysiology
  • Guinea Pigs
  • Male
  • Myenteric Plexus / cytology
  • Myenteric Plexus / drug effects*
  • Neural Inhibition
  • Neurons / drug effects*
  • Neurons / physiology
  • Pyloric Antrum / drug effects*
  • Pyloric Antrum / physiology
  • Reaction Time
  • Serotonin / pharmacology*
  • Synapses / drug effects
  • Synapses / physiology


  • Serotonin