5-HT and 5-HT-SO4, but not tryptophan or 5-HIAA levels in single feeding neurons track animal hunger state

J Neurochem. 2008 Mar;104(5):1358-63. doi: 10.1111/j.1471-4159.2007.05084.x. Epub 2007 Nov 23.


Serotonin (5-HT) is an intrinsic modulator of neural network excitation states in gastropod molluscs. 5-HT and related indole metabolites were measured in single, well-characterized serotonergic neurons of the feeding motor network of the predatory sea-slug Pleurobranchaea californica. Indole amounts were compared between paired hungry and satiated animals. Levels of 5-HT and its metabolite 5-HT-SO4 in the metacerebral giant neurons were observed in amounts approximately four-fold and two-fold, respectively, below unfed partners 24 h after a satiating meal. Intracellular levels of 5-hydroxyindole acetic acid and of free tryptophan did not differ significantly with hunger state. These data demonstrate that neurotransmitter levels and their metabolites can vary in goal-directed neural networks in a manner that follows internal state.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Feeding Behavior / physiology*
  • Ganglia, Invertebrate / chemistry
  • Ganglia, Invertebrate / metabolism
  • Hunger / physiology*
  • Hydroxyindoleacetic Acid / analysis
  • Hydroxyindoleacetic Acid / metabolism*
  • Nerve Net / chemistry
  • Nerve Net / metabolism
  • Neurons / chemistry
  • Neurons / metabolism*
  • Pleurobranchaea
  • Satiation / physiology
  • Serotonin / analogs & derivatives*
  • Serotonin / analysis
  • Serotonin / metabolism*
  • Tryptophan / analysis
  • Tryptophan / metabolism*


  • 5-hydroxytryptamine O-sulfate
  • Serotonin
  • Hydroxyindoleacetic Acid
  • Tryptophan