Serotonin depletion in vivo inhibits the branching of olfactory projection neurons in the lobster deutocerebrum

J. M. Sullivan, J. L. Benton, B. S. Beltz

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37 Scopus citations


Serotonin depletion during embryogenesis has been shown previously to retard the growth of the olfactory and accessory lobes of the lobster deutocerebrum (Benton et al., 1997). The present study was undertaken to determine whether morphological changes in the interneurons innervating these lobes contribute to this growth retardation. We examined the effects of in vivo serotonin depletion using 5,7-dihydroxytryptamine (5,7-DHT) on the morphology of the olfactory projection neurons, one of two major classes of interneurons that innervate both lobes. Intracellular dye fills of olfactory projection neurons in normal embryos showed that each neuron extensively innervates either the olfactory or accessory lobe before projecting to neuropil regions in the protocerebrum. In embryos injected with 5,7-DHT, however, the deutocerebral arbors of 13.5% of the olfactory projection neurons examined were either markedly reduced compared with normal neurons or absent. Affected neurons also exhibited a number of additional aberrant morphological features suggesting that these neurons represent cells that were affected during their initial morphogenesis. Olfactory projection neurons with aberrant morphologies were also encountered, although less frequently (7.5% of the neurons examined), in control (sham-injected) embryos indicating that the sham injections can affect the development of the brain. This observation provides insights into the nature of effects seen in control embryos in previous experiments (Benton et al., 1997). The results of the present study indicate that in vivo serotonin depletion inhibits the branching of olfactory projection neurons and suggest, therefore, that one of the functions of serotonin during normal development is to promote the ingrowth of these neurons into the deutocerebral neuropils.

Original languageEnglish (US)
Pages (from-to)7716-7721
Number of pages6
JournalJournal of Neuroscience
Issue number20
StatePublished - Oct 15 2000
Externally publishedYes


  • 5,7-dihydroxytryptamine
  • Deutocerebrum
  • Development
  • Homarus americanus
  • Lobster
  • Olfaction
  • Olfactory projection neuron
  • Serotonin

ASJC Scopus subject areas

  • General Neuroscience


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