GABA and responses to GABA in the stomatogastric ganglion of the crab Cancer borealis

Andrew M. Swensen, Jorge Golowasch, Andrew E. Christie, Melissa J. Coleman, Michael P. Nusbaum, Eve Marder

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

The multifunctional neural circuits in the crustacean stomatogastric ganglion (STG) are influenced by many small-molecule transmitters and neuropeptides that are co-localized in identified projection neurons to the STG. We describe the pattern of γ-aminobutyric acid (GABA) immunoreactivity in the stomatogastric nervous system of the crab Cancer borealis and demonstrate biochemically the presence of authentic GABA in C. borealis. No STG somata show GABA immunoreactivity but, within the stomatogastric nervous system, GABA immunoreactivity co-localizes with several neuropeptides in two identified projection neurons, the modulatory proctolin neuron (MPN) and modulatory commissural neuron 1 (MCN1). To determine which actions of these neurons are evoked by GABA, it is necessary to determine the physiological actions of GABA on STG neurons. We therefore characterized the response of each type of STG neuron to focally applied GABA. All STG neurons responded to GABA. In some neurons, GABA evoked a picrotoxin-sensitive depolarizing, excitatory response with a reversal potential of approximately -40mV. This response was also activated by muscimol. In many STG neurons, GABA evoked inhibitory responses with both K+- and Cl- -dependent components. Muscimol and β-guanidinopropionic acid weakly activated the inhibitory responses, but many other drugs, including bicuculline and phaclofen, that act on vertebrate GABA receptors were not effective. In summary, GABA is found in projection neurons to the crab STG and can evoke both excitatory and inhibitory actions on STG neurons.

Original languageEnglish (US)
Pages (from-to)2075-2092
Number of pages18
JournalJournal of Experimental Biology
Volume203
Issue number14
StatePublished - Jul 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science

Keywords

  • Cancer borealis
  • Crab
  • Crustacean
  • GABA receptor
  • Projection neurone
  • Stomatogastric ganglion

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