Electrophysiological effects of GABA on cat pancreatic neurons

L. Sha, S. M. Miller, J. H. Szurszewski

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

In mammalian peripheral sympathetic ganglia GABA acts presynaptically to facilitate cholinergic transmission and postsynaptically to depolarize membrane potential. The GABA effect on parasympathetic pancreatic ganglia is unknown. We aimed to determine the effect of locally applied GABA on cat pancreatic ganglion neurons. Ganglia with attached nerve trunks were isolated from cat pancreata. Conventional intracellular recording techniques were used to record electrical responses from ganglion neurons. GABA pressure microejection depolarized membrane potential with an amplitude of 17.4 ± 0.7 mV. Electrically evoked fast excitatory postsynaptic potentials were significantly inhibited (5.4 ± 0.3 to 2.9 ± 0.2 mV) after GABA application. GABA-evoked depolarizations were mimicked by the GABAA receptor agonist muscimol and abolished by the GABAA receptor antagonist bicuculline and the Cl- channel blocker picrotoxin. GABA was taken up and stored in ganglia during preincubation with 1 mM GABA; β-aminobutyric acid application after GABA loading significantly (P < 0.05) increased depolarizing response to GABA (15.6 ± 1.0 vs. 7.8 ± 0.8 mV without GABA preincubation). Immunolabeling with antibodies to GABA, glial cell fibrillary acidic protein, protein gene product 9.5, and glutamic acid decarboxylase (GAD) immunoreactivity showed that GABA was present in glial cells, but not in neurons, and that glial cells did not contain GAD, whereas islet cells did. The data suggest that endogenous GABA released from ganglionic glial cells acts on pancreatic ganglion neurons through GABAA receptors.

Original languageEnglish (US)
Pages (from-to)G324-G331
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume280
Issue number3 43-3
StatePublished - Mar 1 2001

Keywords

  • Electrophysiology
  • Glial cells
  • Immunohistochemistry
  • γ-Aminobutyric acid A receptors
  • γ-aminobutyric acid release

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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