Inhibitory effect of baclofen on GABA-induced depolarization and GABA- activated current in primary sensory neurons

J. Q. Si, Z. W. Li, H. Z. Hu, X. P. Zhou, B. C. Guan

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18 Scopus citations

Abstract

It has been established that GABA(A) and GABA(B) receptors can exist separately and/or co-exist in the membrane of dorsal root ganglion neurons. In our previous investigation it has been shown that co-existence of these two kinds of receptors is about 80% of the neurons examined (20/25). The present study was aimed to explore whether the activation of these two kinds of receptors could interact with each other using intracellular and whole- cell patch-clamp recordings. Baclofen, a specific GABA(B) receptor agonist, was found to exert negative modulatory effects on the responses mediated by GABA(A) receptor. In experiments with intracellular recording, GABA (03-1000 μM)- and muscimol (00-1000 μM)-induced depolarization was attenuated markedly and reversibly by preapplication of baclofen (100 μM) (15/21 and 17/21, respectively). In whole-cell patch-clamp recordings GABA (100 μM) and two specific GABA(A) receptor agonists, muscimol (10 μM) and isoguvacine (50 μM), activated currents were inhibited markedly by preapplication of baclofen 30 s or more and the inhibition was concentration dependent (1-100 μM baclofen) and reversible. The possible mechanisms underlying the inhibition by baclofen of the responses mediated by GABA(A) receptor and the physiological significance implicated are discussed.

Original languageEnglish
Pages (from-to)821-827
Number of pages7
JournalNeuroscience
Volume81
Issue number3
DOIs
StatePublished - Sep 26 1997
Externally publishedYes

Keywords

  • Baclofen
  • Dorsal root ganglion
  • GABA-activated current
  • GABA-induced depolarization
  • Modulation
  • Whole-cell patch-clamp technique

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