Synaptically released GABA activates both pre- and postsynaptic GABA B receptors in the rat globus pallidus

Katsuyuki Kaneda, Hitoshi Kita

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

The globus pallidus (GP) contains abundant GABAergic synapses and GABA B receptors. To investigate whether synaptically released GABA can activate pre- and postsynaptic GABAB receptors in the GP, physiological recordings were performed using rat brain slice preparations. Cell-attached recordings from GABAA antagonist-treated preparations revealed that repetitive local stimulation induced a GABAB antagonist-sensitive pause in spontaneous firings of GP neurons. Whole cell recordings revealed that the repetitive stimulation evoked fast excitatory postsynaptic potentials followed by a slow inhibitory postsynaptic potential (IPSP) in GP neurons. The slow IPSP was insensitive to a GABAA receptor antagonist, increased in amplitude with the application of ionotropic glutamate receptor antagonists, and was suppressed by the GABAB antagonist CGP55845. The reversal potential of the slow IPSP was close to the potassium equilibrium potential. These results suggest that synaptically released GABA activated postsynaptic GABAB receptors and induced the pause and the slow IPSP. On the other hand, in the neurons that were treated to block postsynaptic GABAB responses, CGP55845 increased the amplitudes of repetitive local stimulation-induced GABAA-mediated inhibitory postsynaptic currents (IPSCs) but not the ionotropic glutamate-mediated excitatory postsynaptic currents. Moreover, the GABAB receptor specific agonist baclofen reduced the frequency of miniature IPSCs without altering their amplitude distributions. These results suggest that synaptically released GABA also activated presynaptic GABAB autoreceptors, resulting in decreased GABA release in the GP. Together, we infer that both pre- and postsynaptic GABAB receptors may play crucial roles in the control of GP neuronal activity.

Original languageEnglish (US)
Pages (from-to)1104-1114
Number of pages11
JournalJournal of Neurophysiology
Volume94
Issue number2
DOIs
StatePublished - Aug 1 2005

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GABA-B Receptors
Inhibitory Postsynaptic Potentials
Globus Pallidus
gamma-Aminobutyric Acid
GABA-A Receptor Antagonists
Excitatory Postsynaptic Potentials
Neurons
Ionotropic Glutamate Receptors
Autoreceptors
Excitatory Amino Acid Antagonists
Baclofen
Patch-Clamp Techniques
Synapses
Glutamic Acid
Potassium
Brain

All Science Journal Classification (ASJC) codes

  • Physiology
  • Neuroscience(all)

Cite this

Synaptically released GABA activates both pre- and postsynaptic GABA B receptors in the rat globus pallidus. / Kaneda, Katsuyuki; Kita, Hitoshi.

In: Journal of Neurophysiology, Vol. 94, No. 2, 01.08.2005, p. 1104-1114.

Research output: Contribution to journalArticle

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