Endogenous GABA release from rat striatal slices: Effects of the GABAB receptor antagonist 2‐hydroxy‐saclofen
- 1 May 1993
- Vol. 14 (1), 16-23
- https://doi.org/10.1002/syn.890140104
Abstract
The reproducibility of endogenous GABA release evoked by multiple periods of electrical field stimulation was examined in rat striatal slices. In these experiments, NO‐328 was used to block GABA uptake, and evoked GABA release (overflow) was completely Ca2+ dependent. A seemingly invariant observation in these experiments was that spontaneous GABA release (outflow) progressively decreased as a function of superfusion time and that GABA overflow decreased 25–30% in response to the second of two periods of stimulation (S2/S1 ratios = 0.70 to 0.75). The attenuation of GABA release was not explained by the amount of GABA lost to the superfusion buffer (fractional release), direct depletion of releasable pools of GABA, or slice viability. Furthermore, the decreases in GABA release were not dependent on stimulation frequency (5–15 Hz) or the absolute amount of GABA evoked by electrical stimulation. However, the GABAB receptor antagonist 2‐hydroxy‐saclofen (2‐OH‐saclofen; 316 μM) not only enhanced GABA overflow, when superfused throughout both periods of stimulation, but also resulted in S2/S1 ratios of unity. When 2‐OH‐saclofen was superfused throughout the second stimulation period only, GABA overflow was almost two‐fold greater than that evoked by the initial period of stimulation (2‐OH‐saclofen‐free). In addition, these S2 responses were ∼30% greater than S1 responses that were observed when 2‐OH‐saclofen was present throughout the entire superfusion period. These results indicate that activation of GABAB receptors was involved in the progressive attenuation of GABA release and further emphasize that GABAB receptors play an important role in modulating endogenous GABA release from striatal slices. © Wiley‐Liss, Inc.This publication has 30 references indexed in Scilit:
- The neostriatal mosaic: multiple levels of compartmental organizationTrends in Neurosciences, 1992
- GABAB autoreceptors regulate the induction of LTPNature, 1991
- The actions of 2-hydroxy-saclofen at presynaptic GABAB receptors in the rat hippocampusNeuroscience Letters, 1990
- GABA transaminase inhibitors enhance the release of endogenous GABA but decrease the release of β-alanine evoked by electrical stimulation of slices of the rat medulla oblongataLife Sciences, 1988
- INTRODUCTIONActa Neurologica Scandinavica, 1986
- Stress‐Induced Enhancement of Suppression of [3H]GABA Release from Striatal Slices by Presynaptic AutoreceptorJournal of Neurochemistry, 1984
- Compartments of Labeled and Endogenous γ‐Aminobutyric Acid Giving Rise to Release Evoked by Potassium or Veratridine in Rat Cortical SlicesJournal of Neurochemistry, 1981
- Electrophysiological interactions of enkephalins with neuronal circuitry in the rat hippocampus. I. Effects on pyramidal cell activityBrain Research, 1980
- UPTAKE AND RELEASE OF NIPECOTIC ACID BY RAT BRAIN SLICESJournal of Neurochemistry, 1976
- Multiple Comparisons among MeansJournal of the American Statistical Association, 1961