Premium
Effect of chronic treatment with the GABA transaminase inhibitors γ‐vinyl GABA and ethanolamine O‐sulphate on the in vitro GABA release from rat hippocampus
Author(s) -
Qume M.,
Fowler L. J.
Publication year - 1997
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0701383
Subject(s) - gaba transaminase , chemistry , aminobutyric acid , hippocampal formation , gamma aminobutyric acid , medicine , vigabatrin , anticonvulsant , pharmacology , endocrinology , baclofen , biochemistry , biology , neuroscience , enzyme , receptor , agonist , glutamate decarboxylase , epilepsy
1 The effects of 2, 8 and 21 day oral treatment with the specific γ‐aminobutyric acid transaminase (GABA‐T) inhibitors γ‐vinyl GABA (GVG) and ethanolamine O‐sulphate (EOS) on brain GABA levels, GABA‐T activity, and basal and stimulated GABA release from rat cross‐chopped brain hippocampal slices was investigated. 2 Treatment with GABA‐T inhibitors lead to a reduction in brain GABA‐T activity by 65–80% compared with control values, with a concomitant increase in brain GABA content of 40–100%. 3 Basal hippocampal GABA release was increased to 250–450% of control levels following inhibition of GABA‐T activity. No Ca 2+ dependence was observed in either control or treated tissues. 4 GVG and EOS administration led to a significant elevation in the potassium stimulated release of GABA from cross‐chopped hippocampal slices compared with that of controls. Although stimulated GABA release from control tissues was decreased in the presence of a low Ca 2+ medium, GVG and EOS treatment abolished this Ca 2+ dependency. 5 GABA compartmentalization, Na + and Cl − coupled GABA uptake carriers and glial release may provide explanations for the loss of the Ca 2+ dependency of stimulated GABA release observed following GVG and EOS treatment. 6 Administration of GABA‐T inhibitors led to increases in both basal and stimulated hippocampal GABA release. However, it is not clear which is the most important factor in the anticonvulsant activity of these drugs, the increased GABA content ‘leaking’ out of neurones and glia leading to widespread inhibition, or the increase in stimulated GABA release which may occur following depolarization caused by an epileptic discharge.British Journal of Pharmacology (1997) 122 , 539–545; doi: 10.1038/sj.bjp.0701383