Effects of GABA antagonists, SR 95531 and bicuculline, on GABAA receptor-regulated chloride flux in rat cortical synaptoneurosomes

1990 ◽  
Vol 15 (9) ◽  
pp. 905-910 ◽  
Author(s):  
Sue Yu ◽  
I. K. Ho
Keyword(s):  
Gabaa Receptor ◽  
Chloride Flux ◽  
Gaba Antagonists ◽  
Sr 95531

Contributions of GABAA receptors and GABAC receptors to acetylcholine release and directional selectivity in the rabbit retina

1997 ◽  
Vol 14 (5) ◽  
pp. 939-948 ◽  
Author(s):  
Stephen C. Massey ◽  
David M. Linn ◽  
Christopher A. Kittila ◽  
Wajid Mirza
Keyword(s):  
Ganglion Cells ◽  
Bipolar Cells ◽  
High Dose ◽  
Directional Selectivity ◽  
Ach Release ◽  
Gaba Antagonists ◽  
Inhibitory Neurotransmitter ◽  
Postsynaptic Receptors ◽  
Release Of Acetylcholine ◽  
Sr 95531

AbstractGABA is a major inhibitory neurotransmitter in the mammalian retina and it acts at many different sites via a variety of postsynaptic receptors. These include GABAA receptors and bicuculline-resistant GABAC receptors. The release of acetylcholine (ACh) is inhibited by GABA and strongly potentiated by GABA antagonists. In addition, GABA appears to mediate the null inhibition which is responsible for the mechanism of directional selectivity in certain ganglion cells. We have used these two well-known examples of GABA inhibition to compare three GABA antagonists and assess the contributions of GABAA and GABAC receptors. All three GABA antagonists stimulated ACh release by as much as ten-fold. By this measure, the ED50s for SR-95531, bicuculline, and picrotoxin were 0.8, 7.0, and 14 μM, respectively. Muscimol, a potent GABAA agonist, blocked the effects of SR-95531 and bicuculline, but not picrotoxin. This indicates that SR-95531 and bicuculline are competitive antagonists at the GABAA receptor, while picrotoxin blocks GABAA responses by acting at a different, nonreceptor site such as the chloride channel. In the presence of a saturating dose of SR-95531 to completely block GABAA receptors, picrotoxin caused a further increase in the release of ACh. This indicates that picrotoxin potentiates ACh release by a mechanism in addition to the block of GABAA responses, possibly by also blocking GABAC receptors, which have been associated with bipolar cells. All three GABA antagonists abolished directionally selective responses from ON/OFF directional-selective (DS) ganglion cells. In this system, the ED50s for SR-95531, bicuculline, and picrotoxin were 0.7 μM, 8 μM, and 94.6 μM, respectively. The results with SR-95531 and bicuculline indicate that GABAA receptors mediate the inhibition responsible for directional selectivity. The addition of picrotoxin to a high dose of SR-95531 caused no further increase in firing rate. The comparatively high dose required for picrotoxin also suggests that GABAC receptors do not contribute to directional selectivity. This in turn suggests that feedforward GABAA inhibition, as opposed to feedback at bipolar terminals, is responsible for the null inhibition underlying directional selectivity.

Synthesis and evaluation of highly potent GABAA receptor antagonists based on gabazine (SR-95531)

2011 ◽  
Vol 21 (14) ◽  
pp. 4252-4254 ◽  
Author(s):  
Favaad Iqbal ◽  
Ryan Ellwood ◽  
Martin Mortensen ◽  
Trevor G. Smart ◽  
James R. Baker
Keyword(s):  
Gabaa Receptor ◽  
Receptor Antagonists ◽  
Sr 95531

Zinc modulation of GABAA receptor-mediated chloride flux in rat hippocampal slices

1995 ◽  
Vol 691 (1-2) ◽  
pp. 125-132 ◽  
Author(s):  
Marina Gordey ◽  
Maenghee Kang ◽  
Richard W. Olsen ◽  
Igor Spigelman
Keyword(s):  
Gabaa Receptor ◽  
Hippocampal Slices ◽  
Chloride Flux

ChemInform Abstract: Synthesis and Evaluation of Highly Potent GABAA Receptor Antagonists Based on Gabazine (SR-95531).

ChemInform ◽  
2011 ◽  
Vol 42 (48) ◽  
pp. no-no
Author(s):  
Favaad Iqbal ◽  
Ryan Ellwood ◽  
Martin Mortensen ◽  
Trevor G. Smart ◽  
James R. Baker
Keyword(s):  
Gabaa Receptor ◽  
Receptor Antagonists ◽  
Sr 95531

259: Melatonin Enlarges the Bladder by the Gabaa Receptor in the Brain, Suggesting its Efficaciousness Against Nocturia

2007 ◽  
Vol 177 (4S) ◽  
pp. 86-87
Author(s):  
Yosuke Matsuta ◽  
Aniwar Yusup ◽  
Masaharu Nakai ◽  
Kazuya Tanase ◽  
Yoshitaka Aoki ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
The Brain

Cinnamamides from Piper capense with affinity to the benzodiazepine site on the GABAA receptor

Planta Medica ◽  
2008 ◽  
Vol 74 (09) ◽  
Author(s):  
ME Pedersen ◽  
HB Rasmussen ◽  
B Metzler ◽  
GI Stafford ◽  
J van Staden ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
Benzodiazepine Site
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