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γ‐Aminobutyric Acid and Pentobarbital Enhance 2‐[ 3 H]Oxoquazepam Binding to Type I Benzodiazepine Recognition Sites in Rat and Human Brain
Author(s) -
Corda M. G.,
Giorgi O.,
Longoni B.,
Ongini E.,
Barnett A.,
Montaldo S.,
Biggio G.
Publication year - 1988
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1988.tb02967.x
Subject(s) - pentobarbital , flunitrazepam , chemistry , aminobutyric acid , benzodiazepine , binding site , cerebellum , pharmacology , cerebral cortex , biochemistry , biophysics , medicine , endocrinology , receptor , biology
2‐Oxoquazepam (2oxoquaz) is a novel benzodiazepine which shows preferential affinity for type I benzodiazepine recognition sites. In the present study, we analyzed the effect of γ‐aminobutyric acid (GABA), pentobarbital, and chloride ions on [ 3 H]2oxoquaz and [ 3 H]flunitrazepam ([ 3 H]FNT) binding to membrane preparations from rat and human brain. GABA stimulated [ 3 H]‐2oxoquaz and [ 3 H]FNT binding in a concentration‐dependent manner. The maximal enhancement produced by GABA on [ 3 H]2oxoquaz binding was higher than that produced on [ 3 H]FNT binding in both rat and human tissues. In the rat brain, the effect of GABA on [ 3 H]2oxoquaz was similar throughout different brain areas, whereas the effect on [ 3 H]FNT binding was lower in the cerebral cortex and hippocampus than in the cerebellum. Moreover, both [ 3 H]2oxoquaz and [ 3 H]FNT binding were stimulated by chloride ions and pentobarbital. The results are consistent with the hypothesis that type I benzodiazepine recognition sites are linked functionally to the GABA recognition site and the chloride ionophore.