The effect of GABA on in vitro binding of two novel non-benzodiazepines, PK 8165 and CGS 8216, to benzodiazepine receptors in the rat brain.
The effect of gamma-aminobutyric acid (GABA) on the binding of PK 8165, a quinoline derivative, and CGS 8216, a pyrazoloquinoline, was assessed in two different regions of the rat brain. PK 8165, a compound with reported anxiolytic properties, inhibited [3H]-propyl beta-carboline-3-carboxylate labeled receptors in the cerebellum with an IC50 of 844 nM and 370 nM in the absence and presence of micro M GABA, respectively. GABA (100 micro M) was less effective in the cerebral cortex, decreasing the IC50 value from 280 to 197 nM. In saturation isotherm studies with [3H]-CGS 8216, a benzodiazepine receptor antagonist, GABA (100 micro M) induced a small but significant reduction in the apparent affinity of [3H]-CGS 8216 for benzodiazepine receptors in the cerebral cortex but the Bmax was unchanged.
D000818:Animals; D000927:Anticonvulsants / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D011720:Pyrazoles / Q000378:metabolism*; D011804:Quinolines / Q000378:metabolism*; D051381:Rats; D011955:Receptors, Drug / Q000187:drug effects / Q000378:metabolism*; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D000927:Anticonvulsants; D011720:Pyrazoles; D011804:Quinolines; D011955:Receptors, Drug; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; C033830:2-phenylpyrazolo(4,3-c)quinolin-3(5H)-one; C030078:pipequaline