6-Methyl-3'-bromoflavone, a high affinity ligand for the benzodiazepine binding site of the GABAA receptor with some agonistic properties.

H. VIOLA; M. MARDER; J. NUÑEZ; L. IZQUIERDO; C. WASOWSKI; C. WOLFMAN; P. ARDENGHI; D. BARROS; J. H. MEDINA; A. C. PALADINI

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS

Año: 1999 vol. 262 p. 643 - 646

0006-291X

6-Methyl-3*-bromoflavone inhibited [3H]flunitrazepam binding to the benzodiazepine binding site of the GABAA receptor (BDZ-bs) with Ki values between 10 and 50 nM in different brain regions.The GABA ratio of 1.03 for [3H]flunitrazepam binding to cerebral cortex, 0.76 for cerebellum, 0.7 for hippocampus, 0.7 for striatum, and 0.8 for spinal cord indicated an antagonistic or weak inverse agonistic profile of 6-methyl-3*-bromoflavone on BDZ-bs. Unlike classical benzodiazepines, it had no anticonvulsant, anxiolytic, myorelaxant, sedative, amnestic or motor incoordination effects. However, it antagonized the muscle relaxant, the sedative effect, and the changes in locomotor activity induced by diazepam. Taken together, these findings suggest that 6-methyl-3*-bromoflavone has an antagonistic profile on the BDZ-bs.*-bromoflavone inhibited [3H]flunitrazepam binding to the benzodiazepine binding site of the GABAA receptor (BDZ-bs) with Ki values between 10 and 50 nM in different brain regions.The GABA ratio of 1.03 for [3H]flunitrazepam binding to cerebral cortex, 0.76 for cerebellum, 0.7 for hippocampus, 0.7 for striatum, and 0.8 for spinal cord indicated an antagonistic or weak inverse agonistic profile of 6-methyl-3*-bromoflavone on BDZ-bs. Unlike classical benzodiazepines, it had no anticonvulsant, anxiolytic, myorelaxant, sedative, amnestic or motor incoordination effects. However, it antagonized the muscle relaxant, the sedative effect, and the changes in locomotor activity induced by diazepam. Taken together, these findings suggest that 6-methyl-3*-bromoflavone has an antagonistic profile on the BDZ-bs.