IN-VIVO MODULATION OF BENZODIAZEPINE RECEPTOR FUNCTION AFTER INHIBITION OF ENDOGENOUS GAMMA-AMINOBUTYRIC-ACID SYNTHESIS

The influence of decreased endogenous gamma-aminobutyric acid (GABA) c oncentration on benzodiazepine receptor function was studied in the br ain of living baboons. Positron emission tomography and the radiotrace r [C-11]flumazenil combined with electroencephalography were used to d etermine the pharmacological properties of two benzodiazepine receptor s agonists, diazepam and bretazenil, in baboons pre-treated or not wit h DL-allylglycine (an inhibitor of GABA synthesis). Our results show t hat, in vivo, DL-allylglycine reduces the affinity of benzodiazepine r eceptors for their agonists without altering the intrinsic capability of agonists to allosterically modulate GABAergic transmission. (C) 199 7 Elsevier Science B.V.