[(35)S]TBPS binding to purified benzodiazepine-GABA-ionophore receptor complex: the effect of GABA on the modulation exerted by benzodiazepine site ligands.
Benzodiazepine GABA-ionophore receptor complex ligands showed persistent modulation of the chloride ionophore, labeled by [(35)S]TBPS, even after receptor complex extensive purification. GABA caused inhibition of [(35)S]TBPS binding, while benzodiazepine agonists increased and benzodiazepine inverse agonists decreased the specific [(35)S]TBPS binding to the purified receptor. When GABA binding sites were occupied by the neurotransmitter benzodiazepine receptor agonists and antagonists reversed their effects clonazepam in fact inhibited and ?-carboline ethyl ester increased [(35)S]TBPS binding in the presence of GABA. The antagonist flumazenil showed no effect both in the presence or absence of GABA.
Martini
C
C
Istituto di Chimica Biologica, Universita' di Parma, 43100 Parma, Italy; Istituto Policattedra di Discipline Biologiche, Universita' di Pisa, 56100 Pisa, Italy.
Pacini
R
R
Giannaccini
G
G
Lucacchini
A
A