FLUMAZENIL ANTAGONIZES THE EFFECT OF DIAZEPAM ON NEGATIVE CONTRAST INONE-WAY AVOIDANCE-LEARNING

The main aim of the present work was to study whether the effect of di azepam upon successive negative contrast in one-way avoidance learning -induced by shifting rats from a large reward (30 s spent in the safe compartment) to a small reward (1s)-is mediated by the action of this drug on the benzodiazepine (BZ) receptor. Therefore, we studied the in fluence of flumazenil (FL), a BZ antagonist, on the effect of diazepam (DZ) on negative contrast. The i.p. administration of 5 and 12 mg/kg, but not of 2 mg/kg of FL, reliably antagonized the abolition by DZ (1 mg/kg) on successive negative contrast. Moreover, FL (12 mg/kg) did n ot affect either the avoidance response or the contrast effect. These results suggest that the GABA system is involved in the successive neg ative contrast effect in one-way avoidance learning, and that this exp erimental procedure may be useful in studies of anti-anxiety agents.