THE BENZODIAZEPINE RECEPTOR ANTAGONISTS FLUMAZENIL AND CGS8216 BLOCK THE ENHANCEMENT OF FEAR CONDITIONING AND INTERFERENCE WITH ESCAPE BEHAVIOR PRODUCED BY INESCAPABLE SHOCK

Prior work has suggested that the mediation of the behavioral effects of inescapable shock (IS) might involve release of an endogenous beta- carboline-like ligand at the dorsal raphe nucleus (DRN) that binds to the benzodiazepine (BZ) recognition site on the GABA(A) complex, there by disinhibiting the DRN. This was tested by microinjection of the BZ receptor antagonists flumazenil and CGS8216 in the region of the DRN, either before IS or before later behavioral testing. Both compounds bl ocked subsequent enhancement of fear conditioning and interference wit h shuttlebox escape when administered before IS, but had no effect whe n given before testing, In addition, flumazenil did not alter the beha vior of escapably shocked subjects.