Effect of flumazenil and diazepam on transient actions in defensive burying elicited by the social interaction experience in rats

In the present work, we studied the effects of benzodiazepine (BZ) receptor antagonist, flumazenil, and of the agonist, diazepam, on social interaction-induced transient changes in defensive burying (DB). Enhanced defensive burying was observed after 1.5 min of social interaction experience, while a longer social interaction experience, 15 min, inhibited the expression of burying behavior. Defensive burying and social interaction paradigms have been used for the screening of compounds with anxiolytic potential and, more extensively, to study the neurobiology of anxiety. To elucidate the participation of the BZ receptor on transient changes induced by intervals of social interaction experience, its receptor antagonist, flumazenil (2.5, 5, and 10 mg/kg) was intraperitoneally injected (IP). Flumzenil enhanced in a dose-dependent manner, the blocking effect of the saline IP injection on facilitated DB in 1.5-min social interaction-experienced subjects. In addition, flumazenil enlarged in a dose-dependent manner the blocking effect of saline IP on defensive burying levels in animals exposed to social interaction experience for 15 min. To analyze the presumed participation of the BZ receptor mediating enhanced burying behavior levels in subjects exposed to 1.5 min of social interaction, a suboptimal dose of diazepam (0.25 mg/kg) was administered. Diazepam enhanced the saline IP elicited defensive burying reduction. Results are discussed in terms of the suggested BZ receptor mediation on transient changes in defensive burying elicited by social interaction experience. (C) 2000 Elsevier Science Inc.