Diazepam selectively biases approach during threat–reward conflict while sparing reactive avoidance

Rationale: Benzodiazepines are widely used to treat anxiety; however, their influence on defensive behavior when threats compete with rewards remains unclear. Objectives Here, we tested the effects of diazepam on reactive avoidance (no conflict), threat–reward conflict resolution, and behavioral flexibility. Methods Using an integrated platform-mediated avoidance paradigm in female and male rats, we assessed the effects of a low dose systemically administered diazepam (1 mg/kg). Results Diazepam did not alter the reactive avoidance memory expression when threat cues were presented without a concurrent reward cue. In contrast, during the cued threat–reward conflict, diazepam reduced platform avoidance and increased reward engagement, shifting the avoidance/approach balance toward the approach. Diazepam also impaired behavioral flexibility during the reversal from conflict to reactive avoidance, maintaining an approach-dominant strategy when avoidance should be reinstated. Sex differences were observed selectively during the flexibility assessment, reflecting a quantitatively stronger diazepam-induced shift toward reward engagement in males compared with females. Control assays showed no significant effects of diazepam on threat or reward memory retrieval, sucrose intake, open-field locomotion, or anxiety-like behavior. Conclusions These findings indicate that diazepam selectively reshapes approach–avoidance arbitration under motivational competition and alters subsequent flexibility while sparing reactive avoidance.