Stimulus control induced by benzodiazepine antagonist Ro 15-1788 in the rat.

The imidazodiazepine Ro 15-1788 is a proposed benzodiazepine receptor antagonist. Recently however, behavioural effects of Ro 15-1788 have been demonstrated. In the present study, rats (n = 12) were trained to discriminate Ro 15-1788 (10 mg/kg, IP, t = 15 min) from vehicle in a two-lever food-reinforced procedure. All rats showed a reliable discrimination (mean injection-appropriate lever responding greater than 85%) after about 60 daily training sessions. Drug stimulus control was evidenced by an orderly generalization gradient obtained with 0.01-30 mg/kg Ro 15-1788 (ED50 for stimulus generalization: 0.12 mg/kg). Since even low doses of Ro 15-1788 have discriminative effects in the rat, it is concluded that Ro 15-1788 may have potent behavioural activity.