Reversal of chlordiazepoxide‐induced impairment in successive discrimination performance by RO 15‐1788

Abstract

AbstractThe effects of chiordiazepoxide (CDP) alone and in combination with Ro 15‐1788 on the performance of a previously learned go‐no go successive discrimination were studied in male Sprague‐Dawley rats. CDP 10 mg/kg impaired discrimination performance in six sucessive sessions, with animals showing recovery in two post‐drug sessions. The impairment in disrcimination performance was due to an increase in responding during no go (waiting) periods of the task. The benzodizepine (BDZ) receptor antagonist Ro 15‐778 (5 and 10 mg/kg) reversed the impairment in discrimination performance in sessions 2‐6 (but not 1) when co‐administered with CDP. While the effectiveness of Ro 15‐1788 was not dose‐dependent, the reversal in discrimination impairment was due to a reduction in responding during no go periods of the task. These findings suggest that the impairment in discrimination performance produced by CDP is mediated by central BDZ receptor sites. When administered alone, Ro 15‐1788 10 mg/kg (but not 5mg/kg) produced a mild BDZ‐like impairment in discrimination performance and increase in a no go period responding. These findings suggest that Ro 15‐1788 is not a neutral antagonist but has some intrinsic action of its own.