Effect of saikosaponin A on maintenance of intravenous morphine self-administration

► Saikosaponin A dose-dependently reduced morphine self-administration. ► The effects of saikosaponin A were blocked by the GABA(B) receptor antagonist SCH 50911 but not the GABA(A) receptor antagonist bicuculline. ► Saikosaponin A did not affect food-reinforced responding. ► These results suggest that SSA may be effective in reducing the reinforcing effects of morphine.