Effects of saikosaponin A on cocaine self-administration in rats.

We have previously demonstrated that saikosaponin A (SSA) attenuated morphine self-administration behavior. In the present study, we evaluated the effects of SSA on cocaine-maintained responding using self-administration procedure. Rats self-administered cocaine (0.25mg/kg per infusion) under a fixed ratio 1 schedule of reinforcement during daily 3-h session. Once stable basal responses were obtained, rats were pretreated with each doses of SSA (1.0, 2.5, 5.0mg/kg) or its vehicle (5% Tween-80) by an intraperitoneal injection 30min before the start of self-administration testing. Additionally, different groups of rats received either the selective GABAB antagonist SCH 50911 or the GABAA antagonist bicuculline before systemic administration of SSA at dose of 2.5mg/kg. Results showed that SSA significantly reduced cocaine self-administration without affecting food consumption. SSA inhibition of cocaine reinforced-responding was blocked by SCH 50911, but not bicuculline. Results suggest that SSA may attenuate cocaine-reinforced behavior through activation of GABAB receptors.