Effect of rhynchophylline on central neurotransmitter levels in amphetamine-induced conditioned place preference rat...

The effects of rhynchophylline on expression of amphetamine reward using a conditioned place preference (CPP) paradigm and central neurotransmitter levels in rat brain was investigated. Rats were injected with amphetamine (2 mg/kg, per day for 4 consecutive days) and treated with rhynchophylline (60 mg/kg, per day for the later 3 days). Control rats were administered with rhynchophylline (60 mg/kg) instead of amphetamine to evaluate whether rhynchophylline by itself produced CPP. Glutamic acid, γ-aminobutyric acid, endorphin, acetylcholine, norepinephrine, dopamine, and 5-hydroxytryptamine contents were examined by encephalofluogram technology. Rhynchophylline reversed the expression of amphetamine-induced CPP and itself did not produce a CPP. Glutamic acid, dopamine, and norepinephrine contents in amphetamine-CPP rat brain were significantly higher; while γ-aminobutyric acid, endorphin, and acetylcholine contents were significantly lower than those of control rats. Rhynchophylline reversed those central neurotransmitter levels induced by amphetamine to control levels; rhynchophylline by itself had no effect on central neurotransmitter in control rats. These findings show that rhynchophylline reverses the expression of amphetamine-induced rewarding effect which is partly mediated by regulation of central neurotransmitter levels in the rat brain.