Acute and chronic effects of ginseng total saponin and amphetamine on fixed-interval performance in rats

The effect of ginseng total saponin (GTS) on amphetamine (AMPH)-induced dis ruption of fixed-interval (FI) responding in rats was examined. GTS (50 mg/ kg) significantly improved the temporal responding impaired by 2 mg/kg of A MPH. A higher dose of 100 mg/kg CTS disrupted performance when given alone; this disruption was reversed by a low dose of AMPH (0.5 mg/kg) and toleran ce developed to the effects of GTS with its repeated administration. Neuroc hemical analysis revealed that GTS (50 mg/kg) attenuated the increase in st riatal dopamine caused by AMPH leading to the conclusion that brain dopamin e may partially mediate the behavioral effects of GTS.