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

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