Roles of ginsenosides on morphine-induced hyperactivity and rewarding effect in mice

Ginsenosides, the main effective components of the root of Panax ginseng, have been reported to modulate morphine action. In the present study, ginsenosides Rd, Rb2, Rg1 and Re were divided into two groups according to their effects in mice on morphine-induced hyperactivity and conditioned place preference (CPP). Ginsenosides Rd, Rb2, Rg1 had no effect on morphine-induced hyperactivity, but antagonized morphine-induced CPP. On the contrary, ginsenoside Re increased morphine-induced hyperactivity whereas it showed no effect on morphine-induced CPP. Furthermore, Re antagonized the inhibitory effect of the mixture involving Rd, Rb2 and Rg1 on the morphine action. These results suggest that ginsenosides with different structures have antagonizing properties in the regulation of morphine-induced reinforcement.