Pharmacological and physiological effects of ginseng on actions induced by opioids and psychostimulants.

Pharmacological and physiological effects of ginseng on actions induced by opioids and psychostimulants are summarized. Analgesic effects of opioids, such as morphine and U-50, 488H, were blocked by ginseng in a nonopioid dependent manner. Furthermore, ginseng inhibited the tolerance to and dependence on morphine, and eliminated the suppressive effect of the development of morphine tolerance by coexposure to footshock stress, but not psychological stress. On the other hand, behavior sensitization (reverse tolerance to their ambulation-accelerating effect) to morphine, methamphetamine and cocaine was also inhibited by ginseng. Interestingly, ginseng also inhibited the appearance of the recurrent phenomenon (reappearance of the sensitized state was observed at the time of readministration of methamphetamine and cocaine even after a 30-day discontinuation of drug administration) of the effect of methamphetamine and cocaine. The conditioned place preference of methamphetamine and cocaine was completely blocked by ginseng. These findings provide evidence that ginseng may be useful clinically for the prevention of abuse and dependence of opioids and psychostimulants.