Effect of Panax ginseng on age-related changes in the spontaneous motor activity and dopaminergic nervous system in the rat.

Effects of Panax ginseng on the spontaneous motor activity and central dopaminergic systems in old rats were investigated and compared with those in young rats. Oral intake of a 1.8% water extract of Panax ginseng for four weeks produced an increase in spontaneous motor activity during the dark period in old rats, while it caused a decrease in the activity in young rats. After the intake of ginseng extract for five weeks, it caused a significantly low dopamine utilization in the daytime in the striatum of old rats, while it produced a high dopamine utilization in the structure of young rats. Concentrations of striatal dopamine D-2 receptors in old rats were significantly lower than that in young rats, although subchronic Panax ginseng did not affect the striatal D-1 and D-2 receptors of old rats. These results suggest that subchronic intake of ginseng extract inhibits the activity of nigro-striatal dopamine neurons in the daytime and activates spontaneous motor activity during the dark period in old rats, while it produces opposite effects in young rats.