Ginseng saponins: influence on neurotransmitter uptake in rat brain synaptosomes.

The total ginsenoside ( N-butanol extract) fraction inhibited the uptake of radioactive gamma-aminobutyrate (GABA), glutamate (Glu), dopamine (DA), noradrenaline (NA), serotonin (5-HT), but not the uptake of 2-deoxy- D-glucose (2-DG) and leucine (Leu) into rat brain Synaptosomes. Among the ginsenoside fractions investigated, Fraction III which contains mainly R (d) was most effective in reducing the uptake of neurotransmitters. The inhibition was in the order of GABA = NA > DA > Glu > 5-HT, and this effect was concentration-dependent. This inhibitory effect appears to be specific as this fraction, at several concentrations, failed to influence the uptake of 2-DG and Leu significantly. Similar studies indicated that ginsenoside R (c) could affect neurotransmitter uptake specifically as well. Since the GABA uptake was most sensitive to the inhibitory action of these ginsenosides, it is postulated that ginseng may exert its action(s) in the central nervous system by affecting the removal of neurotransmitter substances in synaptic regions and that the GABA-nergic neurons may be one of the major sites of action.