Actions of ginsenoside Rb1 on choline uptake in central cholinergic nerve endings

The ginsenoside Rb1 has previously been reported to improve memory deficits induced by anticholinergic drug treatment, and to facilitate acetylcholine (Ach) release from rat brain hippocampal slices. The increase in ACh release was not associated with an increase in calcium uptake into nerve terminals, but was associated with an increase in uptake of the precursor choline. In the present studies, analysis of choline uptake kinetics indicated that Rb1 increased the maximum velocity of choline uptake, while the affinity of the choline uptake carrier for choline (Km) was not significantly altered. Acute treatment with Rb1 did not alter the number of [3H]hemicholinium-3 (HC-3) binding sites in any of three cholinergic brain regions examined, suggesting that the increase in the maximum velocity of choline uptake was not associated with an increase in the number of choline carriers. However, chronic (3 day) administration of Rb1 did increase the number of choline uptake sites in the hippocampus, and to a lesser extent in the cortex.