Preliminary study on antiamnestic mechanism of ginsenoside Rg1 and Rb1.

The effect of ginsenoside Rg1 and Rb1 on memory in mice and rats were studied using one trial avoidance learning method. The results showed that Rg1 and Rb1 improved acquisition, consolidation and retrieval of memory improved by amnestic agents. For the elucidation of the antiamnestic mechanism of Rg1 and Rb1, HPLC-ECD, isotope labelling technique, radioligand binding assay, RIA and oxygen radical generating systems were employed in experiments. Rg1 and Rb1 were shown to increase protein bisynthesis of brain and ACTH level of plasma and decrease 5-HT level or slow down the 5-HT turnover rate in rats. No specific binding of Rg1 and Rb1 to alpha 1, alpha 2 and beta-adrenoceptors, or to DA, 5-HT, GABA and M-cholinergic receptors was detectable. However, 5 days after ip Rg1 and Rb1, higher Bmas values were obtained for the brain membranes from treated mice than those from control mice. In the mean time, Rg1 and Rb1 did not lower and might even increase the contents of acetylcholine in the brain. Besides, Rb1 could antagonize lipid peroxidation in the brain. Besides, Rb1 could antagonize lipid peroxidation and scavenge oxygen free radicals as well as increase catalase and GSH-PX activities. Clearly, these data may serve as the basis for the elucidation of the antiamnestic mechanism of Rg1 and Rb1.