Effects of Ginseng Total Saponin on The Altered Glutamatergic Nervous Systems by AF64A in Brain of Rats

To investigate effects of ginseng total saponin (GTS) on the ethylcholine aziridnium ion (AF64A) -induced glutamatergic nervous system, rats were pretreated with the infusion of AF64A (3 nmole) into lateral ventricle and were posttreated with 50 mg/kg of GTS, i.p., for 1 week. Twenty four hours after the last administration, rats were sacrificed and the levels of glutamate and taurine, [$^3$H]dizocilpine ([$^3$H]MK801) binding sites and glutamine synthetase activity were assessed in striatum, hippocampus and frontal cortex. The levels of striatal glutamate after GTS treatment in rats were decreased. And the levels of glutamate were decreased in striatum and frontal cortex and increased in hippocampus by the infusion of AF64A. However, the AF64A-induced changes of glutamate were returned to the control level by the administration of GTS in striatum, frontal cortex and hippocampus. After the infusion of AF64A, the level of taurine was decreased in striatum and increased in hippocampus. GTS administrations in the AF64A-treated rats restored to the control level of taurine in the decreased striatal level of taurine, but not in the elevated level of hippocampal taurine. The specific [$^3$H]MK801 binding sites in hippocampus was significantly decreased but not in striatum and frontal cortex after the administration of AF64A. Although GTS itself did not affect the specific [$^3$H]MK801 binding sites, GTS administrations in the AF64A-treated rats did decrease the binding sites of (\`H)Mk801 in all examined regions. The activities of striatal glutamine synthetase were decreased after GTS treatment. The activities of striatal glutamine synthetase (GS) were decreased in AF64A-treated groups. However, the decreased striatal GS activities by AF64A were returned to the control level by GTS treatment. Furthermore, GTS administrations in the AF64A-treated rats increased the hippocampal GS activities. The results indicatethat GTS may adjust the levels of glutamate and taurine constantly and may induce increase in AF64A-induced decrease of GS activity. Thus, it suggests that GTS may antagonize changes in central glutamatergic nervous system induced by AF64A. Also it suggests that the actions of GTS may differently affect in the disease state.