Effects of ginseng saponins on beta-amyloid-induced amnesia in rats.
We have previously demonstrated that ginseng saponins (GS) can reverse the inhibitory effect of beta-amyloid on acetylcholine (ACh) release in the hippocampal slices. The present study was carried out to examine whether GS has any beneficial effects against amnesia induced by beta-amyloid peptides in vivo. Intracerebroventricular injection of 50 microg, but not 10 microg, beta-amyloid fragment(25-35) markedly impaired the performance of rats in avoiding a shock prod, confirming the amnesiac effect of beta-amyloid. Chronically treating the rats with GS (orally, 5 days before icv beta-amyloid injection and 7 days afterward) resulted in a dose-related improvement against beta-amyloid-induced amnesia; a significant reversion was observed at the highest GS dose (80 mg/kg/day). Post-treatment analysis on K(+)-evoked [(3)H]-ACh release from the hippocampal slices showed that beta-amyloid-treatment significantly reduced ACh release from that of the control group. However, pre-treatment with GS completely protected the animal against beta-amyloid-induced reduction of hippocampal ACh release. In contrast, treating the animals with the same optimal dose of GS and duration but only after icv beta-amyloid injection was found to be ineffective in obliterating beta-amyloid's amnesiac effect. Taken together, these observations indicated that GS pre-treatment can functionally prevent the beta-amyloid-induced memory loss possibly by minimizing the inhibitory effect of beta-amyloid on hippocampal cholinergic transmission.
Wang
Lawrence C H
LC
Department of Biological Sciences, Biological Science Bldg., University of Alberta, Edmonton, Alta., Canada. larry.wang@ualberta.ca
Wang
Beatrice
B
Ng
Sum-Yan
SY
Lee
Tze-Fun
TF
D000109:Acetylcholine / Q000378:metabolism; D000647:Amnesia / Q000188:drug therapy*; D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D005625:Frontal Lobe / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D005894:Panax / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012503:Saponins / Q000627:therapeutic use*
D016229:Amyloid beta-Peptides; D012503:Saponins; D000109:Acetylcholine