Improvement of memory in mice and increase of hippocampal excitability in rats by ginsenoside Rg1′s metabolites ginsenoside Rh1 and protopanaxatriol

The aim of present study is to observe the effect of ginsenoside Rg1′s metabolites(primary metabolit ginsenoside Rh1 and end metabolite protopanaxatriol) on learning and memory function.we employed the step through test and electrophysiological study to investigate the effects of Rh1 and Ppt on learning and memory as well as hippocampal excitability.The behavioral study showed that both ginsenoside Rh1 and Ppt significantly ameliorated memory-impaired model induced by scopolamine in mice.Consistently,electrophysiological work revealed that Rh1 and Ppt as well as their precursor Rg1 all increased hippocampal excitability in the dentate gyrus of anesthetized rats.The metabolism of Rg1 in cerebrospinal fluid was detected by HPLC-MS,indicating that Rg1 could not convert into Rh1 or Ppt.These results demonstrated that both Rh1 and Ppt have similar effect on improving memory and hippocampal excitability,suggesting that the role of ginsenoside’s sugar moeties in biological activities is not as necessary as traditionally considered.