Neurotrophic and neuroprotective actions of ginsenosides Rb-1 and Rg(1)

The ginsenosides have many pharmacological actions, including various actio ns on the nervous system. Our previous studies have demonstrated that two g insenosides, Rb-1 and Rg(1) improve performance in a passive avoidance-lear ning paradigm and enhance cholinergic metabolism. The present study was des igned to examine the cellular neurotrophic and neuroprotective actions of t wo pure ginsenosides in two model systems. PC12 cells were grown in the abs ence or presence of nerve growth factor (NGF) as a positive control, and di fferent concentrations of Rb-1 or Rg(1). To assess neurotrophic properties, neurite outgrowth was quantified for representative fields of cells. After 8 days in culture, both ginsenosides enhanced neurite outgrowth in the pre sence of a sub-optimal dose of (2 ng/ ml) NGF, but did not significantly st imulate neurite outgrowth in the absence of NGF. However, after 18 days in culture, both ginsenosides increased neurite outgrowth in the absence of NG F. SN-K-SH cells were grown in the absence or presence of MPTP or beta -amy loid to assess neuroprotection. Rb-1 and Rg(1) both reversed MPTP-induced c ell death. beta -Amyloid-induced cell death was not reversed by either gins enoside, but Rg(1) produced a modest enhancement of cell death in this mode l. These results suggest that these two ginsenosides have neurotrophic and selective neuroprotective actions that may contribute to the purported enha ncement of cognitive function.