Ginsenoside Rd attenuates neuroinflammation of dopaminergic cells in culture

In Parkinson's disease clinical and experimental evidence suggest that neuroinflammatory changes in cytokines caused by microglial activation contribute to neuronal death. Experimentally, neuroinflammation of dopaminergic neurons can be evoked by lipopolysaccharide (LPS) exposure. In mesencephalic primary cultures LPS (100 microg/ml) resulted in 30-50% loss of dendritic processes, changes in the perikarya, cellular atrophy and neuronal cell loss of TH-immunoreactive (TH+) cells. iNOS activity was increased dose dependently as well as prostaglandin E2 concentrations. Ginsenosides, as the active compounds responsible for ginseng action, are reported to have antioxidant and anti-inflammatory effects. Here ginsenoside Rd was used to counteract LPS neurodegeneration. Partial reduction of LPS neurotoxic action was seen in dopaminergic neurons. Cell death by LPS as well as neuroprotective action by ginsenoside Rd was not selective for dopaminergic neurons. Neuronal losses as well as cytoprotective effects were similar when counting NeuN identified neurons. The anti-inflammatory effect of ginsenoside Rd could equally be demonstrated by a reduction of NO-formation and PGE2 synthesis. Thus, protective mechanisms of ginsenoside Rd may involve interference with iNOS and COX-2 expression.