Ginsenoside Rg3 Attenuates Microglia Activation Following Systemic Lipopolysaccharide Treatment in Mice

Neuroinflammation, characterized by activation of microglia and expression of major inflammatory mediators, contributes to neuronal damage in addition to acute and chronic central nervous system (CNS) disease progression. The present study investigated the immune modulatory effects of ginsenoside Rg(3), a principle active ingredient in Panax ginseng, on pro-inflammatory cytokines and microglia activation in brain tissue induced by systemic lipopolysaccharide (LPS) treatment in C57BL/6 mice. Systemic LPS treatment induces immediate microglia activation in the brain. Based on this information, ginsenoside Rg(3) was treated orally with 10, 20, and 30 mg/kg 1 h prior to the LPS (3 mg/kg, intraperitoneally (i.p.)) injection. Ginsenoside Rg(3) at 20 and 30 mg/kg oral doses significantly attenuated up-regulation of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and IL-6 mRNA in brain tissue at 4 h after LPS injection. Morphological activation of microglia and Iba1 protein expression by systemic LPS injection were reduced with ginsenoside Rg(3) (30 mg/kg) treatment. In addition, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in brain tissue were also attenuated with oral treatment of ginsenoside Rg(3) at 30 mg/kg. These results indicate that ginsenoside Rg(3) plays a modulatory role in neuroinflammation. This study shows that ginsenoside Rg(3) attenuates microglia activation using an in vivo animal model.