Experimental Study Of The Abti-inflammatory Effect Of Ginsenoside Rg1 Via Glucocorticoid Receptor,Insulin-like Growth Factor-â…  Receptor And Estrogen Receptor In BV-2 Microglial Cells

Ginsenoside Rg1 is the major pharmacological ingredient of traditional Chinese herbal medcine ginseng. Studies have shown that Rg1 possess a variety of beneficial effects on human health, including anti-inflammation, antioxidant, anti-neurotoxin. Microglia is one of the immune cells of the nervous system. Over-activated microglia could induce neuronal injury or neuronal death by producing cytokines and proinflammatory enzymes. So microglial cells play a very important role in onset and progression of neurodegenerative diseases. Accumulating experimental evidence shows that the Rg1 has anti-inflammatory function, but the detail molecular mechanism is not very clear until now. Studies have shown that Rg1, a functional ligand of glucocoticoid receptor(GR), possesses steroid skeleton structure. Our previous work has demonstrated that ginsenoside Rg1 has estrogen-like activity. Rg1 could protect dopaminergic neurons from the neurotoxin-induced neuronal injury through the esgrogen receptor(ER) and insulin-1ike growth factor-Ⅰ receptor(IGF-ⅠR) signaling pathways. However, no data indicate that GR, ER and IGF-ⅠR are related to the anti-inflammatory effects of Rg1 in BV-2 microglial cells. The present study aimed to evaluate the protective effects of Rg1 on lipopolysaccharide(LPS)-induced BV-2 microglial activation and the potential mechanism. The experimental methods include immunofluorescence, real-time PCR and western blot. Results are as follows:1. LPS significantly increased the gene and protein expressions of proinflammatory cytokines in BV-2 microglial cells(P<0.05). Ginsenoside Rg1(10μM) could inhibit LPS-induced inflammation(P<0.05).2. The inhibitory effect of ginsenoside Rg1 on LPS-induced gene expressions of i NOS, COX-2, IL-1β and TNFα could not be blocked by GR antagonist RU486(1μM) in BV-2 microglial cells(P >0.05).3. ER antagonist ICI182,780(1μM) could block the inhibitory effect of ginsenoside Rg1 on LPS-induced gene expressions of i NOS, COX-2, IL-1β and TNFα in BV-2 microglial cells(P<0.05).4. IGF-ⅠR antagonist JB-1(1μM) could block the inhibitory effect of ginsenoside Rg1 on LPS-induced gene expressions of i NOS, COX-2, IL-1β and TNFα in BV-2 microglial cells(P<0.05).5. RU486 or JB-1 could block the inhibitory effect of ginsenoside Rg1 on LPS-induced protein expressions of i NOS and COX-2 in BV-2 microglial cells(P<0.05). ICI182,780 could partly block the inhibitory effect of Rg1.6. LPS could significantly increase the phosphorylation levels of MAPKs(ERK, JNK, p38). Pre-treatment with Rg1 could protect against the protein phosphorylation induced by LPS. These effects could be blocked by RU486, ICI182,780 or JB-1(P <0.05).7. LPS could significantly increase the phosphorylation level of IkB. RU486 or JB-1 co-treatment could also block the inhibitory effect of Rg1 on LPS-induced IkB phosphorylation(P<0.05). ICI182,780 could partly block the inhibitory effect of Rg1.The above data indicate that ginsenoside Rg1 has inhibitory effect on LPS-induced inflammation in BV-2 microglial cells. The mechanism might be related to the activation of GR, IGF-ⅠR and ER signaling pathways. This study provides a new target for neurodegenerative disease therapy.