Effect of extracts of ginkgo biloba leaves on activation of RBL-2H3 cells

AIM: To investigate the mechanism of extracts of ginkgo biloba leaves (EGB) on degranulation from mast cells. METHODS: Wistar rats were randomly divided into 6 groups, including normal group, control group, high dose of EGB group (30 mg/kg), moderate dose of EGB group (10 mg/kg), low dose of EGB group (3 mg/kg) and positive control medicine group (azelastine, 5 mg/kg), each group had 10 rats (half female and half male). The experiment of passive cutaneous anaphylaxis reaction (PCA) and colorimetry were used to determine the effect of EGB on degranulation of mast cells in vivo. For in vitro study, various doses of EGB (200 mg/L, 100 mg/L and 50 mg/L) were added to the culture medium of RBL-2H3 cells cultured with 200 μg/L of dinitrophenyl (DNP) specific IgE overnight. The azelastine (30 mg/L) was selected as the positive control. The antigen (DNP-human serum albumin, DNP-HSA, 20 μg/L)-induced release of degranulation was measured by enzymatic assay, histamine by EIA, leucotriene C4 (LTC4), interleukin-4(IL-4) and tumor necrosis factor-α (TNF-α) by ELISA, respectively. In addition, the effect of EGB on phosphorylation of Akt and p38 was observed by Western blotting. RESULTS: The results showed that treatments with high dose of EGB (30 mg/kg) and moderate dose of EGB (10 mg/kg) were followed by a decrease in PCA of rats. All doses of EGB (200 mg/L, 100 mg/L and 50 mg/L) obviously suppressed the degranulation from RBL-2H3 cells, whereas results in high dose group (200 mg/L) and moderate dose of EGB group (100 mg/L) indicated significantly inhibitory effect on β-hexosaminidase, histamine, LTC4, IL-4,TNF-α, phosphorylation of Akt and p38 of RBL-2H3 cells induced by antigen. CONCLUSION: EGB may suppress the anaphylactic reaction by inhibiting the action of mast cells. Akt and p38 at least in part contribute to this event.