Abstract:

Objective To investigate the protective effect of rosaminic acid （RA） on astrocyte injury induced by β-amyloid protein 1-42 （Aβ_1-42） and the inhibitory effect of the inflammatory factor release， and to clarify the related mechanism. Methods After primary culture，the astrocytes were divided into control group， Aβ_1-42 group （5 μmol?L^－1）， different concentrations（20，50，100 μmol?L^－1） of RA+Aβ_1-42 groups， nuclear factor E2-related factor 2（Nrf2） inhibitor ML385 group，and ML385+RA+Aβ_1-42 group.The astrocytes were pretreated with different concentrations （20，50，100 μmol·L^－1） of RA for 24 h and then treated with Aβ_1-42 at a final concentration of 5 μmol·L^－1 for 24 h，and the final concentration of 10 μmol·L^－1 ML385 was pretreated for 6 h before added RA in ML385 group. The cell activities in various groups were detected by MTT method， the lactate dehydrogenase（LDH）release rates of the cells in various groups were detected by LDH kits， the levels of interleukin-1β（IL-1β） and tumor necrosis factor-α（TNF-α） in the cells in various groups were detected by enzyme linked immunosorbent assay （ELISA） kits， the levels of nitric oxide （NO） in culture medium in various groups were detected by Griess method， the expressions of glial fibrillary acidic protein （GFAP） and Nrf2 in the cells in various groups were detected by immunofluorescence method，and the expression levels of GFAP， Nrf2 and heme oxygenase-1 （HO-1） proteins in the cells in various groups were detected by Western blotting method. Results Compared with control group， the cell activity in Aβ_1-42 group was significantly decreased（P<0.01）， the LDH release rate and the levels of IL-1β， TNF-α， and NO were significantly increased（P<0.01）， the fluorescence intensity of GFAP was significantly enhanced，the fluorescence intensity of Nrf2 was significantly reduced，the expression level of GFAP protein in the cells was significantly increased（P<0.01），and the expression levels of Nrf2 and HO-1 proteins were significantly decreased （P<0.01）. Compared with Aβ_1-42 group， the cell activities in different concentrations of RA+Aβ_1-42 groups were significantly increased （P<0.01）， the LDH release rates and the levels of IL-1β，TNF-α， and NO were significantly decreased （P<0.01）， the fluorescence intensities of GFAP were significantly decreased，the fluorescence intensities of Nrf2 were significantly enhanced，the expression levels of GFAP protein were significantly decreased（P<0.01）， and the expression levels of Nrf2 and HO-1 proteins were significantly increased （P<0.01）. Compared with RA （50 μmol?L^－1） +Aβ_1-42 group， the cell activity in ML385+Aβ_1-42+RA group was significantly decreased（P<0.01）， the LDH release rate and the levels of IL-1β， TNF-α， and NO were significantly increased（P<0.01）， the fluorescence intensity of GFAP was significantly enhanced，the fluorescence intensity of Nrf2 was significantly，the expression level of GFAP protein was significantly increased （P<0.01），and the expression levels of Nrf2 and HO-1 proteins were significantly decreased （P<0.01）. Conclusion RA can inhibit the release of the inflammatory factors and NO， the mechanism of protecting astrocytes from damage may be related to the activation of Nrf2 / HO-1 pathway.

Key words: Rosmarinic acid, Astrocytes, β-amyloid protein, Nuclear factor E2-related factor 2, Heme oxygenase-1