Protection role of silent information regulator 1 in toxicity of activated BV-2 cells to PC12 ceils

Objective To observe the effects of silent information regulator 1 （SIRT1） on toxicity of activated BV-2 to PC12 cells and the possible mechanisms. Methods BV-2 microglial cells and PC12 cells were routinely cultured in vitro; ELISA was used to measure to the levels of tumor necrosis factor-α （TNF-α） and interleukin-6 （IL-6） stimulated by lipopolysaccharide （LPS, 1 μg/mL） in BV-2 cells. MTT assay was employed to identify the cell viability of PC12 cells injured by culture medium of activated BV-2 and determined the suitable concentrations of resveratrol （a potent SIRT1 activator, 5, 10, 25, 50 and 100 μmol/L） and nicotinamide （a known SIRT1 inhibitor, 5, 10, 25 and 50 mmol/L）. PC12 cells were divided into groups as follows： control group II, LPS＋BV-2 co-cultred group, resveratrol treatment group and nicotinamide treatment group （pretreated with resveratrol or nicotinamide for 2 h, and then subjected to culture medium of activated BV-2 cells, in the presence of resveratrol or sirtinol for 18 h）; the cell viability was measured by OD value in MTT assay, and the expressions of SIRT1 and acetyl-p53 were detected by Western blotting. Results TNF-α and IL-6 secretions increased gradually at 6, 12 and 24 h after LPS being induced BV-2, with significant difference between each two time points （P〈0.05）. PC12 cell viability decreased in the LPS＋BV-2 co-cultured group as compared with that in the control group I, LPS treatment group and BV-2 supernate group （P〈0.05）. The cell viability of cells in the 100 μmol/L resveratrol treatment group and 50 p, mol/L niacinamide treatment group decreased as compared with that in the control group Ⅱ （P〈0.05）, therefore, 50 μmol/L resveratrol and 25 μmol/L nicotinamide were chosen in the next experiment. As compared with those in the control group III, the cell viability and SIRT1 expression significantly decreased, and acetyl-p53expression significantly increased in the LPS＋BV-2 co-cultured group （P〈0.05）; as compared with those in the in the LPS＋BV-2 co-cultured group, the cell viability and SIRT1 expression significantly increased, and acetyl-p53 expression significantly decreased in the 50 μmol/L resveratrol treatment group, and opposite results were noted in the 25 μmol/L nicotinamide treatment group （P〈0.05）. Conclusion SIRT1 can inhibit toxicity of activated BV-2 to PC12 cells, the mechanism of which is partly via p53 activation. Key words: Silent information regulator 1;  Parkinson＇s disease;  BV-2 cell;  PC12 cell; p53