Objective To investigate whether the effect of fluoxetine on cell proliferation involves Notch1 signaling in cultured neural stem cells (NSCs). Methods The MTT assay was used to evaluate cell viability. The expression of Notch1 signaling components (including Notch1 mRNA, Hes1 mRNA and Hes5 mRNA) were detected by real time PCR. Results (1) The cell viability was significantly decreased when the concentration of fluoxetine was more than 40μmol/L (P<0.01 or P<0.05). (2) When the cells were treated with the 10μmol/L, 15μmol/L and 20μmol/L fluoxetine for 48h, the cell viabilities in cell-conditioned media increased significantly more than that of the 0μmol/L group (P<0.01). (3) MTT assay showed the presence of fluoxetine strongly enhanced the cell proliferation (P<0.001) compared to control, while DAPT decreased cell proliferation (P<0.001). When adding fluoxetine and DAPT in combination, the cells of proliferation were declined (P<0.001) compared with fluoxetine group. (4) Inactivation of Notch signaling with DAPT lead to a rapid reduction in the expression of Hes1mRNA and Hes5mRNA compared with the control (P<0.001). After the treatment of fluoxetine for 48h, the expression of Notch1mRNA, Hes1mRNA and Hes5mRNA increased significantly compared with the control (P<0.001 or P<0.01). When NSCs were exposed to fluoxetine-conditioned medium with DAPT, real time PCR analysis revealed that the expression of Notch1mRNA, Hes1mRNA and Hes5mRNA were decreased relative to fluoxetine-conditioned medium without DAPT (P <0.001 in all case). Conclusion (1) Fluoxetine enhanced cell proliferation in cultured NSCs. (2) Fluoxetine activated the Notch1 signaling pathway in NSCs. (3) Notch1 signaling might play a major role in the proliferation of NSCs promoted by fluoxetine. |