Effects of paraquat on proliferation and neurogenesis of neural stem cells by promoting secretion of IL-1β by microglia

BackgroundParaquat (PQ) is a widely used herbicide that exerts neurotoxicity. The effects of PQ on neural stem cells (NSCs) through microglia mediated neuroinflammation remain limitedly studied. ObjectiveTo investigate the effects of PQ on the proliferation and neurogenesis of NSCs through neuroinflammation mediated by microglia.MethodsMicroglial cell lines (BV2 cells) and primary NSCs were used. BV2 cells were exposed to 0, 1, 3.3, 10, 33, and 100 μmol·L−1 of PQ for 6 h followed by viability assessment. The highest PQ concentration that had no effect on cell viability was selected as the final exposure concentration (33 μmol·L−1). To exclude the direct effect of PQ on NSCs, after the BV2 cells were cultured in complete medium containing 33 μmol·L−1 PQ for 6 h, the BV2 culture medium was replaced by NSCs complete medium without PQ for 24 h. The concentration of interleukin-1β (IL-1β) in supernatant was detected by enzyme-linked immune sorbent assay. Besides, in order to detect the effects of IL-1β on NSCs proliferation and neurogenesis, NSCs isolated from hippocampus of adult mice were cultured in the supernatant obtained above and divided into four groups: control supernatant + control antibody, control supernatant + IL-1β neutralizing antibody (10 ng·mL−1), PQ supernatant + control antibody, PQ supernatant + IL-1β neutralizing antibody (10 ng·mL−1). Proportion of Ki67-positive NSCs was detected by flow cytometry (FCS) and immunofluorescence after 24 h culture, and neurogenesis was detected by FCS and immunofluorescence after 3-7 d of culture. ResultsThe IL-1β concentration in the supernatant of BV2 cells was significantly increased after the 33 μmol·L−1 PQ exposure compared with the control group (t=3.020, P