Involvement of Microglia Activation in the Lead Induced Long-Term Potentiation Impairment
Figure 3
Pb activated microglia, enhanced TNF-α and IL-1β secretes, iNOS expression, and induces hippocampal neuronal injury.
Purified microglia cells were seeded in 12-well culture plates. Cells were treated with vehicle (control) (A) or Pb (50 µmol) (B) for the indicated times. Microglia activation was detected by immunocytochemistry (OX42). (A) control; (B) 50 µmol Pb for 48 h. (C) The results were quantified. Results (A and B) are expressed as the mean ± S.D. of average activated cell rate in random fields (n = 20). **P<0.001 compared with control groups. Scale bar indicates 50 µm. iNOS was detected by immunofluorescence staining. Activation of iNOS was evaluated by measure the average fluorescence of iNOS-immunoreactive cells (D, E). (F) The results were quantified and are expressed as the mean ± S.D. of average fluorescence of iNOS-immunoreactive cells in random fields (n = 20). ** P<0.001 compared with control groups. Scale bar indicates 50 µm. TNF-α (G) and IL-1β (H) were determined by ELISA. Purified microglia were cultured with vehicle (control) or Pb (50 µmol) for 48 h for the TNF-α and IL-1β assay, respectively. ** P<0.001 compared with control groups. The purified microglia were co-cultured with hippocampal neurons for 48 h after culturing with vehicle (control) (L, P, T) or Pb (50 µmol) (M, Q, U) for 48 h. Apoptosis of hippocampal neurons was detected with in situ TUNEL (green fluorescence). Degeneration of hippocampal neurons was evaluated by counting the number of apoptotic neurons. As compared with the co-culture method, hippocampal neurons were also treated with vehicle (control) (J, N, R) or Pb (50 µmol) (K, O, S) directly for 48 h. (I) The results were quantified and are expressed as the mean ± SD of apoptotic neurons percentage in random fields (n = 20). ** P<0.001 compared with control groups. Scale bar indicates 50 µm. CC in figure means co-culture method; DS in figure means direct stimulation method.