Figure 5

Microglial depletion in CD11b-HSVTK slice cultures by ganciclovir treatment also results in a strong increase in neuronal cell death in response to excitotoxicity. Graphs represent the percentages of neuronal cell death per hippocampal region (A to C) in response to 0, 10, and 15 μM NMDA in wild type (TK- GCV+) and microglia-depleted CD11b-HSVTK slice cultures (TK + GCV+). Microglial depletion alone did not lead to a significant increase in neuronal cell death (A-C; CNTR). However, in the absence of microglia, neuronal cell death in response to NMDA-induced excitotoxicity was severely enhanced in the DG (A) and CA3 (B). Almost no microglia cells were present when TK slices were treated with GCV (E) compared to wild type slice cultures (D). Confocal images clearly show the effect of microglial depletion on neuronal degeneration in response to 15 μM NMDA (F-K). Here, in the absence of microglia, neuronal cell death was significantly increased in the DG from 19.5% to 79.2% (F,G) and in the CA3 from 56.6% to 90.3% (H, I). In the CA1 (J,K) no significant effect in response to 15 μM NMDA was observed between wild type and TK slice cultures (96.2% versus 96.6%, respectively). Data are a summary of three individual experiments with at least 6 slice cultures per condition. Bars indicate mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ANOVA. Scale bars indicate 300 μM (D,E) and 75 μM (F-K).