DCEF effects on microglial cells. (A) The viability of resting and LPS-activated BV2 mouse microglial cells (4–5 replicates, n total=1350–2511) as well as (B) the total percentage of microglial cells specifically presenting protrusions (4–7 replicates, n total=2314–2723) were both influenced by DCEFs. (C) The total length of protrusions in resting (4–5 replicates, n total=423–670) and LPS-activated BV2 cells (6–7 replicates, n total=522–877) was also affected by various DCEFs. (D) Polar distribution of protrusion angles (each dot represents the angle of a single protrusion). Quiescent BV2 cells reoriented parallel to the DCEF when exposed to 100V/m (6–7 replicates, n total=522–877), but protrusion orientation was evenly distributed (i.e. did not show any specific directional preference) in LPS-activated BV2 cells in all conditions (4–5 replicates, n total=423–670). (E) Total cell body length was similar in all conditions for resting microglia (4–5 replicates, n total=437–593) but was significantly reduced following LPS treatment (6–7 replicates, n total=263–371). (F) Polar distribution of the cell body angles (each dot represents the angle of a single cell body). Cell body orientation was similar in all DCEF intensities for LPS-activated BV2 cells but was parallel to the DCEF at 50 and 100V/m for resting BV2 cells (6–7 replicates, n total=263–371). (G-N) Photomicrographs of double phalloidin (F-actin, red) and DAPI (nucleus, blue) immunofluorescent staining showing the morphological and orientational changes in BV2 microglial cells in response to DCEFs. Scale bar: 20 µm. (A-B, C, E) Data are presented as LS-means ± SEM. Statistical analyses: (A-B) ANOVA (split-plot-type, binomial), (C, E) ANOVA (split-plot-type) following log transformation, (D) Kuiper’s Test of Uniformity, and (F) chi-square test using grouped data (number of classes = 8 with identical divisions for interval 0 to 180°). **P<.01, ***P<.001 vs 0V/m; ##
P<.01, ###
P<.001 vs 25V/m; &
P<.05, &&
P<.01, &&&
P<.001 vs 50V/m; ∞∞P<.01, ∞∞∞P<.001 vs resting cells (-LPS). DCEF, direct current electrical field; LPS, lipopolysaccharide; LS, least square; V/m, Volt/meter.