Figure 3.

Effect on Directed Motility and Surveillance of P2Y₁₂ and THIK-1 Block in Hippocampal Slices

(A and B) Effect of (A) PSB-0739 (PSB) to block P2Y₁₂ receptors (contrast with Figure 1C) and (B) tetrapentylammonium (TPA) to block THIK-1 channels, on directed motility (quantified in K) toward a pipette (arrow) filled with 1 mM ATP (and Alexa 488, white, for visualization). Images taken at times shown after placing the pipette; colors as in Figure 1A.

(C and D) Long-term stability of surveillance revealed by (C) images taken 5 min apart in control conditions, showing many process extensions (green) and retractions (red), and (D) time course of surveillance and ramification indices (see STAR Methods).

(E and F) As for (C) and (D) but with application of PSB-0739 to block P2Y₁₂, showing no significant effect (see L) on surveillance and ramification.

(G–J) As for (E) and (F) but applying TPA (G and H) or isoflurane (I and J) to block THIK-1, showing reduced ramification and fewer process extensions and retractions with THIK-1 blocked.

(K) Time course of directed motility quantified as reduction of the “clear area” not occupied by microglia around a laser-damaged spot (white polygon on A and B; see STAR Methods and Movie S3) in control conditions (n = 10) and with PSB (n = 6) or TPA (n = 7) present.

(L) Mean effects of drugs on surveillance (averaged over last 5 min in each drug). Number of microglia shown on bars; p values compared with control data (white bar, averaged 35–40 min in D) were from Mann-Whitney tests. A higher [PSB] is used in (A) than in (E), because PSB blocks P2Y₁₂ receptors competitively (Hoffmann et al., 2009) and a high [ATP] is used in (A). All data are from P12 rat. Data are represented as mean ± SEM. See also Figures S1 and S4.