Fig 2: Flow cytometry gating strategy for CD86 set. Forward and side scatter were used to remove debris (A). Dead cells internalize the Zombie dye and give a positive signal, allowing for further exclusion (B). Singlets were then selected using height and area of forward scatter (C). Microglia and macrophages were identified by selecting cells that were positive for CD11b (D). CD45 was then used to differentiate between infiltrating macrophages (CD45high) and resident microglia (CD45low) (E). A quadrant system was created paring KOR vs. CD86 (M1 marker) into CD45-high and CD45-low cell populations (F)

Fig 3: Quantification of microglia/macrophages expressing CD206 (M2 marker) and KOR. Morphine significantly increases the number of CD206+ microglia (A) and CD206+ macrophages (C) after 3 days of administration. Morphine administration also increases the number of CD206 + microglia and macrophages expressing KORs (B and D). Results shown as Mean ± S.E.M. *p < 0.05, n = 6