Figure 17

Effect of hypothermia on microglial migration in vivo . To assess the effect of therapeutic hypothermia on microglial migration in vivo, focal stab injury was created by placing a needle in the cortical area of the brain through a guide cannula. Local hypothermia (33 °C) using cold water circulation through a cooling coil was initiated either six hours before or after the needle injury, and maintained for 66 to 78 hours as indicated (A). Asterisks indicate the injury site. Horizontal sections of rat brain were subjected to microglial immunohistochemistry (Iba-1, green) (B). A representative microscopic image for each condition is shown (magnification, x40). Scale bar = 1 mm. Data acquisition and immunohistological intensity measurement of Iba-1 staining was performed with a NIH image J program (C). To count the Iba-1 positive cells, three concentric circles with constant interval were placed in the peri-region of the injury site (asterisk) in the sub-threshold image of the six independent sections. Three animals were used for each experimental group. The cells in the three circles were counted and statistically analyzed (D). Results are the mean ± SD. *P < 0.05, **P < 0.01; different from the same circle under normothermia (37 °C). #P < 0.05; different from the two conditions indicated.