The dynamic changes of microglial polarization around intracerebral hematoma in rats / 中华行为医学与脑科学杂志

ABSTRACT

Objective To investigate the dynamic changes of microglial polarization at the perihe-matoma area and provide timepoint evidence for interventing microglial polarization as well as studying the polarization mechanism after intracerebral hemorrhage ( ICH ) . Methods Healthy male Sprague Dawley (SD) rats were randomly divided into sham group,ICH-4 h,1 d,3 d,7 d and 14 d groups with 6 in each group. The rats in ICH groups were injected collagenase VII-s into the caudate nucleus to establish the in-tracerebral hematoma model and rats in sham operated group were treated with the same amount of saline. The brains were taken at 4 h,1 d,3 d,7 d,14 d in the ICH group,1 d in sham group. Microglia typeⅠ( M1, CD11b++CD86+) and microglia typeⅡ( M2,CD11b++Arg-1+) were examined by immunofluorescence and the number of M1 and M2 around hematoma were analyzed. Results ( 1) The M1 and M2 were both ob-served at 4 h after ICH and a small quantity of branches were still presented on M1. ( 2) M1 took the main position in acute stage (1~3 d),early subacute stage(3~7 d) and chronic stage (>14 d) after ICH.The number of M2 was elevated transiently in superacute (<24 h) and late subacute stage (7 d).The number of M2 (31.40±1.69) was more than M1 (21.43±1.81) at 4 h after ICH ( t=- 4.085, P=0.002),and the number of M2 (116.25±5.06) significantly exceeded M1 (85.75±7.32) again on day 7 ( t=-0.690, P=0.001). Conclusion M1 is in a dominant position in acute,early subacute and chronic stages after ICH;M2 is dominant in superacute and late subacute stages. Investigating the mechanism of M2 formation at acute period ( such as 4 h) or late subacute stage ( such as 7 d) ,and inhibiting M1 formation in the early subacute stage ( 1~3 d) have important significance for clinical treatment of ICH.