Effect of mild hypotherma on aquaporin 4 expressions and cerebral edema in experimental rats after intracerebral hemorrhage

Objective To study the effect of mild hypothermia on aquaporin 4 (AQP4) expressions and cerebral edema after intracerebral hemorrhage and the mechanisms of mild hypothermia on hemorrhagic brain edema. Methods The model of intracerebral hemorrhage (ICH) was established by infusing collagenase into right globus pallidus of the rat. The temperature was regulated by ice cubes and daylight lamp, which was modulated to an appropriate distance to the animals. Immunohistochemistry staining was used to detect the cerebral AQP4 expressions. Dynamic change of brain edema was observed through wet-dry weighing method. Results The brain water content (BWC) of injured side and level of AQP4 expression in perihematom tissue in ICH rats were obviously higher than those of the sham group (all P0.001). In the mild hypothermia group, the BWC and AQP4 expression level were obviously lower than those of the control group at every time point ( P0.05~0.01). The level of AQP4 expression was positively correlated with BWC (r=0.977, P0.001). Conclusion Mild hypothermia may relieve cerebral edema after ICH and inhibiting AQP4 expressions may be related with its mechanism.