Abstract: △Corresponding Author E-mail： katherine69@yeah.net Abstract:Objective To explore the protective effect of Mip1 on cerebral edema by observing the Mip1 expression of perihematoma in intracerebral hemorrhage (ICH) rat model. Methods Ninety male SD rats were randomly divided into sham-operated group (n = 15) and ICH group (n = 75). ICH group was equally subdivided into 6 h, 12 h, 1 d, 3 d, and 7 d groups according to cerebral hemorrhage time, 15 in each group. Hematoma was formed by infusing autologous femoral artery blood into the right caudate nucleus. Rats were killed at the above time points, brain tissues around hematoma were taked. The pathological morphological changes in brain tissue around hematoma were observed using HE staining. The water content of brain (BWC) was measured with dry /wet weight method, and immunohistochemistry was used to analyze the average optical density value of Mip1 protein in perihematoma. Results Neuronal cell body of perihematoma was significantly decreased after ICH, the cytoplasm light staining, Nissl body reduced obviously in cytoplasm, and edema fissure appeared around cells, however, no obvious changes of nerve cells were detected in sham- operated group. Brain edema gradually increased at 6 h, and reached peak at 3 d (all P＜0.05), then up to normal at 7 d after intracerebral hemorrhage (P＞0.05). A large amount of brown Mip1 positive cells were found to distribute in cytoplasm and nucleus of perihematoma after intracerebral hemorrhage. The Mip1 protein expression level was higher in 6 h after intracerebral hemorrhage than that in sham-operated group (all P＜0.05), and returned to normal level at 7 d (P＞0.05). Conclusion The high expression of Mip1 after ICH is in line with the trend of the brain edema development, and shows that the activation of Mip1 may participate in the pathological process of hemorrhagic cerebral edema.

Key words: cerebral hemorrhage, brain edema, rats, Sprague-Dawley, water content of brain, Mip1