To investigate the influence of age on prognosis of intracerebral hemorrhage (ICH) in the mouse model.

Male C57 mice of 8 weeks old and 52 weeks old were divided into 4 groups: ICH group and sham-operated group for each age stage (n=6 in each group). Blood pressure was measured by noninvasive tail-cuff method. Experimental ICH was induced in mice by injection of autologous blood in the corpus striatum, the sham-operated group required only a needle injection into the corpus striatum. MRI scan was implemented 1 day and 3 days post operation to determine whether the model was successful. Modified neurologic severity scores (mNSS) were used to evaluate the neurological deficits of mice at 1, 3, 7 and 14 days post ICH. The survival of the 4 groups of mice was documented and Kaplan-Meier survival analysis was performed. HE (haematoxylin & eosin) staining was performed on the 4 groups of mice at 1 day and 3 days post modeling. Texas Red dye-labeled dextran was injected through the tail of the mice. The area of dye exudation in the brain was used to reflect the permeability of the blood brain barrier (BBB).

The pulse pressure of 52-week-old mice was significantly higher than that of 8-week-old mice [41.6±5.9 mmHg vs. 26.8±5.0 mmHg, P=0.003]. MRI scan revealed hematoma in the striatum of ICH group at 1 day and 3 days post modeling. The volume of hematoma was significantly increased compared with sham-operated group (P<0.05), which indicated that the model of ICH was successful. HE staining showed that hematoma was present at 1 day and 3 days post ICH modeling and there were different degrees of inflammatory cell infiltration in surrounding areas. Texas Red dye-labeled dextran exudation area at 1 day post ICH modeling was larger than that at 3 days post modeling (P=0.002). The differences in hematoma volume shown by MRI scan, neurological function scores at different time points, survival time, hematoma area assessed by HE staining and Texas Red dye-labeled dextran exudation area reflecting BBB permeability between the 2 age groups were not statistically significant (all P>0.05).

The age might not be associated with the prognosis of ICH in the mouse model.

Cerebral hemorrhage; Age factors; Prognosis; Mice