Establishment of modified "double injection of blood" subarachnoid hemorrhage induced delayed cerebral vasospasm model in rats

Objective The subarachnoid hemorrhage (SAH) models were established by modified injection of autologous blood into the rat cisterna magna and then assess the degree of delayed cerebral vasospasm. Methods The details of improved double injection of autologous blood is as folllows: (1) Stereotaxic apparatus was used to located the cisterna magna in the three-dimensional space. (2) Instead of manual injection, the micro-injection pump, which keep the volume and injection speed constant, was used. A total of 75 male SD rats were included in this study and randomly divided into the following three groups (n=25/group): sham group, control group and SAH group. SAH group, rats subjected to injection of autologous blood into the cisterna magna; control group, rats subjected to injection of the equal quantity saline; sham group, rats subjected to only explosion of atlanto-occipital membrane. The success rate and failure rate, neurological function, brain water content, changes of basilar artery, regional cerebral blood flow (rCBF) were observed. Results Neurological function in SAH group were significantly impaired as compared with sham group at day 1 (9.2±0.7 vs. 1.0±0.6, P=0.001). Brain water contents in SAH group were significantly increased as compared with sham group and control group at day1 [(79.98±0.11)% vs. (78.29±0.12)%, (78.39±0.13)%, P=0.001]. Hematoxylin and eosin (HE) staining results showed a significant reduce of basilar artery lumen diameter and area in SAH group than that in sham group at day5 [(325.200±15.156) μm vs. (461.000±22.705) μm, P=0.000; (80 739.200±7 297.735) μm2 vs. (167 124.200±7 067.155) μm2,P=0.000]. The result of rCBF of SAH group, measured by Laser speckle, also showed a significant decrease compared to sham group at day5 after SAH [(56.0±3.5)% vs. (97.2±1.7)%, (95.8±3.5)%, P=0.001]. Conclusion The stable and reliable subarachnoid hemorrhage model can be established by modified injection of autologous blood into the cisterna magna. Key words: Subarachnoid hemorrhage; Model; Cerebral vasospasm; Animal experimentation