Role of histamine in brain protection in surgical brain injury in mice.

Surgical resection of brain tissue is associated with tissue damage at the resection margin. Studies of ischemic brain injury in rodents have shown that administration of L-histidine and thioperamide reduces ischemic tissue loss, in part by inhibition of apoptotic cell death. In this study we tested administration of L-histidine and thioperamide in surgical brain injury in mice. Mice were randomized to one of three groups: Sham surgery (n=18), surgical brain injury without treatment (SBI) (n=33), and surgical brain injury with combined l-histidine and thioperamide treatment (SBI+H) (n=29). Surgical brain injury was induced via right frontal craniotomy with resection of the right frontal lobe. L-histidine (1000 mg/kg) and thioperamide (5 mg/kg) were administered to the SBI+H group immediately following surgical resection. Postoperative assessment included neurobehavioral scores, Evans blue measurement of blood-brain barrier breakdown, brain water content, Nissl histology, and immunohistochemistry for IgG and cleaved caspase 3. Postoperative findings included equivalent neurobehavioral outcomes at 24 and 72 h in the SBI and SBI+H groups, similar histological outcomes between SBI and SBI+H, and similar qualitative staining for cleaved caspase 3. SBI+H had increased BBB breakdown on Evans blue analysis and a trend towards increased brain edema which was significant at 72 h. We conclude that combined treatment with l-histidine and thioperamide leads to increased BBB breakdown and brain edema in surgical brain injury.