Introduce a model for diffuse brain injury in rats

Diffuse brain injury occurs in nearly half of all severe of clinical traumatic brain injuries and has been associated with high mortality. Brain edema is a mortal pathological condition, which is commonly observed in diffuse brain trauma. In the current study, a new model producing diffuse brain injury, without focal brain lesions, was developed in rats, for first time in Iran. Matrials and Diffuse brain trauma was produced in 45 male rats that they were divided into three groups; control, sham, and trauma group. Rats in two later groups underwent general anesthesia using a mixture of halothane, oxygen and nitrous oxide. A stainless steel disc (1cm in diameter) was firmly fixed to central portion of skull vault using dental acrylic. In the trauma group, a weight of 450g was allowed to drop from the 2m height onto the disc when trauma device was ready. All animal were mechanically ventilated during the treatment. In all groups, pathological studies and measurement of brain edema were performed at 24 hours following injury. Brain edema was evaluated by water content of brain and extravasation of Evans blue (E.B) dye. The results of present study indicated that this technique induces a diffuse brain injury in the rats, as it was shown by a siginificant increase of brain water content in the trauma group compared to the control and the sham groups (p<0.05). In addition, the extravasation of E.B content was significantly more in the trauma group than other two groups (p<0.001). Pathological examinations showed diffuse brain ischemia and brain edema as well. Taken overall, this technique is introduced as a successful and suitable model for studying neuronal and vascular changes associated with diffuse brain injuries.