Ultrastructural changes of neurons in rats with diffuse axonal injury

Objective To observe the ultrastructural characteristics and dynamic changes of neurons in rats with diffuse axonal injury (DAI). Methods Thirty-two SD rats (4 for sham operated group, 28 for injury group) and a self-made rotating injury device were used. The heads of rats in injury group were rotated immediately in the coronal plane by 90~ to the anticlockwise direction. The injured rats were killed at 30 min, 2, 6, 12, 24, 36 and 72 h post injury (4 rats each time) respectively. Tissue slides of the brain were made and observed under transmission electron microscope. Results The sign of various severity ofaxonal swelling and discontinuity was observed at early stage (30 min) in injury group ,the scores of damage degree were tested in rank sum test, and the scores suggested that the damage degree of axon in injury group was more severe than that in sham group (P＜0.05). Damage degree ofpericaryon in injury group was more severe than that in sham group (P＜0.05) except 30 min group and 72 h group (P＞0.05). Conclusions DAI was caused by primary injury and insecondary injury in common, insecondary injury aggravates axonal injury, which causes clinical symptom accordingly. Mechanism of axonal injury is different with that of cellular injury, and their progress of pathology is different. Key words: Diffuse axonal injury;  Diffuse axonal;  Neurons;  Cellular structures