Objective To study changes and significance of endothelin(ET) in rat cerebral concussion.Methods 80 Wistar male rats were used for animal model of cerebral concussion,which were sacrificed on 1,3,7,14 and 30 days after injury and the brain tissue were taken off. The expression of ET was studied in the course of cerebral concussion by means of immunohistochemistry.Results Typical clinical manifestation was observed in the 100 g group in which the pathological changes included cerebral vascular constriction and dilatation,congestion and edema of cerebral tissue,neuronal degeneration,necrosis,and obviously decreased even disappeared Nissl bodies.Increased expression of ET was observed on the first day,the positive area was seen in the plasma of endothelial cells in cerebral cortex,hippocampus,cerebellum and thalamus.ET expression peak occurred on the 7th day,the positive area was also found in the plasma of Purkinje cells in the cerebellum.Decreased ET expression was found on 14th day and returned to normal level on the 30th day.Conclusion The main pathological changes of cerebral concussion contained blood circulation disorder,and degeneration and necrosis of substantial cells.ET was involved in the brain tissue injury during the pathological process of cerebral concussion and might be related to regulation of cerebral vascular reaction,and neuron degeneration and necrosis.