Abstract: Objective To observe the effect of Tongqiaohuoxue decoction on cognitive impairment in rats with traumatic brain injury and explore the mechanisms. Methods 70 Sprague-Dawley rats were randomized into normal group (n=10), sham operated group (n=20), untreated group (n=20) and treatment group (n=20). Controlled cortical impact device was utilized to establish traumatic brain injury model. The treatment group received Tongqiaohuoxue decoction 5 ml/d, and other groups received distilled water. The cognitive function of rats was evaluated with Morris water maze 1, 2, 3, 4 weeks post operation. And the rats were sampled to test the expression of brain-derived neurotrophic factor (BDNF) and synaptophysin (Syn) I in hippocampus through immunohistochemistry. Results The escape latency was longer in the untreated group than in the normal group in all the time points (P<0.05), and was longer in the treatment group than in the normal group 1 and 2 weeks after injury (P<0.05), with no significant difference 3 and 4 weeks after injury (P>0.05). And it was shorter in the treatment group than in the untreated group 3 and 4 weeks after injury (P<0.05). The percentage of swimming time was lower in the untreated group than in the normal group in all the time points (P<0.05), and was lower in the treatment group than in the normal group 1, 2, and 3 weeks after injury (P<0.05), with no significant difference 4 weeks after injury (P>0.05). And it was higher in the treatment group than in the untreated group weeks after injury (P<0.05). The BDNF expression was lower in the untreated group than in the normal group 1 and 2 weeks after injury (P<0.05), with no significant difference 3 and 4 weeks after injury (P>0.05). It was higher in the treatment group than in the normal group 4 weeks after injury (P<0.01), and was higher in the treatment group than in the untreated group 2, 3 and 4 weeks after injury (P<0.05). The Syn I expression was lower in the untreated group than in the normal group in all the time points (P<0.001), and was lower in the treatment group than in the normal group 1, 2 and 3 weeks after treatment (P<0.01). And it was higher in the treatment group than in the untreated group 3 and 4 weeks after injury (P<0.01). Conclusion Tongqiaohuoxue decoction could improve the cognitive function in rats with traumatic brain injury. The change in expression of BDNF and Syn I might be associated with the improvements.

Key words: traumatic brain injury, cognitive impairment, Tongqiaohuoxue decoction, rats