Mild Traumatic Brain Injury Produces Spatial Learning and Memory Deficits in Rats

Objective: To investigate the effect of mild brain trauma on the spatial learning and memory of rats and its underlying mechanism.Methods: One-hundred and twenty SD rats(bisexual each half) were randomly divided into four groups: female control group,female experimental group,male control group and male experimental group(n=30,respectively).All rats in the experimental groups were developed a lateral fluid percussion model of mild brain trauma.Morris water maze(MWM) test was used to assess the spatial learning and memory of rats at day 8 after operation.Serum COR levels were determined by using a standard radioimmunoassay kit and the expressions of brain-derived neurotrophic factor(BDNF) and tyrosine protein kinase B(TrkB) in hippocampus were measured by immunoreactivity quantitative analysis after MWM test.Results: At the 4th day of navigation task,the escape latency of rats in the experimental groups were significantly longer than those in the control groups(P0.01).In the probe trial,compared with those in the control groups,the times to reach platform location were longer and crossings over the platform area were less in the experiment groups(P0.05).The serum COR levels in the experiment groups were significantly higher(P0.01) and the expressions of BDNF and TrkB in hippocampus were lower(P0.05) than those in the control groups.Conclusion: Mild brain trauma leads to cognitive deficits in rats.The reduced expressions of BDNF and TrkB in hippocampus may underlie the cognitive impairment.