Effects of dexmedetomidine on postoperative cognitive function and hippocampus brain-derived neurotrophic factor and choline acetyltransferase expression in rats

Objective To investigate the effects of dexmedetomidine on postoperative cognitive function in aged rats and hippocampal brain-derived neurotrophic factor(BDNF)and choline acetyltransferase(ChAT)expression.Methods One hundred and forty-four aged male SD rats,weighing450-500 g,were randomly divided into 3groups,normal control group(group C,n=48),reduction of the fracture model group(group M,n=48),dexmedetomidine group(group D,n=48).In group D dexmedetomidine 3μg/kg was injected iv immediately after,followed by infusion of dexmedetomidine at a rate of 3μg·kg-1·h-1until the operation over.Morris water maze tests were performed on preoperative 1day and postoperative 1day,3days and 7days.The escape latency and swimming distance were recorded.After water maze test,the animals were sacrificed and their hippocampi were removed in each point for determination of BDNF and ChAT contents by ELISA,the expression of hippocampal BDNF and ChAT determination by immumohistochenistry.Results Compared with group C,the escape latency was prolonged and swimming distance of the water maze test was extended on postoperative 1day,3days in group M and postoperative 1day in group D,the expression of BDNF and ChAT were decreased(P0.05).Compared with group M,the escape latency and swimming distance of the water maze test were shortened on postoperative 1day,3days in group D,the expression of BDNF and ChAT were increased(P0.05).Compared to postoperative 1day,the the escape latency and swimming distance of the water maze test was shortened on postoperative 3days in group D and postoperative 7days in group M,and the expression of BDNF and ChAT were increased(P0.05).Conclusion Dexmedetomidine can improve cognitive function in aged rats,the mechanism may be related with dexmedetomidine enhances the expression of BDNF and increase the expression of ChAT in hippocampus.