Objective:To investigate the effects of propofol on pyramidal neuron apoptosis in hippocampus of neonatal rats. Methods: Forty-twoseven-day-old male and female Sprague Dawley rats were randomly divided into three groups(n=14):group A received intraperitoneal 0.9% normal saline(7.5 ml/kg)once per day for seven days as control;group B received 0.9% normal saline(7.5 ml/kg)once per day for six days and propofol(75mg/kg)on the seventh day;group C received propofol(75 mg/kg)once per day for seven days. Two animals of each group were tested for blood glucose with tails cut off 3 hours after the last intraperitoneal injection

and six animals of each group were decapitated 5 hours after the last intraperitoneal injection for determination of caspase-3 expression with immuno-histochemistry. The other six animals of each group were decapitated after 3 weeks for microscopic examination. Results:Compared with group A

caspase-3 expression significantly increased while the number of pyramidal neurons decreased to different degree in both group B and C. More evident changes of the above were discovered in group C than that in group B

and the morphous of pyramidal neurons altered were only found in group C. Conclusion:The fact that increased caspase-3 expression leads to pyramidal neurons deletion to different degree was found in the rats which had received propofol.But the morphous ofpyramidal neurons altered onlywhen propofol had been repeatedlyinjected.