Objective To investigate the influence of electroacupuncture(EA) on 5-serotonin(5-HT) and acetyl cholinesterase(AChE) activities in hippocampus tissue in chronic stressed-induced depression rats.Methods Thirty-two Wistar rats were randomized into normal control group(n=10)

model group(n=11) and EA group(n=11).Chronic depression model was established by lonely raising

and chronic unpredictable mild stress for 21 days.EA(2 Hz

1 mA) was applied to "Baihui"(GV 20) and "Sanyinjiao"(SP 6) for 20 minutes

once daily for 14 days.5-HT and AChE expression of hippocampal CA 4 region was detected by using immunohistochemistry

and their integrated optical density(IOD)values were determined by using image analysis system.Results Compared with normal control group

IOD values of 5-HT and AChE immuno-reaction(IR) positive neurons in hippocampal CA 4 region of model group decreased significantly(P<0.05).In comparison with model group

the IOD values of 5-HT and AChE IR positive neurons of CA 4 region in EA group increased significantly(P<0.05).No significant differences were found between EA and normal control groups in IOD values of both 5-HT and AChE IR positive neurons.Conclusion EA can upregulate 5-HT and AChE expression in hippocampal CA 4 region in depression rats

which may contribute to its effect in relieving depression.