Objective To study the underlying mechanism of electroacupuncture(EA) in relieving depression.Methods A total of 30 Wistar rats were randomly divided into normal control group(n=10)

model group(n=10) and EA group(n=10).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 min

once daily for 14 days.The expression(option density) of hippocampal somatostatin(SS) and SS mRNA was detected by using immunohistochemistry and reversed transcription-polymerase chain reaction(RT-PCR) techniques respectively.Results Compared to normal control group

the crossing movement and rearing movement times of open-field test

and sucrose consumption in model group decreased significantly(P<0.01)

and hippocampal SS and SS mRNA expressions were downregulated remarkably(P<0.05).Compared to model group

the crossing movement and rearing movement times in EA group increased considerably(P<0.01)

and hippocampal SS and SS mRNA expressions were upregulated remarkably(P<0.05).No significant difference was found between EA and normal control groups in SS and SS mRNA expression.Conclusion EA can effectively improve depression rats' behavior activity and upregulate hippocampal SS and SS mRNA expression.