Objective To observe the effect of electroacupuncture(EA)intervention on the levels of CD 4+and CD 8+lymphocytes in the plasma and thymus in anxiety disorder rats

so as to explore its mechanism underlying favorable regulation of immune function.Methods Thirty-four SD rats were randomly divided into control(n=10)

model(n=12)and EA(n=12)groups.The anxiety model was established by using chronic unpredictable emotional stress stimulation(fasting

water-deprivation

shaking

tail-clamping

forced warm-and cool-water swimming

electrical shock stimulation

etc.)for 15 days.EA(15Hz/25Hz)was applied to"Neiguan"(PC 6)and"Shenmen"(HT 7)for 15 min

once every other day for 15 days.The anxiety-like behavior was measured by elevated plus maze test.Anxiety reduction in the plus-maze is indicated by an increase in the proportion of time spent in the open arms(time in open arms/total time in open or closed arms)

and an increase in the proportion of entries into the open arms(entries into open arms/total entries into open or closed arms).While the contents and expression of CD 4+and CD 8+in the plasma and thymus tissues were measured by ELISA and immunohistochemistry

respectively.Results The values of proportions of open-arm entries(OE%)and the content of plasma CD 4+lymphocytes were obviously lower in the model group than in the control group(P<0.05)

and were significantly higher in the EA group than in the model group(P<0.05).Whereas

the content of plasma CD 8+lymphocytes was obviously higher in the model group than in the control group(P<0.05)and markedly down-regulated in the EA group after the treatment(P<0.05).The ratio of CD 4+/CD 8+was decreased in the model group in comparison with the control group(P=0.054)

and was significantly up-regulated in the EA group after EA stimulation(P<0.01).Compared with the control group

the expression levels(optical density

OD values)of CD 4+and CD 8+lymphocytes in the thymus tissue were obviously decreased in the model group(P<0.01).After EA

the expression levels of thymus CD 4+and CD 8+were remarkably up-regulated in the EA group(P<0.05).No significant changes were found in proportion of open-arm time(OT%

P>0.05).Conclusion EA can effectively relieve anxiety disorder in anxiety rats

which may be related to its effects in up-regulating plasma CD 4+

thymus CD 4+and CD 8+levels as well as CD 4+/CD8+ratio

and down-regulating plasma CD 8+content.