Objective: To investigate the effect of electroacupuncture (EA) on thymus and spleen and apoptosis of thymocytes in morphine withdrawal rats. Methods: Rat abstinence syndrome model was established by continuous muscular injection of morphine (with the injected doses increasing gradually from 4 mg to 140 mg/kg

1～3 times/d) to the hind limbs for 15 days. A total of 24 Wistar rats were randomly and evenly assigned to normal control group

abstinence syndrome (AS) group and EA (ST-36) group. The net weight of the thymus and spleen were detected and recorded.TUNEL method was applied to mark the apoptosis of thymocytes. EA (2～100 Hz

1～2 mA) was applied to bilateral “Zusanli”(ST 36) for 30 min

once daily

continuously for 7days. Results: In comparison with normal control group

a significant decrease of the weight of both thymus and spleen

and the thymus index and spleen index was observed in AS group(P<0.01). Comparison between AS group and EA group showed that the weight of both thymus and spleen of EA group increased significantly than that of AS group

and both thymus index and spleen index of EA group were bigger than those of AS group (P<0.01)

indicating that the effect of AS was reversed by EA. TUNEL method showed that the apoptosis rates of thymocytes in normal control

AS and EA groups were 5.7%

51.1% and 31.8% respectively

displaying that EA could suppress AS-induced apoptosis of thymocytes. Conclusion: EA of ST-36 may protect the immune organ and inhibit the apoptosis of thymocytes

which may account

at least partly

for the suppression of EA on immune organ impaired by morphine.