OBJECTIVETo observe the effects of electroacupuncture (EA) on circadian rhythm of temperature and melatonin (MT) in depression rats model induced by chronic stress, so as to explore the biological mechanism of EA for depression.

METHODSTwenty-four SD rats were randomly divided into a control group, a model group and an EA group, 8 cases in each one. Rats in the control group were treated with normal diet for 21 days without any treatment. In the model and EA group, rat model was established by chronic unpredictable stress combined with solitarily feeding method, and rats in the EA group was treated with EA at "Baihui" (GV 20), "Yintang" (GV 29) 1 h before stress stimulation everyday, 2 Hz in frequency and intensity was favorable with the head of rat slightly shivering. The needles were retained for 20 min, once a day for totally 21 days. After EA treatment, open-field experiment was adopted to observe the behavioral improvement; the rats temperatures were monitored at six time points (2:00, 6:00, 10:00, 14:00, 18:00, 22:00) and orbital blood sampling was collected. The level of serum MT was tested by enzyme linked immunosorbent assay. The circadian rhythm changes of temperature and serum MT in each group were compared.

RESULTSThe numbers of horizontal movement and vertical movement in the model group were obviously lower than those in the control group (both P < 0.05), while those in the EA group were significantly improved compared with those in the model group (both P < 0.01). The circadian rhythm of temperature and MT disappeared in the model group, which was improved into normal level after EA treatment.

CONCLUSIONThe electroacupuncture has regulation effects on circadian rhythm of temperature and melatonin in depression rat model induced by chronic stress.