OBJECTIVETo explore the effects of electroacupuncture (EA) on behavioral function and synaptic plasticity in hippocampal CA3 area in rats with chronic stress depression.

METHODSAccording to the random number table method, 144 SD male rats were assigned into a blank group, a model group, an EA group and a fluoxetine group, then each group was divided into a 7 d subgroup, a 14 d subgroup and a 21 d subgroup, 12 rats in each subgroup. The chronic mild unpredictable stress stimulus combined with lonely breeding were applied to establish the depression model of rats, which was performed simultaneously with intervention treatment. The rats in the EA group were treated with EA (dilatational wave) at "Shenting" (GV 24) and "Baihui" (GV 20), while the rats in fluoxetine group were treated with intragastric administration of fluoxetine, once daily. With open-field test, sugar consumption experiment and transmission electron microscope, the changes of behavior and neuronal synapse inhippocampal CA3 area were observed.

RESULTSOn 7 d, 14 d and 21 d, compared with the blank group, the open-field test score, sugar consumption and body mass were significantly lower in the model group (all<0.01); compared with the model group, the open-field test score, sugar consumption and body mass were significantly higher in the EA group and the fluoxetine group on 14 d and 21 d (<0.01,<0.05). On 14 d and 21 d, compared with the blank group, the synapse in hippocampal CA3 area was significantly lower in the model group (both<0.01); compared with the model group, the synapse in hippocampal CA3 area was significantly higher in the EA group and the fluoxetine group (<0.01,<0.05). The neurons cells in hippocampal CA3 area in the model group showed pyknosis and deformation from 7 d with fusion structure and unclear boundary of synapse, which were significantly improved on 21 d; the neurons cells in hippocampal CA3 area in the EA group and the fluoxetine group were significantly improved from 14 d and restored to normal level on 21 d, in addition, the structure of synapse restored to normal level.

CONCLUSIONSEA is involved in the regulation of synaptic plasticity in hippocampal CA3 area, and promotes the recovery of depression symptoms.