Effect of Electroacupuncture on LTP in depression like rat’s hippocampus

Objective: To observe the effect of Electroacupuncture (EA) on long-term potentiation (LTP) in hippocampi of depression rats established by chronic unpredictable mild stress, and to explore the correlation between the antidepressant effect of EA and the regulation of hippocampal synaptic plasticity. Methods: Healthy adult female SD rats were divided into control (n = 15), CUMS (n = 15) and CUMS + EA groups (n = 15). Rats in the control group were fed normally. The CUMS group and CUMS+EA groups contained depressed model rats established by chronic unpredictable mild stress for 4 weeks. After modeling, the rats in the CUMS group and control group were fed normally for 3 weeks. Rats in the CUMS+EA group were treated with EA at the Siguan points for 3 weeks. After treatment, the detection of LTP was carried out in three groups. Results: ①Behavioral tests results: After modeling, compared to the control rats, depression-like rats exhibited lower weight increase ratio, lower sucrose preference ratio, less number of line crossing and number of rearing. After EA treatment, the weight increase ratio, sucrose preference ratio, numbers of line crossing and numbers of rearing were improved. ② LTP results: As the time went on, high-frequency stimulation of short duration induced stable LTP at a high level in the hippocampal Schaffer collateral and CA1 region of control rats and depression-like rats with EA. LTP was significantly inhibited in depression-like rats. There was a significant difference between depression-like rats, depression-like rats with EA and control rats. Conclusion: Chronic unpredictable mild stimulation (CUMS) can lead to depression like behavior in rats, and LTP inhibition in hippocampi in rats. The EA at Siguan points can rectify depression like behavior of rats caused by CUMS, and induce stable LTP in hippocampi in depression like rats. It is suggested that EA can improve the LTP of depression-like rats, which may be one of its mechanisms in antidepressant.