Effects of electroacupuncture on behaviors and expressions of SYN and PSD95 in hippocampus of rats with post-traumatic stress disorder

Objective: Electroacupuncture (EA) in the treating principle of “soothing the liver and regulating the kidney” was applied to intervion the rats with post-traumatic stress disorder (PTSD), and its effect on anxiety-like behavior, spatial learning and memory ability, and expressions of synaptophysin (SYN) and postsynaptic dense 95 (PSD95) in hippocampus of rats were observed to explore the underlying mechanism. Methods: Twenty-four male SD rats were randomly divided into control group, model group, and EA group, with 8 rats in each group. There was no intervention in the control group. The rest 16 rats were prepared for modeling. The single-prolonged stress & shock (SPS&S) method was used to establish the PTSD models. There was no intervention in the model group after modeling. In the EA group, “Bǎihuì (百会GV20)”“ Shéntíng (神庭GV24)”“Gānshū (肝俞BL18)”“Shènshū (肾俞BL23)” were manipulated with EA stimulation, intensity 1 mA, frequency 2/100 Hz, disperse-dense wave, and treatment was performed once a day, 20 min each time, for a total of 21 days. Open field test, elevated plus maze and Morris water maze tests were used to observe the behavioral differences of rats in each group. Immunohistochemical method was used to observe the differences of positive expressions of proteins SYN and PSD95 in hippocampus. Results: In the open field test, compared with the control group, the total traveling distance, the percentage of the time spent in the central cell and the numbers of the central cells crossing in the model group were all decreased (all P < 0.05). Compared with the model group, these indicators in the EA group were significantly all increased (all P < 0.05). In the elevated plus maze test, compared with the control group, the percentages of open arm staying time and entering times in the model group were both decreased (both P < 0.05). Compared with the model group, these indicators in the EA group were both significantly increased (both P < 0.05). The results of Morris water maze test showed that compared with the control group, the escape latency time and travelled distance of rats in the model group were all increased from day1 to day 4 (all P < 0.05), and the percentage of staying time in the target quadrant was decreased (P < 0.05). Compared with the model group, the escape latency time and travelled distance of EA group were both significantly shortened (both P < 0.05), and the percentage of staying time in the target quadrant was significantly increased (P < 0.05). The immunohistochemical results showed that, compared with the control group, the positive expressions of SYN and PSD95 in the hippocampus of the model group were significantly down-regulated (both P < 0.05). Compared with the model group, the positive expressions of SYN and PSD95 in the hippocampus of the EA group were significantly up-regulated (both P < 0.05). Conclusions: EA in the treating principle of “soothing the liver and regulating the kidney” can effectively relieve anxiety-like behavior and improve spatial learning and memory ability of rats with PTSD, and the mechanism is related to the up-regulation of the expressions of SYN and PSD95 in the hippocampus.