The Effects Of Electroacupuncture On Behaviors And Hippocampal Synaptic Plasticity In Depression Model Rats

ObjectiveDepression is one of the most common psychiatric disorders and the lifetime prevalence rate is up to15%-17%. The mechanism of depression is still unknown currently. To get further theoretical basis to clinical eletroacupuncture treatment of depression, this research was focus on studying the effects of electroacupuncture on hippocampal synaptic plasticity and the expression of AMPA and NMDA receptor subunits, which were closely related to the transmission of synapses---LTP, so that to verify the hypothesis that electroacupucture could improve depression-like behaviors through repairing synaptic plasticity in hippocampus of depression model rats.MethodsWistar rats were served as control group, Wistar Kyoto rats as depression model rats and were randomly divided into three groups in this research: model group, EA group, sham group. Each group included10rats. Control group and model group were non-interference. EA treatment was given once a day,15min, for3weeks. Two acupoints, GV20(Baihui) and EX-HN3(Yintang), were selected. EA frequency was held constant at2Hz (2pulses/second), the intensity was begun from0.1mA and adjusted according to the tolerance of rats, with the manifestation of nodding head gently. Sham group was received a placebo treatment. The depression-like behaviors were evaluated by sucrose water preference test, open field test (OFT), forced swim test (FST) after three weeks’ intervention. Long-term potentiation (LTP) evoked at Schaffer collateral-CAl synapses in hippocampal slices in vitro and synaptic struction was observed using transmission electron microscope.The expression of hippocampal AMPA and NMDA receptor subunits were detected by western blot. Results1、EA treatment can improve depression-like behavior in WKY rats. The percentage of sucrose intake was enhanced in EA group, while model group and sham group had less preference in sucrose preference test and showed significant differences with Control group(P<0.05). In OFT, central time, central activities, total time, total activities and rearing times were increased in EA group but not sham group. EA treatment also decreased immobility time in FST, while rats in model group and sham group showed significantly increased than wistar rats (P<0.05)2、The histological morphology of neuron and synapses in hippocampus of wistar rats was normal, the number of synapses was more than other groups. The hippocampal synaptic structure in WKY rats was damaged, EA treatment can repair the damage of synaptic structure.3、LTP was induced by tetanic stimuli at100Hz for1s in hippocampal Schaffer collateral-CA1in WKY rats. The hippocampal synaptic transmission efficiency in WKY rats was impaired. LTP can not be induced in hippocampal in model group and sham group rats, but it can be induced after EA treatment.4、NR2B expression was significantly increased in hippocampus after EA treatment compared with model group and sham group. But no significant differences in GluRl, GluR2, NR1, NR2A.ConclusionThe improvement of depression-like behavior in WKY depression model rats may relate to the increased NMDA receptor subunit NR2B expression and the modified synaptic structure in hippocampus after EA treatment.