The Effect Of Electroacupuncture On The Behavioristics And Hippocampal INOS In CUMS Rat Model

Objective:To observe the impact of electroacupuncture on the behavioristics and hippocampal iNOS in chronic unpredictable mild stress (CUMS) rat model of depression.Methods:24 adult SD rats were randomly divided into control and modeling groups, with 10 and 24 in each, respectively. Rats in modeling group were raised separately and administrated with unpredictable mild stress of 21 days. We evaluated the depression-like behaviors of rats by open field test, and the successful model of rats were further randomly divided into model and electroacupuncture (EA) groups, with 10 in each. Rats in EA group were intervened by electroacupuncture every day. We performed with disposable acupuncture needles (Hwato brand, 0.35*13 mm) and Han’s electric acupuncture apparatus (HANS-200E). After horizontally inserting needles into Baihui (GV 20) and Yintang (EX-HN 3), we connected HANS-200E to the needles with a setting of 1.0 mA and 2 Hz. The treatment lasted for 15 min without any restraint. Both control and model groups were subjected to no disposal during the period. After 14 days treatment, the open field behavior and behavioristics of all three groups were tested, and later hippocampus levels of iNOS and nitrotyrosine were detected by western blotting and immunohistochemistry. Real-time reverse transcription PCR (RT-PCR) was used to determine the relative expression of iNOS mRNA in hippocampus among the groups.Results:1)Model group displayed significant decreased horizontal moving distance, upstanding times and central region-entering times in comparison with control group (P< 0.01), showing the rats of model group had obviously decreased motion activity and exploring desire, equal to depression-like behavior. The behavioral indicators of EA group were better than model group with a statistical difference (P< 0.01), and showed no obvious difference when compared with control group, indicating EA is capable of improving depression-like behavior.2)Both western blotting and immunohistochemistry showed high expression of hippocampal iNOS and nitrotyrosine in model group, which was significantly different from that in control group (P< 0.01). Compared with model group, the hippocampus levels of iNOS and nitrotyrosine in EA group were significantly decreased (P< 0.05), which were discrepant from control group though. RT-PCR displayed higher expression of iNOS mRNA in rat hippocampus in model group than control group, which was down-regulated to nearly normal levels in EA group, indicating CUMS rat model of depression underwent a pathological condition of high expression of iNOS and nitrotyrosine in hippocampus, intervention with EA could reduce hippocampal iNOS on the level of gene transcription and protein, and simultaneously down-regulate nitrotyrosine expression. Moreover, the same direction of changes in hippocampal iNOS and nitrotyrosine suggested the correlation between iNOS and (oxidative and nitrosative) stress.Conclusion:EA can improve the depression-like behavior of CUMS rat model, down-regulate high expression of hippocampal iNOS and nitrotyrosine induced by chronic stress and reduce (oxidative and nitrosative) stress in hippocampus. The down-regulation to abnormal changes of iNOS and (oxidative and nitrosative) stress in hippocampus may underlie one of internal mechanisms of the anti-depressive effects of EA. In CUMS rat model of depression and (oxidative and nitrosative) stress of hippocampus, iNOS may play a pivotal role.