Effects of acupuncture on regulating the hippocampal inflammatory response in rats exposed to post-traumatic stress disorder

Abstract

Data from clinical and experimental studies have verified the efficacy and safety of acupuncture in the treatment of post-traumatic stress disorder (PTSD). However, the concrete mechanism has not been well elucidated. The stress-induced activation of inflammatory response is involved in the development and pathogenesis of PTSD. Here, we aimed to investigate the effects of acupuncture on regulating the hippocampal inflammatory response in rats exposed to PTSD. Forty male rats were randomly divided into control, model, acupuncture and sertraline group. Within 1 day after adaptive feeding, all rats were exposed to single prolonged stress (SPS), except for the rats in the control group. Rats in acupuncture group were exposed to acupuncture intervention at the acupoints of Baihui (GV20) and Yintang (GV29), 20 min once per day for 15 days. Rats in sertraline group were exposed to a suspension of sertraline and distilled water (0.2 mg/ml), once per day for 15 days continuously. Body weight and elevated plus maze experiment were detected at different time-points to evaluate the behavioral changes of rats. HE staining method was used to observe the basic pathological morphological changes in hippocampus. Immunofluorescence staining method was used to observe the activation of hippocampal microglia. The content of IL-6 and IL-1β in serum were detected by ELISA method. Compared with the control group, the body weight of rats in model group significantly decreased on 8 days, and the percentage of time in open arms and open arm entries decreased significantly on 15 days after SPS procedures, which indicated that SPS induced PTSD-like behavior in rats. Acupuncture exerted therapeutic effect. Simultaneously, the result of HE staining confirmed that SPS induced hippocampal morphological changes in SPS rats. Notably, acupuncture reversed the reduction and pathological injury to some extent. The results have also shown that acupuncture intervention effectively reversed the activated microglia of the hippocampus in rats. Moreover, the expression of IL-1β in serum was significantly decreased by acupuncture intervention. In summary, the present study demonstrated that the role of acupuncture in eliminating PTSD-like behavior might be connected with reversing the pathological process of the inflammatory response mediated by the activation of microglia induced by SPS.