[Effect of electroacupuncture on blood-brain barrier and central inflammatory response in obese rats]

To observe the effect of electroacupuncture (EA) on central nervous inflammatory response in obese rats, so as to explore its mechanisms underlying improvement of obesity.

Male SD rats were randomly allocated to normal control, model, EA and sham-EA groups (n=15/group). Rats of the normal group were fed with normal diet, and the obesity model was established by feeding the rats with high-fat diet for 8 weeks. EA (2 Hz, 1 mA) was applied to "Zusanli"(ST36), "Zhongwan"(CV12), "Guanyuan"(CV4) and "Fenglong"(ST40), and non-acupuncture points (about 5 mm left to CV4 and CV12 and about 5 mm lateral to ST36 and ST40) for 15 min, once every other day, 3 times a week for 8 weeks (no electrical current was delivered to the non-acupoints). The body weight and anal-nose length in each group were recorded before and after the intervention and Lee's index was calculated. The adipocyte morphology of epididymis was detected after H.E. staining, and the contents of serum tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-10 and free fatty acid (NEFA) were detected by using enzyme-linked immunosorbent assay (ELISA). The expression levels of TNF-α, IL-6, IL-10 and inducible nitric oxide synthase (iNOS) proteins in the hypothalamus tissue were detected by Western blot, and the immunoactivity of ionized calcium-binding adapter molecule 1 (Iba-1) in hypothalamic microglia was detected by immunohistochemistry. The content of Evans blue in the brain tissue samples was detected by Evans blue assay to evaluate the integrality of blood-brain barrier.

Compared with the normal group, the body mass (BM), Lee's index, contents of serum TNF-α, IL-6 and NEFA, expression levels of hypothalamic TNF-α, IL-6 and iNOS proteins, the immunoactivity level of Iba-1 and the content of Evans blue were significantly increased (P<0.01, P<0.05), while the content of serum IL-10 and the expression of hypothalamic IL-10 protein considerably decreased (P<0.01) in the model group. After the intervention, modeling induced increase of BM, Lee's index, contents of serum TNF-α, IL-6 and NEFA, expression levels of hypothalamic TNF-α, IL-6 and iNOS proteins, the immunoactivity level of Iba-1 and the content of Evans blue, and decrease of serum content and expression level of IL-10 in the hypothalamus were reversed by EA stimulation (P<0.01, P<0.05) but not by non-acupoint stimulation. H.E. staining showed that the adipocytes of epididymis became larger in size and decreased in the number in the model group relevant to the normal group, and became smaller after EA (not non-acupoint) relevant to the model group.

EA can treat obesity, improve body inflammation caused by obesity, and relieve central inflammation by repairing the blood-brain barrier.