[Electroacupuncture of scalp acupoints alleviates neurological deficits by regulating PPAR γ/NF-κB signaling pathway and inducing polarization of microglia in rats with ischemic stroke].

OBJECTIVES

To observe the effect of electroacupuncture (EA) of scalp acupoints on peroxisome proliferator-activated receptor γ (PPARγ), phosphorylated nuclear factor kappa-B p65 (p-NF-κB p65), interleukin (IL)-1β and IL-4 as well as CD16 and CD206 in the ischemic cortical tissues of rats with ischemic stroke (IS), so as to explore its mechanisms underlying alleviation of inflammatory damage in ischemic stroke.

METHODS

Male SD rats were randomly assigned to sham surgery, model, EA, and EA+ inhibitor groups, with 12 rats in each group. The IS model was established by occlusion of the middle cerebral artery with suture-embolus in reference with the modified Zea-Longa method. EA (2 Hz/ 100 Hz, 1 mA) was applied to bilateral "Dingnie Qianxiexian" (MS6) for 30 min, once a day for 7 consecutive days. Rats of the EA+inhibitor group received intraperitoneal injection of GW9662 solution (10 mg/mL, an inhibitor of PPARγ). The neurological deficit severity (0-3 points) was assessed using Zea-Longa score, modified neurological severity score (mNSS) and neurobehavioral score before and after the intervention. The cerebral infarction volume was determined using 2, 3, 5-triphenyltetrazolium chloride (TTC) staining, and the expression of IL-1β, IL-6, tumor necrosis factor-α (TNF-α), IL-4, IL-10, and transforming growth factor-β (TGF-β) in the ischemic cortex was detected using immunohistochemistry. The immunofluorescence double labeling of microglial markers CD16 and CD206 in the ischemic cortex was observed. Western blot was used to detect the expression of PPARγ, p-NF-κB p65, inducible nitric oxide synthase (iNOS), and arginase1 (ARG1) proteins in the ischemic cortex.

RESULTS

Compared with the sham surgery group, the Zea-Longa score, mNSS score and neurobehavioral score, cerebral infarction volume, and the expression levels of p-NF-κB p65, iNOS, the number of CD16/IBA1 double-labelled cells, and the immunoactivity of IL-1β, IL-6 and TNF-α were significantly increased (P<0.01), while the expression of PPARγ and ARG1 proteins, number of CD206/IBA1 double-labelled cells, and the immunoactivity of IL-4, IL-10 and TGF-β were significantly decreased (P<0.01) in the model group. After the intervention, in comparison with the model group, the Zea-Longa score, mNSS score and neurobehavioral score, the cerebral infarction volume, number of CD16/IBA1 double-labelled cells, and the immunoactivity of IL-1β, IL-6 and TNF-α, and the expression levels of p-NF-κB p65, iNOS, number of CD16/IBA1 double-labelled cells, and the immunoactivity of IL-1β, IL-6 and TNF-α were considerably decreased (P<0.01), whereas the expression levels of PPARγ and ARG1 proteins, the number of CD206/IBA1 double-labelled cells, and the immunoactivity of IL-4, IL-10 and TGF-β were strikingly increased (P<0.01) in the EA group. After administration of GW9662, the effects of EA were eliminated in reducing the Zea-Longa score, mNSS score and neurobehavioral score, in downregulating the expression of iNOS, p-NF-κB p65, IL-1β and TNF-α (P<0.01), and in upregulating the expression of ARG-1, PPARy, and IL-4, and the number of CD206/IBA1 double-labelled cells (P<0.01) in the EA+inhibitor group.

CONCLUSIONS

EA of MS6 can alleviate the degree of neurological deficit and reduce the volume of cerebral infarction in IS rats, which may be related to its functions in regulating the PPARγ/NF-κB signaling pathway and in promoting the transformation of microglia towards M2 phenotype.