Electroacupuncture improves cognitive dysfunction in rats with Alzheimer's disease by regulating microglial cells.

Objectives: To observe the effect of electroacupuncture (EA) on microglia (MG), Janus kinase-2 (JAK2) and signal transducer and activator of transcription-3 (STAT3) in hippocampal CA1 region of Alzheimer's di-sease (AD) rats, so as to explore its mechanisms in the treatment of AD.

Methods: Thirty-six male SD rats were randomly divided into sham operation, model and EA groups, with 12 rats in each group. The AD rat model was established by intraperitoneal injection of D-galactose combined with intrahippocampal injection of aggregated Aβ. The rats in the EA group were given EA (2 Hz/20 Hz, 2 mA) at "Baihui"(GV20) and"Shenting"(GV24) for 30 min, once daily, 6 days a week for 4 weeks. Morris water maze test was used to detect the learning and memory ability and spatial exploration ability of rats. HE staining was used to observe the pathological changes of hippocampus. The ultrastructure of hippocampal neurons was observed by transmission electron microscopy. The positive expression of MG marker io-nized calcium adaptor protein (Iba-1) in hippocampus was observed by immunofluorescence staining. The expression levels of serum inflammatory factor interferon-γ (IFN-γ) and transforming growth factor beta 1 (TGF-β1) were detected by ELISA. The mRNA expression levels of JAK2, STAT3, inducible nitric oxide synthase (iNOS) and arginase-1 (Arg-1) in hippocampal CA1 region were detected by real-time quantitative PCR. The protein and phosphorylation levels of JAK2 and STAT3 in hippocampal CA1 region were detected by Western blot.

Results: Compared with the sham operation group, the escape latency of the model group was significantly prolonged (<0.01), and the number of crossing the original platform was significantly reduced (0.01), the positive expression of Iba-1 in CA1 region, the content of serum IFN-γ, the relative mRNA expressions of JAK2, STAT3 and iNOS, and the protein and phosphorylation levels of JAK2 and STAT3 were significantly increased (<0.01), while the content of serum TGF-β1 and the relative expression of Arg-1 mRNA were significantly decreased (<0.01). Compared with the model group, the escape latency of rats in the EA group was significantly shortened (<0.01), the number of crossing the original platform was significantly increased (<0.01), the positive expression of Iba1, the content of serum IFN-γ, the mRNA expressions of JAK2, STAT3 and iNOS, and the protein and phosphorylation levels of JAK2 and STAT3 were significantly decreased (<0.05, <0.01), while the content of serum TGF-β1 and the expression of Arg-1 mRNA were significantly increased (<0.01). Moreover, pathological and ultrastructural observation showed a reduction in the number of hippocampal neurons, changement of nuclear morphology, dilation of intercellular space, and decreased number of mitochondria in the model group；these situations were relatively milder in the EA group.

Conclusions: EA can improve the learning and memory function of AD rats, which may be associated with its functions in decreasing MG activities, and inhibiting the JAK2 / STAT3 signaling pathway in the hippocampus.