Effects of electroacupuncture preconditioning on microglial cells and serum inflammatory factors in the early stage of ischemic stroke.

Objectives: To investigate the effects on the motor function, cortex blood flow perfusion, microglial cells, and the contents of serum inflammatory factors, i.e. interleukin-1β (IL-1β), transforming growth factor-β (TGF-β), and interleukin-10 (IL-10) after electroacupuncture (EA) preconditioning at "Baihui" (GV20) and "Dazhui" (GV14) in the mice with ischemic stroke, so as to explore the mechanism of EA preconditioning for improving motor function after ischemic stroke.

Methods: C57BL/6 mice were randomly divided into sham-operation group, model group, and EA preconditioning group (EA group), with 15 mice in each group. A photothrombotic method was used to induce the model of unilateral ischemic stroke and motor impairment. The mice in the EA group received EA preconditioning, 20 min each time, once daily for 7 consecutive days before modeling. The motor function of mice was evaluated by the grid-walking test and cylinder test before and after modeling. Laser speckle blood flow video monitoring system was employed to assess the cerebral blood flow perfusion in the primary motor cortex of mice. The contents of IL-1β, TGF-β, and IL-10 in the serum were measured by ELISA, and the expressions of microglial cell and M2 subtype cell marker in the primary motor cortex were detected using immunofluorescence staining.

Results: After modeling, compared with the sham-operation group, the grid error rate and the dragging rate of the affected limb were increased (<0.01)；the utilization rate of the affected limb and percentage of the blood perfusion in the affected cortex to healthy side were decreased (<0.01)；the contents of serum IL-1β, TGF-β, and IL-10 were increased (<0.01, <0.05)；and the microglia in the primary motor cortex on the affected side showed ameboid, the fluorescence intensity of ionized calcium-binding adapter molecule 1 (IBA1) and CD206 was increased (<0.01) in the model group. In the EA group, when compared with the model group, the grid error rate and the dragging rate of affected limb were decreased (<0.01)；the utilization rate of affected limb and the percentage of blood perfusion were increased (<0.05)；the content of serum IL-1β was decreased (<0.01), while the contents of TGF-β and IL-10 were increased (<0.01)；and the microglia in the primary motor cortex on the affected side got more round and were distributed more densely, the fluorescence intensity of IBA1 and CD206 was increased (<0.01).

Conclusions: Electroacupuncture preconditioning at "GV20" and "GV14" can up-regulate the expression of microglial cells, especially the M2 subtype cell marker, and increase the contents of the anti-inflammatory factors and decrease that of the pro-inflammatory factors in the serum, thereby alleviate the inflammatory reaction.