[Electroacupuncture inhibits neuron injury of SAMP8 mice by reducing inflammatory response]

To observe the effect of electroacupuncture (EA) at "Baihui"(GV20) and "Shenshu" (BL23) on the pathological injury of neurons in SAMP8 mice and the anti-inflammatory effect on neuron repair, providing a new experimental basis for EA prevention and treatment of Alzheimer's disease.

Twelve 7-month-old SAMP8 mice were randomly divided into model and EA groups, and 6 SAMR1 mice of the same age and genetic background were used as normal group. Mice in the EA group were needled at GV20 and bilateral BL23, and EA (1 mA, 2 Hz) was applied to bilateral BL23 for 15 min, once daily, 10 d as a course for a total of 4 courses, with an interval of 1 d. Mice in the normal and model groups were captured and fixed in the same way as the EA group. The spatial learning and memory ability was detected by Morris water maze test. Neuronal nuclear antigen (NeuN) positive expression and the number of NeuN-positive cells in dentate gyrus (DG) were detected by immunofluorescence staining. The protein expression levels of ionized calcium binding adapter molecule 1(Iba-1), tumor necrosis factor-α(TNF-α), interleukin (IL)-6 and IL-1β in hippocampus were detected by Western blot. The ultrastructure of nerve cells in DG was observed by transmission electron microscopy.

Compared with the normal group, the average escape latency was prolonged(P<0.01), the number of platform crossing was significantly reduced (P<0.01), the average fluorescence intensity of NeuN and the number of NeuN-positive cells in hippocampus DG region decreased (P<0.05), the expression levels of Iba-1, TNF-α, IL-6 and IL-1β in hippocampus were increased (P<0.05) in the model group.Compared with the model group, the ave-rage escape latency was shortened (P<0.01), the number of platform crossing times was significantly increased (P<0.01), the average fluorescence intensity of NeuN and the number of NeuN-positive cells in hippocampus DG region increased (P<0.05), the expression levels of Iba-1, TNF-α, IL-6 and IL-1β in hippocampus were decreased (P<0.05) in the EA group. The morphology of nerve cells in the hippocampus DG region was normal， and the organelles in the cytoplasm were clear, complete and regularly distributed in the normal group. However, the morphology of nerve cells in the model group was seriously irregular, which was also irregular in EA group but somewhat relieved compared with model group.

EA at GV20 and BL23 can improve the learning and memory ability of SAMP8 mice, which may be related to inhibiting the neuroinflammatory response, increasing the number of neurons and improving the ultrastructure of the DG region of the hippocampus to play the role of neuron protection.