Effect of “Tongdu Qishen” acupuncture on pyroptosis in hippocampus and cortex of SAMP8 mice

To explore the underlying mechanism of “Tongdu Qishen” acupuncture (dredging the Govern Vessel and normalizing mental activities) in treating SAMP8 mice from the perspective of pyroptosis.

Six-month-old male SAMP8 mice were randomly divided into model and “Tongdu Qishen” acupuncture (EA) groups, with 12 mice in each group. SAMR1 mice of the same age (n=12) were used as the normal group. In the EA group, EA (2 Hz/50 Hz, 20 min) was applied to “Baihui”(GV20) and “Yintang”(GV24⁺), and pricking bleeding was applied to “Shuigou”(GV26). The treatment was performed once a day, for a total of 28 days. Morris water maze test was used to evaluate the learning and memory ability of mice, and HE staining was used to observe the morphology of cells in the hippocampus and cortex. Nissl staining was used to observe the number of neurons in the hippocampus and cortex. Immunohistochemistry was used to observe the expressions of Aβ_1-40, interleukin (IL)-1β and IL-18 in the hippocampus and cortex. The co-staining of TUNEL and Caspase-1 was detected by immunofluorescence. Western blot and real-time quantitative PCR were used to observe the protein and mRNA expression levels of Nod-like receptor 3(NLRP3), Caspase-1 and Gasdermin D (GSDMD) in the hippocampus and cortex, respectively.

Behavioral results showed that compared with the normal group, the escape latency was prolonged (P＜0.001), the dwell time in the original platform quadrant and the times of crossing the original platform were considerably decreased (P＜0.001) in the model group. In comparison with the model group, the escape latency was shortened (P＜0.05, P＜0.001, P＜0.01), and the dwell time in the original platform quadrant was significantly increased (P＜0.01) in the EA group. Following modeling, the number of neurons was decreased (P＜0.001), the positive expression of Aβ_1-40, IL-1β and IL-18 in the hippocampus and cortex, the co-expression of TUNEL and Caspase-1, and the protein and mRNA expression levels of NLRP3, Caspase-1, GSDMD were all increased (P＜0.001) in the model group relevant to the normal group. After EA intervention, modeling induced increase and decrease of indexes mentioned above were completely reversed (P＜0.01,P＜0.05,P＜0.001).

“Tongdu Qishen” acupuncture may improve the cognitive function of SAMP8 mice by regulating the NLRP3/Caspase-1/GSDMD pathway, relieving the release of inflammatory factors and reducing the content of Aβ_1-40.