Effects of electroacupuncture on perioperative neurocognitive impairment and gut-associated Th17/Treg balance in aged rats

BACKGROUND: Perioperative neurocognitive disorder (PND) occurs most frequently in elderly populations undergoing surgery and anesthesia. Evidence suggests that gut-initiated helper T (Th)17/regulatory T (Treg) cell immune responses are involved in the pathogenesis of neurocognitive disorders, and electroacupuncture (EA) has been shown to be effective at regulating Th17/Treg cell balance and ameliorating cognitive dysfunction. The aim of this study was to investigate whether EA ameliorates PND via the regulation of gut-initiated Th17/Treg immune balance in a rat model. METHODS: Exploratory laparotomy was performed in aged rats to establish a PND model, and EA at ST36 and ST37 was administered daily for 5 days before surgery. Neurocognitive function was evaluated using the Morris water maze test. Colonic mucosa and hippocampal neurons were observed under hematoxylin and eosin (H&E) staining. Ionized calcium-binding adapter molecule (Iba)1, a hippocampal microglia marker, was observed by immunohistochemistry. Proportions of Th17 and Treg cells in mesenteric lymph nodes (MLNs) and blood were examined by flow cytometry. Western blotting was used to detect the protein expression of retinoid-related orphan receptor (ROR)γt and forkhead box (Fox)p3 in the colon and hippocampus. Levels of interleukin (IL)-17A and IL-10 in the blood and hippocampus were examined by enzyme-linked immunosorbent assay. RESULTS: EA pretreatment improved surgery-induced neurocognitive impairment. Meanwhile, EA inhibited colonic mucosal injury, neuronal damage and microglial activation in PND rats. EA also decreased Th17 cells in the MLN and blood, RORγt in the colon and hippocampus, and IL-17A in the blood and hippocampus of PND rats. EA reversed downregulation of Treg cells in the MLN, Foxp3 in the colon and hippocampus, and IL-10 in the blood and hippocampus of PND rats. CONCLUSION: Collectively, the results suggest that the therapeutic benefits of EA pretreatment in this PND rat model may be attributable to the regulation of gut-associated Th17/Treg immune balance.