Muscarinic Receptor-Mediated Electroacupuncture Modulation of Reactive Enteric Glial Cells Ameliorates Postoperative Ileus.

Background: Emerging evidence highlights reactive enteric glial cells (EGCs) as pivotal players in the pathogenesis of postoperative ileus (POI). Recent studies have demonstrated that electroacupuncture (EA) Zusanli acupoint (ST 36) effectively alleviates POI. This study aims to investigate the underlying mechanisms of EA ST 36-mediated functional restoration of POI. Methods: A standardized intestinal manipulation (IM) procedure was conducted to establish the POI murine model. Mice were then treated with EA ST 36, and gastrointestinal (GI) motility function was measured after 24 hours. Immunofluorescence, Western blot, and hematoxylin-eosin staining were used to assess intestinal inflammation, the expression of glial fibrillary acidic protein (GFAP) and type 3 muscarinic acetylcholine receptors (m3AChRs). Vagus nerve activity was evaluated through plasma enzyme-linked immunosorbent assay combined with heart rate variability. Results: Compared to the Sham group, animals in the IM group demonstrated GI dysfunction characterized by delayed whole gut transit, prolonged colonic bead expulsion time, and reduced heart rate variability, which accompanied by decreased acetylcholine levels, elevated Chiu's scores, upregulated GFAP expression, and downregulated m3AChRs expression. EA ST 36 effectively mitigated these changes and enhanced c-Fos protein expression in the nucleus tractus solitarius. Fluorocitrate (a glial cell inhibitor) and carbachol (a cholinergic agonist) replicated the effects of EA ST 36, which was abolished by either pretreatment with J104129 (a specific m3AChR antagonist) or surgical vagotomy. Conclusion: The results suggest that EA ST 36 exerts its effects through vagally-mediated modulation of m3AChR signaling, which involves the reduction of the reactivity of EGCs and the improvement of GI dysfunction induced by IM.