Objective
The occurrence and development of atrial fibrillation (AF) are influenced by the autonomic nervous system and inflammation. Acupuncture is an effective treatment for AF. This study explored the protective effects of acupuncture in a rat model of paroxysmal AF and investigated its mechanisms.
Methods
Male Sprague-Dawley rats (n = 130) were randomly divided into blank control (Con), sham operation (Sham), AF, and acupuncture treatment (Acu) groups. A paroxysmal AF model was established by rapid atrial pacing through the jugular vein. Rats in the Acu group were immobilized to receive acupuncture treatment at Neiguan acupoint (PC6) for 20 min daily for seven days. The other groups were immobilized for the same duration over the treatment period but did not receive acupuncture. The AF induction rate, AF duration, cardiac electrophysiological parameters, and heart rate variability were evaluated by monitoring surface electrocardiogram and vagus nerve discharge signals. After the intervention, the rats were euthanized, and atrial morphology was assessed using haematoxylin and eosin staining. The expression of macrophage F4/80 antigen (F4/80) and cluster of differentiation (CD) 86 in atrial myocardial tissue was detected using immunohistochemistry, immunofluorescence and flow cytometry. The expression levels or contents of interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), α7 nicotinic acetylcholine receptor (α7nAChR), phosphorylated Janus kinase 2 (p-JAK2), and phosphorylated signal transducer and activator of transcription 3 (p-STAT3) in atrial myocardial tissue were detected using Western blotting, reverse transcription-quantitative polymerase chain reaction, or enzyme-linked immunosorbent assay. The role of α7nAChR in acupuncture treatment was verified by intraperitoneal injection of the α7nAChR antagonist methyllycaconitine (MLA).
Results
Compared with the AF group, acupuncture significantly reduced AF duration and induction rate, improved cardiac electrophysiology by enhancing vagus nerve activity and regulating autonomic balance. It also decreased the pro-inflammatory M1 macrophage proportion, alleviating myocardial injury and infiltration. MLA weakened acupuncture’s electrophysiological improvement and anti-inflammatory effect. Results suggest that acupuncture triggers the α7nAChR-JAK2/STAT3 pathway and exerts cardioprotection via neuroimmune regulation.
Conclusion
Acupuncture significantly reduced the AF induction rate, shortened AF duration, improved cardiac electrophysiological parameters, enhanced vagus nerve activity, and decreased the expression of pro-inflammatory M1 macrophages and inflammatory factors in rats with paroxysmal AF. Its positive effects are related to the activation of the α7nAChR-mediated JAK2/STAT3 signalling pathway, indicating that the interaction between cardiac vagus nerve and macrophages may be a potential target for acupuncture in the prevention and treatment of AF.

Key words: α7nAChR-JAK2/STAT3 signaling pathway, Acupuncture, Atrial fibrillation, Inflammation, Macrophages