Mechanism Research Progress of Acupuncture Regulating Vagus Nerve-Cholinergic Anti-inflammatory Pathway in the Prevention and Treatment of Endometriosis-Related Pain

Endometriosis (EM)-related pain involves multiple links including local inflammatory microenvironment, neurogenic inflammation, peripheral and central sensitization, and autonomic nervous imbalance. Current hormone therapy and surgical treatment cannot achieve sufficient pain relief and are prone to recurrence. This paper reviews the role of the vagus nerve-mediated cholinergic anti-inflammatory pathway (CAIP) in EM pain and the mechanistic evidence that acupuncture regulates this pathway. It proposes that CAIP impairment in EM may exist at two levels simultaneously: reduced central vagal efferent tone and downregulated expression of local α7 nicotinic acetylcholine receptor (α7nAChR) in peripheral lesions. Patients with EM have decreased vagal tone which correlates with pain severity. Vagus nerve stimulation can slow lesion progression and improve hyperalgesia in animal models, and α7nAChR agonists can inhibit lesion formation and fibrosis. Electroacupuncture activates the vagus-adrenal axis or spleen-dependent CAIP via acupoints such as Zusanli to exert anti-inflammatory effects, with selectivity for acupoints and stimulation parameters. It is thus inferred that simply enhancing upstream vagal input may be inadequate. Combined strategies that raise vagal efferent tone while improving local receptor reactivity in lesions deserve exploration. Future work shall optimize acupuncture parameters using dedicated EM models and design rigorous clinical trials for mechanistic verification.