The Autonomic Nervous System in Acupuncture for Gastrointestinal Dysmotility: From Anatomical Insights to Clinical...

The expanding knowledge on the involvement of the autonomic nervous system in regulating digestive tract homeostasis is shedding new light on the therapeutic potential of acupuncture. This review aims to evaluate the effectiveness and autonomic nervous system associated mechanisms of acupuncture in gastrointestinal dysmotility in both laboratory and clinical settings, guiding future studies. Mechanistically, studies with animal models and human subjects demonstrated that acupuncture, as a non-invasive somatosensory stimulation, can help improve gastrointestinal dysmotility via directly modulating the activation of autonomic nervous system. Additionally, acupuncture has been found to suppress inflammatory response and alter the secretion of gastrointestinal hormones via different somatic autonomic reflex pathways. Importantly, the therapeutic effects of acupuncture are affected by, and even rely on, the selected acupoints, the frequency and intensity of stimulation, type of gastrointestinal disorders, and the treatment frequency. Meanwhile, clinical studies indicated that acupuncture shows promise in alleviating gastrointestinal dysmotility from the esophagus to the colon, including conditions like gastroparesis, functional dyspepsia, postoperative ileus, irritable bowel syndrome, and chronic functional constipation. We argued against a narrow classification of abdominal and hindlimb acupoints as solely activating sympathetic or vagal nerve to decrease or increase gastrointestinal motility, respectively. Lastly, incorporating new technologies will assist to reveal central autonomic network changes in response to acupuncture stimulation.