Acupuncture and regulation of gastrointestinal function

This comprehensive review examines the therapeutic effects and underlying mechanisms of acupuncture in the treatment of gastrointestinal dysfunction, drawing on the analysis of 65 scientific articles published between 2005 and 2015. The study offers a systematic view of how acupuncture regulates four fundamental aspects of digestive function: gastrointestinal motility, intestinal barrier, visceral sensitivity, and the brain-gut axis. In traditional Chinese medicine, acupuncture has been used for more than 3,000 years to treat digestive disorders, but only recently have the scientific mechanisms begun to be understood. The research reveals that acupuncture has unique dual regulatory effects on gastrointestinal motility — it promotes gastric peristalsis in individuals with low baseline motility but suppresses peristalsis in cases of excessive motility.

This bidirectional regulatory effect supports the traditional Chinese medicine theory that acupuncture restores the balance between yin and yang. The most studied acupuncture points include Zusanli (ST-36), considered the classic point for digestive disorders, Neiguan (PC-6), Zhongwan (CV-12), Shangjuxu (ST-37), and Tianshu (ST-25). The mechanism of action of acupuncture on gastrointestinal motility primarily involves the nervous system, specifically the vagal and sympathetic pathways. Electroacupuncture at ST-36 increases gastric motility through the efferent parasympathetic pathway, while stimulation at CV-12 inhibits motility through the efferent sympathetic pathway.

Studies have demonstrated that these effects are intensity-dependent and mediated by TRPV1 receptors, NMDA receptors, and opioidergic pathways. Regarding the gastrointestinal barrier, acupuncture provides protection against mucosal injury through regulation of the neuro-endocrine-immune system. Electroacupuncture at ST-36 has demonstrated significant anti-inflammatory effects, preventing intestinal barrier and remote organ injury through activation of the cholinergic-dependent anti-inflammatory pathway. In addition, acupuncture protects the gastric mucosa by increasing the concentration of epidermal growth factor in gastric mucosal tissue and by modulating the expression of different isoforms of nitric oxide synthase.

For visceral sensitivity, particularly relevant in irritable bowel syndrome, acupuncture demonstrates significant antihyperalgesic effects. Electroacupuncture at ST-36 and ST-37 reduces chronic visceral hypersensitivity through multiple pathways, including the opioidergic, adrenergic, and serotonergic systems. The treatment modulates serotonin (5-HT) levels and its receptors and also affects the expression of NMDA receptors in the spinal cord. The brain-gut axis represents a particularly fascinating area of acupuncture research.

Functional neuroimaging studies demonstrate that manual acupuncture at ST-36 modulates neural activity at multiple levels of the cerebellar and limbic systems. Acupuncture influences the expression of brain-gut peptides, including substance P, vasoactive intestinal peptide, motilin, and cholecystokinin, which are important regulators of gastrointestinal motility. The study also reveals that acupuncture effects are specific to anatomical points — different acupoints produce distinct effects on gastrointestinal function. This specificity supports traditional Chinese medicine principles regarding the importance of precise point location in acupuncture therapy.

Identified limitations include the need for more systematic studies on acupoint selection and stimulation parameters, as well as deeper investigation of the mechanisms involving brain-gut peptides. Future research should incorporate optimized methodologies that consider both acupoint selection and stimulation parameters to maximize therapeutic benefits.