Effects and possible mechanisms of Acupuncture at ST36 on upper and lower abdominal symptoms induced by rectal distension in healthy volunteers
Background Acupuncture (AP) has been shown to have a therapeutic potential for gastrointestinal motility disorders. The aims of this study were to investigate the effects and possible mechanisms of acupuncture on postprandial upper and lower abdominal symptoms induced by rectal distension (RD). Methods: Twelve healthy volunteers were involved in a two-session study (AP and sham-AP). RD was performed for 60 min in the postprandial state and AP at ST36 or sham-AP was performed during the second 30-min period of RD. Gastric slow waves and heart rate variability (HRV) were recorded using the electrogastrogram and electrocardiogram, respectively. Upper and lower abdominal symptoms were scored during RD with AP/sham-AP. In five of the subjects, an additional experiment with two sessions (with AP and no-AP) was performed. Results: 1) RD at an average volume of 171ml induced upper and lower abdominal symptoms (p<0.01). AP but not sham-AP or no-AP reduced both upper and lower abdominal symptoms (p<0.05). 2) RD decreased the percentage of normal gastric slow waves p<0.05). AP improved gastric slow waves in comparison with sham-AP or no-AP (p<0.05). 3) AP but not sham-AP or no-AP significantly increased the vagal activity assessed by the spectral analysis of the HRV (p<0.05). Conclusions: RD induces upper or lower abdominal symptoms and impairs gastric slow waves in healthy volunteers. AP at ST36 is able to improve upper and lower abdominal symptoms and impaired gastric slow waves induced by RD, possibly mediated via the vagal pathway.