Inhibition of transient lower esophageal sphincter relaxations by electrical acupoint stimulation

Abstract

Acupuncture has been shown to modulate visceral sensation and function. Traditionally, stimulation at the Neiguan (pericardial meridian) has been used to treat upper gastrointestinal symptoms. Some of the effects of acupuncture may be mediated through release of endogenous opioids and are reversed by naloxone. Gastric distension is the major trigger for transient lower esophageal sphincter (LES) relaxations (TLESRs). The aim of this study was to investigate the effect of electric stimulation at the Neiguan and naloxone on the TLESRs. In 14 healthy volunteers, electrical acupoint stimulation was applied at the Neiguan and a sham point on the hip in randomized order on the same day. In 12 healthy volunteers, the effects of naloxone (80 microg/kg iv bolus injection) and saline on electrical acupoint stimulation were compared on separate days at least 1 wk apart. Esophageal motility was measured during distension of the proximal stomach with 500 ml of air using a barostat balloon. Electric acupoint stimulation at the Neiguan decreased the rate of TLESRs by approximately 40% from a median of 6/h to 3.5/h (P < 0.02). Acupoint stimulation had no effect on basal LES pressure, the residual LES pressure during TLESRs, the duration of TLESRs, or gastrointestinal symptoms of fullness, bloating, discomfort, or nausea. The effect of acupoint stimulation was not inhibited by naloxone. Electric acupoint stimulation at the Neiguan significantly inhibits the frequency of TLESRs in response to gastric distention in healthy subjects. This effect does not appear to be mediated through mu-opioid receptors.

Effects and mechanisms of electroacupuncture at PC6 on frequency of transient lower esophageal sphincter relaxation in cats

“…Transcutaneous electric nerve stimulation (TENS) at Hukou acupoint increased the degree of LES relaxation in volunteers [13] and reduced basal LES pressure in patients with achalasia [14,15] . Previous studies have suggested that TENS at neiguan may inhibit the rate of TLESRs triggered by gastric distention [16] and reduce the perception to gastric distention [17] in human beings. But the precise mechanisms for this phenomenon have not been extensively investigated and are not fully understood.…”

Gastrointestinal Motility Disorders: An Update

“…Finally, electrical acupoint stimulation was recently evaluated to determine its effect on TLESRs in a study of 14 healthy volunteers [54] . Electric acupoint stimulation inhibited the frequency of TLESRs compared to sham stimulation, although it did not change LES pressure, esophageal motility, or the duration of TLESRs.…”

Comparing the Effects of Acupuncture and Pharmacologic Therapies on Delayed Gastric Emptying: A Prospective, Block-Randomized, Single-Blinded, Parallel Clinical Trial

“…Zou et al showed that acupuncture in healthy patients that is followed by a reduction in the frequency of repeated lower esophagus esphincter relaxation is probably caused by the stimulation of the efferent vagus nerve (31). However, some studies have examined and reported positive acupuncture effects on gastric movement and acid secretion in animal models (32).…”