Gamma-aminobutyric acid receptor type B agonist baclofen inhibits acid-induced excitation of secondary peristalsis but not heartburn sensation.

BACKGROUND AND AIM: Acute esophageal acid infusion promotes distension-induced secondary peristalsis. The gamma-aminobutyric acid receptor type B (GABA-B) receptors activation inhibits secondary peristalsis. This study aimed to test the hypothesis whether acid excitation of secondary peristalsis can be influenced by baclofen.

METHODS

Secondary peristalsis was performed with intra-esophageal slow and rapid air injections in 13 healthy subjects. Direct esophageal infusion of 0.1 N HCl following pretreatment with placebo or baclofen was randomly performed at least 1 week apart. Symptom intensity, distension thresholds, and peristaltic parameters were determined and compared between each study protocol.

RESULTS

The intensity of heartburn symptom in response to esophageal acid infusion was significantly greater with baclofen than the placebo (P = 0.002). The threshold volume of secondary peristalsis during slow air injections in response to acid infusion was significantly greater with baclofen than the placebo (P = 0.001). Baclofen significantly increased the threshold volume of secondary peristalsis during rapid air injections in response to acid infusion (P = 0.001). The frequency of secondary peristalsis in response to acid infusion was significantly decreased by baclofen as compared with the placebo (P = 0.001). Baclofen significantly decreased peristaltic amplitudes in response to acid infusion during rapid air injections (P = 0.007).

CONCLUSIONS

Gamma-aminobutyric acid receptor type B agonist baclofen inhibits acid excitation of secondary peristalsis in human esophagus, which is probably mediated by both muscular and mucosal mechanoreceptors. This work supports the evidence of potential involvement of GABA-B receptors in negative modulation of acid excitation of esophageal perception as well as secondary peristalsis.