Preliminary report: modulation of parasympathetic nervous system tone influences oesophageal pain hypersensitivity

• Published in: Gut Vol. 64; no. 4; pp. 611 - 617
• Main Authors: Botha, Claude, Farmer, Adam D, Nilsson, Matias, Brock, Christina, Gavrila, Ana D, Drewes, Asbjørn Mohr, Knowles, Charles H, Aziz, Qasim
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd and British Society of Gastroenterology 01.04.2015; BMJ Publishing Group LTD
• Subjects: Abdominal Pain; Acidification; Adolescent; Adult; Anxiety; Atropine; Autonomic nervous system; Catheters; Conductance; Cross-Over Studies; Electrical stimuli; Electrodes; Esophagus; Female; Heart; Hospitals; Humans; Hydrochloric acid; Hypersensitivity; Male; Middle Aged; Nervous system; Neurogastroenterology; Pain; Pain - physiopathology; Pain Measurement; Pain perception; Parasympathetic nervous system; Parasympathetic Nervous System - physiology; Physiology; Placebos; Respiration; Skin; Skin conductance response; Vagus nerve; Visceral Hypersensitivity; Visceral Nociception; Visceral Sensitivity; Young Adult; United Kingdom > UK; Denmark; Abdominal Pain; Visceral Hypersensitivity; Visceral Nociception; Visceral Sensitivity
• ISSN: 0017-5749; 1468-3288; 1468-3288
• DOI: 10.1136/gutjnl-2013-306698

Objectives Autonomic nervous system dysfunction has been implicated in visceral hypersensitivity. However, the specific contribution of the parasympathetic nervous system (PNS) is unclear. We aimed to determine whether physiological and pharmacological manipulation of parasympathetic tone influences the development of hypersensitivity in a validated model of acid-induced oesophageal pain. Design Prior to, and following, a 30-min distal oesophageal infusion of 0.15 M hydrochloric acid, pain thresholds to electrical stimulation were determined in the proximal non-acid exposed oesophagus in healthy subjects. Validated sympathetic (skin conductance response) and parasympathetic (cardiac vagal tone) parameters were measured at baseline and continuously thereafter. In study 1, 55 subjects were randomised in a pragmatic blinded crossover design to receive deep breathing or un-paced breathing during acid infusion. In study 2, 32 subjects were randomised in a blinded, crossover design to receive intravenous atropine or placebo (saline) with deep breathing during acid infusion. Results Study 1: Deep breathing increased cardiac vagal tone (2.1±2.3 vs −0.3±2.3, p=0.0006) with concomitant withdrawal of skin conductance response (−0.6±4.9 vs 3±4.8, p=0.03) in comparison with un-paced breathing. Deep breathing prevented the development of acid-induced oesophageal hypersensitivity in comparison with sham breathing (p=0.0001). Study 2: Atropine, in comparison with placebo, blocked the attenuating effect of deep breathing on the development of acid-induced oesophageal hypersensitivity (p=0.046). Conclusions The development of oesophageal hyperalgesia is prevented by physiologically increasing parasympathetic tone. This effect is pharmacologically blocked with atropine, providing evidence that the PNS influences the development of oesophageal pain hypersensitivity.