title: Anxiety increases acid-induced esophageal hyperalgesia.
abstract: OBJECTIVE
  Anxiety at the time of gastrointestinal injury or inflammation increases the risk of developing visceral hyperalgesia. Distal esophageal acidification induces hyperalgesia in the non-acid exposed proximal esophagus, due to the sensitization of spinal dorsal horn neurones. The objective was to determine whether anxiety influences acid-induced hyperalgesia.
  
  
  METHODS
  A total of 19 healthy volunteers (n = 12 females; age, 22-57 years; mean, 35.7 years) completed a 10-minute mood induction paradigm (anxiety or neutral) with autonomic monitoring (visit 1). On visits 2 and 3, pain thresholds to electrical stimulation, in milliamperes (mA), were determined in the proximal esophagus and foot (control) before and after a 30-minute infusion of 0.15 M of hydrochloric acid. During esophageal acid infusion, the subjects randomly received anxiety or neutral mood induction with autonomic monitoring, in a crossover design. Anxiety and pain ratings were recorded pre and post infusion.
  
  
  RESULTS
  Visit 1: Anxiety induction increased anxiety scores (p < .001), mean arterial pressure (p < .001), and cardiac sympathetic index (p = .007), and reduced parasympathetic measures (cardiac vagal tone [p = .05] and cardiac sensitivity to baroreflex [p = .006)]). Visit 2: Anxiety induction conferred greater acid-induced hyperalgesia compared with neutral (-4.9 mA versus 2.7 mA, p = .009, analysis of covariance). No differences in autonomic measures were found during acid infusion with anxiety or neutral mood induction.
  
  
  CONCLUSIONS
  Anxiety induction increases acid-induced esophageal hyperalgesia; anxiety, thus, facilitates central sensitization in the esophagus. Our studies provide a new model for studying the effects of anxiety on esophageal hyperalgesia and may allow testing of therapeutic strategies to reduce this effect.
authors.affiliation: Salford Royal NHS Foundation Trust, Salford, United Kingdom.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Sharma
authors.forename: Lukas
authors.initials: L
authors.lastname: Van Oudenhove
authors.forename: Peter
authors.initials: P
authors.lastname: Paine
authors.forename: Lloyd
authors.initials: L
authors.lastname: Gregory
authors.forename: Qasim
authors.initials: Q
authors.lastname: Aziz
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects / Q000502:physiology; D001007:Anxiety / Q000150:complications / Q000453:epidemiology*; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D004935:Esophageal Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000209:etiology; D004947:Esophagus / Q000187:drug effects* / Q000294:innervation*; D005260:Female; D005764:Gastroesophageal Reflux; D006801:Humans; D006851:Hydrochloric Acid / Q000008:administration & dosage / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D006930:Hyperalgesia / Q000139:chemically induced* / Q000175:diagnosis / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000139:chemically induced* / Q000175:diagnosis; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology
chemical_list: D006851:Hydrochloric Acid