Amitriptyline modifies the visceral hypersensitivity response to acute stress in the irritable bowel syndrome.
BACKGROUND
Acute physical stress causes alteration in gut autonomic function and visceral hypersensitivity in patients with irritable bowel syndrome (IBS). We have developed a model to measure this stress response.


OBJECTIVE
To assess whether treatment with a drug effective in treating IBS (amitriptyline) alters the response to acute stress in IBS patients.


METHODS
Nineteen patients with IBS were given amitriptyline 25-50 mg. Patients underwent physical stress (cold pressor) test at baseline and after 3 months of treatment. Physiological parameters measured were: stress perception; systemic autonomic tone [heart rate (HR) and blood pressure (BP)]; gut specific autonomic innervation [rectal mucosal blood flow (RMBF)] and visceral sensitivity (rectal electrosensitivity).


RESULTS
Fourteen of 19 (74%) patients improved symptomatically after 3 months of amitriptyline. Acute stress induced increased perception of stress and systemic autonomic tone and reduced RMBF in symptomatic responders and nonresponders (P > 0.05 for all). All nonresponders but only 3 of 14 responders continued to exhibit stress-induced reduced pain threshold at 3 months (change from baseline -31% vs. +2%, P < 0.03 respectively).


CONCLUSIONS
In this open study, amitriptyline appears to decrease stress-induced electrical hypersensitivity; this effect is independent of autonomic tone. The gut response to acute stress deserves further study as a model to study drug efficacy in IBS.
Thoua
N M
NM
GI Physiology Unit, University College Hospital, London, UK.
Murray
C D R
CD
Winchester
W J
WJ
Roy
A J
AJ
Pitcher
M C L
MC
Kamm
M A
MA
Emmanuel
A V
AV
D000328:Adult; D000639:Amitriptyline / Q000627:therapeutic use*; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000188:drug therapy* / Q000503:physiopathology; D043183:Irritable Bowel Syndrome / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D012007:Rectum / Q000187:drug effects* / Q000503:physiopathology; D013223:Statistics as Topic; D014781:Viscera / Q000187:drug effects* / Q000503:physiopathology; D055815:Young Adult
D018712:Analgesics, Non-Narcotic; D000639:Amitriptyline