DIFFERENTIAL-EFFECTS OF AMITRIPTYLINE ON PERCEPTION OF SOMATIC AND VISCERAL STIMULATION IN HEALTHY HUMANS

Tricyclic antidepressants treat chronic pain both in patients with som atic illness and with functional bowel disorders. We compared the effe cts of amitriptyline on perception of cutaneous and gastrointestinal s timulation to assess differential analgesic effects of tricyclics on s omatic and visceral pain. Cutaneous electrical stimulation and rectal and esophageal distension were performed before and after 21 days of d ouble-blind 50 mg amitriptyline vs. placebo in healthy volunteers. Ami triptyline increased currents that elicited cutaneous threshold, moder ate discomfort, and moderate pain compared with basal (P < 0.05), wher eas placebo had no effect. Amitriptyline had no effect on perception o f rectal and esophageal distension and did not alter luminal complianc e; thus the lack of effect on perception is not due to altered viscera l elastic wall properties. In conclusion, amitriptyline reduces percep tion of cutaneous stimulation but does not alter visceral perception o r compliance. This investigation demonstrates differential effects of tricyclics on somatic and visceral afferent function in healthy humans and provides insight into mechanisms of action in chronic pain both f rom somatic disease and from functional bowel disorders.