Effect of repeated capsaicin ingestion on intestinal chemosensation and mechanosensation.
BACKGROUND
Ingestion of capsaicin reduces symptoms in functional dyspepsia but induces upper abdominal symptoms initially.


OBJECTIVE
To evaluate the effects of one week of oral dosing with capsaicin on mechanonociception and chemonociception.


METHODS
Healthy subjects ingested capsules containing 0.5 mg capsaicin t.d.s (n = 8) or placebo (n = 5) for 7 days. Before (day 0) and after (day 8) capsule ingestion the jejunum was distended with a balloon and perfused with a capsaicin solution. A graded questionnaire evaluated distension- and capsaicin-induced sensation, aggregate perception scores were calculated.


RESULTS
Infusion of capsaicin induced sensations similar to distension. In subjects receiving capsaicin capsules, mean +/- S.E.M. perception scores at 24 mL distension volumes were 4.7 +/- 1.2 (day 0) and 3.2 +/- 1.3 (day 8, N.S.). Distension with 40 mL induced perception scores of 10.3 +/- 1.0 vs. 8.2 +/- 1.0 (P < 0.05). During capsaicin perfusion, first sensation was reported after 13.2 +/- 1.9 min (day 0) and 8.1 +/- 0.8 min (day 8, N.S.), discomfort thresholds after 44.1 +/- 6.0 and 31.2 +/- 5.7 min (P < 0.05). In the placebo group, mechano- and chemonociception remained unaltered on days 0 and 8.


CONCLUSIONS
One week of ingestion of capsaicin sensitized chemonociceptors, while sensitivity of mechanonociceptors for distension decreased. Painful sensations during the first week of treatment with capsaicin can be attributed to a sensitizing effect of capsaicin on vanilloid receptors.
Hammer
J
J
Abteilung für Gastroenterologie und Hepatologie, Medical University of Vienna, Vienna, Austria. Johann.Hammer@meduniwien.ac.at
D000284:Administration, Oral; D000328:Adult; D021721:Balloon Occlusion; D002211:Capsaicin / Q000008:administration & dosage / Q000494:pharmacology*; D002214:Capsules; D004415:Dyspepsia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D009619:Nociceptors / Q000187:drug effects*; D011312:Pressure; D012684:Sensory Thresholds / Q000187:drug effects; D050916:TRPV Cation Channels / Q000187:drug effects
D002214:Capsules; D050916:TRPV Cation Channels; D002211:Capsaicin