Intrarectal injection of glycerol induces hypersensitivity to rectal distension in healthy subjects without modifying rectal compliance.
BACKGROUND
Rectal sensory thresholds are lowered in patients with irritable bowel syndrome (IBS), reflecting visceral hyperlagesia, which might be related to subclinical inflammation.


OBJECTIVE
To evaluate the effects of an intraluminal injection of glycerol, a mucosal irritant, on rectal tone and perception of distension in 12 healthy subjects.


METHODS
Rectal tone was evaluated with a barostat. First sensation, need to defecate and pain thresholds were evaluated during isobaric phasic distensions, before and 20 and 120 min after injection of 10 ml glycerol in the rectum.


RESULTS
Baseline bag volume (97.9 +/- 56.2 ml) significantly decreased 20 min (49.7 +/- 42.2 ml; P= 0.026) and 120 min (66.5 +/- 38.3 ml; P= 0.050) after injection of glycerol, indicating its hypertonic effect. The pressure defining sensory thresholds was decreased significantly 20 min after glycerol injection: first sensation, 14.6 +/- 2.9 versus 18.3 +/- 7.2 mm Hg (P = 0.01); need to defecate, 19.6 +/- 3.7 versus 26.0 +/- 6.9 mm Hg; pain, 23.8 +/- 4.5 versus 35.6 +/- 9.5 mm Hg (P = 0.001). This effect was maintained for 120 min after injection of glycerol. Slopes of the compliance curves did not differ before and after injection of glycerol.


CONCLUSIONS
Intraluminal injection of glycerol significantly increases rectal tone and sensitizes healthy volunteers to rectal distension, since they show significantly lower thresholds after glycerol. This could constitute a model of visceral hypersensitivity in healthy volunteers.
Bouin
M
M
Gastroenterology Unit, CHU Rangueil, Toulouse, France.
Delvaux
M
M
Blanc
C
C
Lagier
E
E
Delisle
M B
MB
Fioramonti
J
J
Buéno
L
L
Frexinos
J
J
D000285:Administration, Rectal; D000328:Adult; D001706:Biopsy; D003672:Defecation; D005990:Glycerol / Q000008:administration & dosage* / Q000494:pharmacology*; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D017288:Pain Threshold; D012007:Rectum / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000502:physiology; D012016:Reference Values
D009569:Nitric Oxide; D005990:Glycerol