Intracolonic injection of glycerol: a model for abdominal pain in irritable bowel syndrome?
OBJECTIVE
Abdominal pain is the main symptom in patients with irritable bowel syndrome (IBS). Glycerol is an irritant of colonic mucosa. The aim of this study was to evaluate the effects of an intraluminal injection of glycerol on colonic motility and tone in patients with IBS and their modulation by drugs.


METHODS
Colonic motility was evaluated using electromyography, and colonic tone was assessed using a barostat. Glycerol was injected in the right colon or the rectum.


RESULTS
After intracolonic injection of glycerol, a strong abdominal colic occurred and was associated with an increase in long spike burst activity (+280%), which was eliminated by previous administration of lidocaine and was not observed after paraffin oil. When glycerol was injected intrarectally, abdominal pain occurred and long spike burst activity was increased (+240%) in the left colon. Simultaneously, colonic tone decreased (-70%) and high-amplitude phasic contractions occurred (10 +/- 1/patient). This rectocolonic reflex was reproducible in the same patient. Drugs acting on visceral afferent pathways (octreotide and granisetron) did not modify this reflex, whereas the spasmolytic drug phloroglucinol inhibited phasic contractions without affecting tone.


CONCLUSIONS
Intraluminal injection of glycerol triggers viscerovisceral reflexes, resulting in abdominal pain in patients with IBS. It could be used as a model for the study of effects of drugs on pain in these patients.
Louvel
D
D
Laboratory of Digestive Motility, Gastroenterology Unit, CHU Rangueil, Toulouse, France.
Delvaux
M
M
Staumont
G
G
Camman
F
F
Fioramonti
J
J
Bueno
L
L
Frexinos
J
J
D015746:Abdominal Pain / Q000139:chemically induced / Q000209:etiology* / Q000503:physiopathology; D000328:Adult; D000368:Aged; D003106:Colon / Q000187:drug effects / Q000503:physiopathology; D003109:Colonic Diseases, Functional / Q000150:complications*; D004576:Electromyography; D005260:Female; D005765:Gastrointestinal Agents / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects; D005990:Glycerol / Q000008:administration & dosage* / Q000494:pharmacology; D017829:Granisetron / Q000494:pharmacology; D006801:Humans; D007267:Injections / Q000379:methods; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D015282:Octreotide / Q000494:pharmacology; D010276:Parasympatholytics / Q000494:pharmacology; D010696:Phloroglucinol / Q000494:pharmacology; D012018:Reflex / Q000187:drug effects; D015203:Reproducibility of Results; D012702:Serotonin Antagonists / Q000494:pharmacology
D005765:Gastrointestinal Agents; D005990:Glycerol; D017829:Granisetron; D015282:Octreotide; D010276:Parasympatholytics; D010696:Phloroglucinol; D012702:Serotonin Antagonists