The Effect of Serotonergic Modulation on Intestinal Permeability and Visceral Hypersensitivity in Healthy Individuals and Irritable Bowel Syndrome (IBS) Patients

Inclusion criteria

• IBS-patients

Inclusion criteria

• IBS will be diagnosed according to the Rome III criteria* [35]:

Recurrent abdominal pain or discomfort at least 3 days per month in the last 3 months associated with 2 or more of the following:

• Improvement with defecation
• Onset associated with a change in frequency of stool
• Onset associated with a change in form (appearance) of stool

• Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis
• Discomfort means an uncomfortable sensation not described as pain. In pathophysiological research and clinical trails, a pain/discomfort frequency of at least 2 days a week during screening evaluation is an indication for subject's eligibility.
• Based on the medical history and previous examination, no other causes for the abdominal complaints can be defined.
• Age between 18 and 65 years

Healthy individuals

Inclusion criteria

All subjects will be screened with a standardized psychiatric examination using the mini international neuropsychiatric interview (MINI) to determine present psychiatric state. General psychological state will be assessed using the 17 item Hamilton depression rating scale (HAM-D17), the Dutch version of the symptom checklist (SCL-90) and the hospital anxiety and depression rating scale (HADS). The psychiatric evaluation will be carried out by a psychiatrist. Volunteers with deviating scores on any topic will be excluded from participation.

Healthy individuals between age 18 and 65 years will be included in the study.

Exclusion criteria

• Exclusion criteria for IBS patients:

• Severe co-morbidity hindering a rectal barostat procedure, according to the gastroenterologist's perception.
• Abdominal surgery, except for uncomplicated appendectomy, laparoscopic cholecystectomy or hysterectomy.
• Inability to stop medication that can influence gastrointestinal motility or perception (like loperamide, butylscopolamine, psylliumsead (metamucil), duspatal, metoclopramide, domperidon, erytromycine), or serotonin metabolism (carbidopa) for at least 3 days before tests.
• History of psychiatric disorders including use of psychoactive medication or psychological symptomatology, defined as a diagnosis on the MINI, HAM-D17 score above 18, global severity index score on SCL-90 for females ≥150, for males ≥131, or HADS scores ≥ 8. First-degree family members with psychiatric disorders
• Administration of investigational drugs in the 180 days prior to the study
• Premenstrual syndrome, dieting, pregnancy, lactation
• Excessive alcohol consumption (>20 alcoholic consumption per week)
• Smoking
• Blood donation within 3 months before the study period
• Self-admitted HIV-positive state
• Irregular day-night rhythm

Exclusion criteria

for healthy individuals:

• History of gastrointestinal, psychiatric disorders including use of psychoactive medication or psychological symptomatology, defined as a diagnosis on the MINI, HAM-D17 score above 18, global severity index score on SCL-90 for females ≥150, for males ≥131, or HADS scores ≥ 8 First-degree family members with psychiatric disorders
• Use of medication, except oral contraceptives, within 14 days prior to testing
• Administration of investigational drugs in the 180 days prior to the study
• Previous abdominal surgery (other than uncomplicated appendectomy, laparoscopic cholecystectomy and hysterectomy)
• Premenstrual syndrome, dieting, pregnancy, lactation
• Excessive alcohol consumption (>20 alcoholic consumption per week)
• Smoking
• Blood donation within 3 months before the study period
• Self-admitted HIV-positive state
• Irregular day-night rhythm
• Severe co-morbidity hindering a rectal barostat procedure, according to the gastroenterologist's perception.