fMRI and Visceral Perception Upon Capsaicin Infusion

Brain and Brainstem Activation Following Duodenal Nociceptive Stimulation With Capsaicin, an Exploratory High-resolution fMRI Study in Healthy Volunteers

Brain imaging has shown abnormal brain activations in response to visceral stimulation in patients with the Irritable Bowel Syndrome (IBS) and Functional Dyspepsia (FD). To investigate the possible role of the Nucleus of the Solitary Tract (NTS), the primary relay station in the brainstem for vagal afferents, its activation in IBS and functional dyspepsia patients will be evaluated. Prior to this, an exploratory study in healthy volunteers will be conducted. This will be the first high magnetic field fMRI study (7T) evaluating the possible role of NTS activation in visceral abdominal pain. Moreover, this will be the first pharmacological fMRI study using duodenal capsaicin infusion as a chemical stimulus, which is more physiological than mechano-stimulation in the upper gastrointestinal tract.

Inclusion Criteria:

• Of female sex
• Based on medical history and previous examination, no gastrointestinal complaints can be defined.
• Age between 18 and 65 years.
• BMI between 18 and 30 kg/m2
• Women in fertile age (<55 years old) must use contraception or be postmenopausal for at least two years.
• All subjects should be right-handed.

Exclusion Criteria:

• Presence of metallic prostheses, pacemakers, metal clips on blood vessels, metal parts in the eye, an intrauterine device, metal braces, tattoos and/or other metal objects;
• History of major head trauma or head/brain surgery;
• History of claustrophobia;
• History of severe or chronic cardiovascular, respiratory, urogenital, gastrointestinal/ hepatic, hematological/immunologic, HEENT (head, ears, eyes, nose, throat), dermatological/connective tissue, musculoskeletal, metabolic/nutritional, endocrine, neurological/psychiatric diseases, allergy, major surgery and/or laboratory assessments which might limit participation in or completion of the study protocol;
• Use of medication, including vitamin and iron supplementation, except oral contraceptives, within 14 days prior to start of the study;
• Major abdominal surgery interfering with gastrointestinal function (uncomplicated appendectomy, cholecystectomy and hysterectomy allowed, and other surgery upon judgment of the principle investigator);
• Pregnancy, lactation, wish to become pregnant;
• High alcohol consumption (>15 alcoholic consumptions per week);
• Using drugs of abuse;
• Self-admitted HIV-positive state;
• Known allergic reaction to capsaicin;
• High intake of spicy (capsaicin containing) food (meaning an estimated intake of > than 1.5mg/day), due to possible desensitization of the capsaicin receptor TRPV1 (see further below);
• Administration of investigational drugs or participation in any scientific intervention study which may interfere with this study (to be decided by the principle investigator), in the 180 days prior to the study;
• Any evidence of structural brain abnormalities examined by anatomical MRI will lead to exclusion.