Rectal biopsies from IBS patients or healthy subjects will be taken.

Biopsies will be used for:

1. the isolation of submucosal plexus to perform: 1.1 live nerve recordings and Calcium imaging; 1.2 immunohistochemistry; 1.3 mRNA (Messenger ribonucleic acids) isolation and real time PCR (Polymerase chain reaction);
2. culturing biopsies

On the basis of these observations, the general aim of the study is to move a significant step forward in the current knowledge on human ENS (enteric nervous system) in IBS by establishing a live imaging method to record enteric nerves activity in small intestinal biopsies from humans. This development is unique in its kind as not other research groups have reported successful live recordings with calcium imaging in this preparation.

In particular, the investigators aim:

1. to develop and validate the technique to measure activity in human enteric nerves in the submucous plexus isolated from rectal biopsies from healthy subjects and IBS patients;
2. to characterize this nerve activity in healthy subjects and IBS patients using both calcium imaging to evaluate the effect of different neuromodulators, immunohistochemistry and rtPCR to determine receptor expression levels and identify neurons and glial cells in the submucous ganglia;
3. to investigate whether the biopsies of IBS patients secrete more modulators/cytokines compared to healthy subjects and their potential to activate neurons.
4. to evaluate the influence of different food constituents (cow"s milk, wheat, yeast, gluten and soy) on the local reaction of the rectal mucosa and evaluate mast cell activation/degranulation in biopsies of IBS patients compared to healthy subjects.
5. To evaluate the amount of inflammatory mediators/metabolites in urine samples of IBS patients and healthy volunteers by the use of metabolic profiling

Inclusion Criteria:

• IBS patients (based on ROME III Criteria)
• Healthy subjects

Exclusion Criteria:

- All subjects with not IBS related complaints