[Irritable bowel syndrome: from the gut to the brain-gut]

Irritable bowel syndrome is not only a digestive motor disorder. It is a multifactorial disease for which many data have highlighted the pathophysiological importance of visceral hypersensitivity in the onset of symptoms, particularly abdominal pain. Hypersensitivity is due either to an afferent neurons disfunction at the enteric nervous system level, either to an abnormal brain-gut axis processing of sensory or nociceptive inputs arising from the gut, at the spinal or supraspinal level. Disturbances of the autonomic nervous system occur in IBS as a consequence of this brain-gut axis dysfunction. Neurological abnormalities may be triggered by inflammation, mast cell dysfunction or increased intestinal permeability while the neuro-immune consequences of stress (mainly chronic) play a major role in the genesis and the maintenance of irritable bowel syndrome. The role of emotions and mood disturbances cannot be omitted in the interpretation the central processing of digestive sensory inputs. Neurosciences, in particular brain imaging techniques, have contributed to this better understanding of irritable bowel syndrome pathophysiology. It is likely to play a major role in the future to improve our knowledge of the brain-gut axis function (mechanisms, neurotransmitters and receptors involved both in normal and pathological conditions). This knowledge is crucial because of the need for updated treatment strategies and new pharmacological and/or cognitive or behavioral therapies.