5-HT in the enteric nervous system: gut function and neuropharmacology

In recent times, the perception of functional gastrointestinal disorders such as irritable bowel syndrome (IBS) has shifted fundamentally. Such disorders are now thought of as serious diseases characterized by perturbations in the neuronal regulation of gastrointestinal function. The concept of visceral hypersensitivity, the characterization of neuronal networks in the ‘brain–gut axis’ and the identification of several novel 5-HT-mediated mechanisms have contributed to this shift. Here, we review how some of the more promising of these new mechanisms (e.g. those involving 5-HT transporters and the 5-HT2B, 5-HT7 and putative 5-HT1p receptors) might lead to a range of second-generation therapies that could revolutionize the treatment of functional gastrointestinal disorders, particularly IBS.