Figure 2.

Interactions between serotonergic and purinergic signaling in gut physiology. Mechanical stress activates a mechanosensor on EC to release 5-HT that has a myriad of physiological functions, including activation of enteric neural secretory and motility reflexes, transmission of satiety signals, transmission of pain signals, and induction of emesis. Mechanical stress also releases purinergic mediators (ATP and UTP) from EC and epithelial cells to tightly modulate the secretion of 5-HT as well as gut reflexes. Abnormal 5-HT signaling occurs in GI disorders and IBD, but little is known about how this occurs in EC cells. 5-HT is also implicated in the pathogenesis of inflammation. Purinergic signaling is very sensitive to inflammation, and this is also the case in EC cells. Our working hypothesis is that purinergic mechanisms are linked to abnormal 5-HT secretion and hence signaling in inflamed gut.