Taste receptors of the gut: emerging roles in health and disease

Recent progress in unravelling the nutrient-sensing mechanisms in the taste buds of the tongue has triggered studies on the existence and role of chemosensory cells in the gut. Indeed, the gastrointestinal tract is the key interface between food and the human body and can sense basic tastes in much the same way as the tongue, through the use of similar G-protein-coupled taste receptors. These receptors taste' the luminal content and transmit signals that regulate nutrient transporter expression and nutrient uptake, and also the release of gut hormones and neurotransmitters involved in the regulation of energy and glucose homeostasis. Hence, they play a prominent role in the communication between the lumen, epithelium, smooth muscle cells, afferent nerve fibres and the brain to trigger adaptive responses that affect gastrointestinal function, food intake and glucose metabolism. This review summarises how sensing of nutrients by taste receptors along the gut plays a key role in the process of digestion, and how disturbances or adaptations of these chemosensory signalling pathways may contribute to the induction or resolution of a number of pathological conditions related to diabetes, obesity, or diet-induced symptom generation in irritable bowel syndrome. Targeting these receptors may represent a promising novel route for the treatment of a number of these diseases.