Tachykinins as targets of gastroenterological pharmacotherapy

The term "tachykinins" is the name for a large family of small peptides. In the digestive tract, tachykinins (substance P, neurokinin A) are neurotransmitters which regulate motor activity, secretion of ions and fluid, and vascular functions. Their effects are mediated by three different receptors (NK(1), NK(2), NK(3)) which are expressed by the gastrointestinal effector systems in a cell-specific manner. Pathophysiological implications of the tachykinins substance P and neurokinin A in the gut include: changes in the expression of tachykinins and tachykinin receptors; implications of tachykinins in gastrointestinal motor disturbances; implications of tachykinins in diarrhea and gastrointestinal inflammation; and implications of tachykinins in visceral sensitivity and pain. Gut disorders of various etiology, particularly those due to infection or inflammation, are related to changes in the gastrointestinal expression of tachykinins and their receptors. It is hypothesized, therefore, that the contribution of tachykininergic neurons to normal gastrointestinal physiology is out of balance in the diseased gut.