Peripheral actions of tachykinins

Tachykinins mediate a variety of physiological processes in the gastrointes tinal, pulmonary and genitourinary tract mainly through the stimulation of NK1 and NK2 receptors. Preclinical evidence obtained through the use of sel ective tachykinin receptor antagonists indicates that endogenous tachykinin s are involved in augmented smooth muscle contraction, vasodilatation, chem otaxis and activation of immune cells, mucus secretion, water absorption/se cretion. Recent evidence also suggests that endogenous tachykinins released at the peripheral level may play a role in visceral inflammation, hyperref lexia and hyperalgesia. Possible mechanisms underlying the stimulation of p rimary afferent neurons by tachykinins may involve a direct excitation of t hese neurons and the release of mediators which sensitise or stimulate sens ory nerves. Tachykinin receptor antagonists could have a clinical utility i n several human diseases such as irritable bowel syndrome, asthma, and in m icturition disturbances characterized by a hyperactive bladder (C) 2000 Har court Publishers Ltd.