Neurotransmitters and neuroreceptors in the lower urinary tract

In addition to transmitters stored in and released from terminals of efferent nerves, transmitters of afferent nerves and their receptors are also involved in the control of lower urinary tract function. Tachykinins, such as substance P and neurokinins A and B, and other neuropeptides have been demonstrated in nerves of the the lower urinary tract and shown to be able to influence bladder function. Drugs affecting these nerves by causing release of tachykinins, and agents antagonizing tachykinin receptors, may be of therapeutic interest. New information on the alpha-adrenoceptor and muscarinic receptor subtypes mediating contraction of the human urethra and detrusor, respectively, has emerged, and may be the basis for the development of compounds with selectivity for the urethra or the bladder 'Non-classical' transmitters, such as nitric oxide, may also be of importance for bladder function. Nitric oxide derived from nerves seems to be involved in reflex relaxation of the outflow region at the start of micturition. However, nitric oxide derived from other sources may have a role in bladder disorders, such as interstitial cystitis.