Control of nerve growth and plasticity

Respiratory function is under close control of the autonomic nervous system. Recent data indicate that dysfunction and dysregulation of both the non-adrenergic non-cholinergic (NANC) and cholinergic system contribute to the pathogenesis of chronic inflammatory lung disease such as bronchial asthma. Sensory neurons of the NANC system in particular exhibit a great degree of plasticity. It has been shown that neurotrophins play an important role in modulating sensory innervation in such conditions. In addition, several inflammatory mediators also contribute to sensory nerve plasticity in this context. Cholinergic nerves represent the dominant broncho-constrictory pathway and the role of the muscarinic M(2) receptor has been recently characterized in this regard. In summary, recent data provide new insights into dysfunction and dysregulation of the autonomic nervous system as observed in chronic inflammatory lung disease.