Neuropeptides and Asthma

This chapter discusses effects of airway neuropeptides that are relevant to the pathophysiology of asthma and whether this might lead to new therapeutic approaches in the future. It considers neuropeptide separately, but it is important to recognize that neuropeptides act as cotransmitters of classical autonomic nerves and that each peptide may have interactions with other nerves, resulting in complex effects on a tissue. Vasoactive intestinal peptide is a potent relaxant of human airways in vitro but is ineffective by inhalation, presumably because of metabolism by airway enzymes. Neuropeptides are cotransmitters in classic autonomic nerves and may be regarded as modulators of autonomic effects, perhaps acting to "fine-tune" airway functions and to modulate the release of other neurotransmitters. Although there has been optimism that inhibitors or mimics of neuropeptides might have therapeutic application in asthma, it is unlikely that such drugs would have a major advantage over existing agents.