[The nonadrenergic, noncholinergic neuropeptide system and asthma].

An understanding of the non adrenergic non cholinergic nervous system and its implication in the pathogenesis of asthma would benefit by the identification and localisation of the numerous natural bioactive peptides at the pulmonary level. In the past few years two components of the non adrenergic non cholinergic nervous system have been characterised. A bronchodilator component which would be mediated by "vaso-active intestinal peptide" (VIP) and the "peptide histidine methionine" (PHM). A broncho-constrictor component which would be mediated by the neurokinins (substance P (SP), neurokinin A (NKA) and the "calcitonin gene related peptide" (CGRP)). These neuropeptides, in vitro as well as in vivo, have effects which are not limited to the regulation of bronchial smooth muscle tone. In effect, they may intervene in the regulation of vascular tone, in the production of mucous and in the expression of immediate hypersensitivity reactions at pulmonary level. Several neuropeptides are present or co-exist with classical neurotransmitter in the afferent nerve endings of the pulmonary efferents. This co-existence of several neurotransmitters in the same nervous fibres raised the questions as to their interactions at the pre or post synaptic level. The implication of these neuropeptides in the pathogenesis of asthma rests on numerous experimental arguments. This recent aspect in the pathophysiology of asthma allows us to hope for new therapeutic approaches.