Neuropeptides and nasal secretion.

Recent research has disclosed that neurotransmitters and neuropeptides released within the autonomic nervous system exert homeostatic control of nasal secretion. Although cholinergic and adrenergic influences have long been thought to be the predominant mechanisms, the nonadrenergic, noncholinergic responses may have more suitable, longer-lasting effects. Peptides from sensory nerves, such as calcitonin gene related peptide, substance P, and neurokinin A, may participate in axon response-mediated vasodilation and plasma extravasation. Substance P and gastrin releasing peptide may induce glandular secretion. Defensive responses to local mucosal injury may be amplified by axon response, which initiates these vascular and glandular reactions. Cholinergic effects are primarily responsible for mediating parasympathetic reflexes, but vasoactive intestinal peptide may regulate acetylcholine release, augment glandular secretory responses, and have a vasodilatory effect. In the sympathetic nervous system, neuropeptide Y probably functions as a long-acting vasoconstrictor. Integration of sympathetic and parasympathetic influence may regulate the normal nasal cycle, and sensory and parasympathetic defensive reflexes may respond to epithelial and mast cell stimulation. It is possible, then, that the pathophysiology of vasomotor rhinitis involves an exaggeration of these neural influences.