Sympathetic nerve stimulation induces vasoconstriction and consequent decreases nasal airway resistance. Parasympathetic nerve stimulation on the other hand, promotes secretion from nasal airway glands and nasal congestion. The nasal mucosa also contains nerves of the non-adrenergic, non-cholinergic (NANC)- system. Neuropeptides from the latter nerves (substance P, neurokinin A and K, and calcitonin gene-related peptide) are suspected to play a role in vasodilatation, mucus secretion, plasma extravasation, neurogenic inflammation, and mast cell nerve interactions. However, the magnitude of their role is uncertain . Further investigations concerning the role of the nervous system in ARS are required
