Enhanced parasympathetic nerve activities in experimentally-induced nasal hypersensitivity

In order to verify the role of cholinergic nerves in nasal allergy and nonspecific nasal hypersensitivity we have evaluated the muscarinic acetylcholine receptors and the activity of choline acetyltransferase in nasal mucosa of TDI-sensitized guinea-pigs at specific points in time during a pre-determined sensitization period. The density of muscarinic receptors was significantly elevated in animals sensitized for 8 and/or 12 weeks as well as in the group which received 12 weeks of sensitization followed by a 4 week rest period. Choline acetyltransferase activity was also enhanced at 4-, 8- and 12 weeks. These observations provide biochemical evidence of the hyperactivity of cholinergic nerves in nasal allergy which has been suggested by clinical and pharmacological studies, and lead to the speculation that enhanced parasympathetic nerve function is implicated in causing and maintaining hypersensitivity and hypersecretion in nasal allergy.