Gustatory-salivary reflexes induce non-adrenergic, non-cholinergic acinar degranulation in the rat parotid gland

Abstract

In the presence of the muscarinic blocker atropine, the α-adrenoceptor blocker phentolamine and the β-adrenoceptor blocker propranolol (2 mg kg-1 of each, I.P.), the numerical density of parotid acinar secretory granules was reduced by 32% in response to ascorbic acid (0.5 M) applied on the tongue every 30 s over 30 min in awake rats. This non-adrenergic, non-cholinergic (NANC) response was entirely dependent on an intact auriculo-temporal nerve supply. The NANC mechanisms were found to be potentially responsible for almost all of the exocytotic response that occurs in the absence of the three autonomic receptor blockers. No sympathetic contribution to the exocytotic response was found and furthermore, studies in parasympathetically denervated glands showed that the sympathetic contribution to the salivary flow was small.