The effects of a long-term powdered diet on the amounts of two principal neurotransmitters in the major salivary glands and on stimulated salivary secretion in mice.

The amounts of 2 principal neurotransmitters, acetylcholine (ACh) and norepinephrine (NE) in the 3 major salivary glands, and pilocarpine-, isoproterenol- and phenylephrine-induced salivation in male mice fed a powdered diet for 16 weeks were compared with those in mice fed a standard pellet diet (as control). There were no significant differences in the final body weights of mice fed the powdered diet and the control diet. The only salivary gland in the powdered diet fed mice to increase significantly in weight was the sublingual gland. Mice fed the powdered diet had significantly increased ACh concentrations and contents, but had decreased amounts of NE, in the submandibular and sublingual, but not the parotid glands. The salivation stimulated by pilocarpine was markedly decreased in mice fed the powdered diet, whereas the salivation stimulated by phenylephrine or isoproterenol was not. These findings indicate that reduced mastication affects not only the secretory function but also the amounts of these neurotransmitters in the salivary glands of mice.