Critical Reviews in Oral Biology & Medicine, Vol 4, 591-597, Copyright © 1993 by International & American Associations for Dental Research
Effects of food mastication on rat parotid gland adrenergic and cholinergic cell surface receptors
D. A. Johnson and H. L. Cardenas
Department of Community Dentistry, University of Texas Health Science Center, San Antonio 78284-7917.
Adult male rats were fed diets of differing texture (liquid, powder,
standard pelleted, or bulk pelleted) to alter food mastication. After 2
weeks, the parotid glands were removed and adrenergic and
muscarinic-cholinergic cell surface receptor density (fM bound/mg protein)
and ligand binding dissociation constants (Kd in nM) were determined by
radioligand binding techniques on a crude membrane fraction. For all diets,
gland weight increased as the requirement for food mastication increased
(i.e., liquid < powder < standard pelleted < bulk pelleted). Among
the diets, neither beta-two nor alpha-two receptor density was altered.
Beta-one receptor density was directly related to dietary mastication.
Compared with the standard pelleted diet, beta-one receptor density was
reduced 21% for the liquid diet and 7% for the powdered diet; for the
bulk-pelleted diet, beta-one receptor density was increased 11%. With
respect to alpha-one receptor density, it was not affected by the liquid or
powdered diet when compared with the standard pelleted diet, but alpha-one
receptors were increased 14% with the bulk-pelleted diet.
Muscarinic-cholinergic receptor density for the liquid diet fed rats was
27% less than for the standard-pelleted diet; powdered diet did not differ
from standard pelleted, while that for the bulk-pelleted diet was increased
6%. With but minor exceptions, ligand binding affinity was unaffected by
the changes in diet texture. These studies demonstrate that dietary
mastication as well as affecting parotid gland weight, cell size, and
saliva production also influences autonomic cell surface receptor density.
