A histological study of the effects of different alpha-adrenergic and cholinergic agonists on the rat submandibular gland.

Rat submandibular glands were exposed to various sialagogues, including carbachol, clonidine, noradrenaline and cyclocytidine. The effects of these drugs were morphologically compared. Clonidine, which is an alpha-2-agonist, caused no depletion of granules in the serous cells examined. Noradrenaline and cyclocytidine, which are alpha-1-agonists, showed remarkable depletion of secretory granules in the serous cells. Carbachol caused visible and abundant salivation in the animals, but was found to produce only partial granular depletion of both serous and mucous cells. To induce experimentally a complete depletion of granular serous cells, cyclocytidine was found to be an excellent choice as a sialagogue with no side-effects on the cardiac and respiratory system.