Morphological changes in the salivary glands upon stimulation by receptor-selective agonists. II. Submandibular glands of the mouse

The innervation of the submandibular glands of the mouse by the autonomic nervous system and the influence of receptor-selective mimetics of the neurotransmitter substances on these glands have been studied with histological techniques. The mimetics were administered either via an intraperitoneal injection or via the perfused blood vessels. The acini and granular convoluted tubules were surrounded by both an adrenergic and a cholinergic plexus. Both types of transmitter mimetics were able to stimulate the exocytotic secretion from the acinar cells either via the beta-adrenoceptor or via the cholinergic muscarinic receptor within 45 min of perfusion. Strongest effect was observed after stimulation of the former receptor. Aso 90 min after an intraperitoneal injection it was observed that both isoprenaline and pilocarpine stimulated the granular release from the acinar cells. On the other hand, the granular secretion from the convoluted tubules was predominantly stimulated by adrenergic agonists though these cells, like the acinar cells, received a dual innervation. In contrast to the acinar cells the secretory process in the tubular cells was stimulated via both the alpha- and beta-adrenoceptor. Stimulation of the alpha-adrenoceptor induced the most distinct effect, which found expression in an explosive granular secretion within 15 min of perfusion, during which process the luminal plasma membranes seemed to be disrupted. The effect of isoprenaline was obvious only after 45 min of perfusion. However, 90 min after an intraperitoneal injection of either isoprenaline or phenylephrine the convoluted tubules were almost completely depleted of granules. Stimulation of the cholinergic muscarinic receptor by pilocarpine resulted only in a slight secretory effect, both in vivo and during perfusion.