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

The innervation of the parotid 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 receptor-selective agonists were administered either via an intraperitoneal injection or via perfusion of the glands, followed by a rapid perfusion-fixation. The acinar cells were surrounded by both an adrenergic and a cholinergic plexus. Both types of transmitter mimetics were able to induce exocytosis from the parotid acinar cells. Administration of either isoprenaline or pilocarpine via the perfusion fluid resulted within 15 min in a distinct effect on the acinar cells, though in the doses used, the beta-adrenergic effect dominated the cholinergic influence. Also 90 min after an intraperitoneal injection it was observed that both agonists stimulated the granular release. Stimulation of the alpha-adrenoceptor resulted only in a transient formation of vacuoles in the acinar cells. These results confirm the biochemical data reported previously, which indicated that both isoprenaline and pilocarpine induce a significant amylase secretion, in contrast to phenylephrine. In addition these results show that the perfusion technique is excellently suitable for studying morphological effects of secretagogues on the salivary glands.