Light-microscopic and fluorescent histochemical investigations on the salivary glands of rats after isoproterenol treatment.

The effect of isoproterenol (IPR) on the salivary glands of the rat were investigated after single and repeated administration of 80 mg/kg body weight subcutaneously. Adrenergic nerve fibres were demonstrated with the aid of formalin-induced fluorescence, and cholinergic fibres by means of the acetylcholinesterase reaction. After a single dose of IPR the acini of the submandibular and parotid glands were depleted and then hypertrophic and hyperplastic. Large scattered cells with retained secretory granules transiently occurred after three days' treatment. They were identified as cells which degenerated mainly during mitosis. The distribution pattern of the autonomic nerve fibres in both glands adjusted to the changes preformed by the acini in the course of treatment. After long-term treatment there was a distinct loss of fibre structures and intensity of fluorescence. Thus it can be concluded that the autonomic fibres degenerate. The effect of IPR on the proliferation kinetics of the salivary glands is discussed. The fluorescent histochemical results are compared with the electron-microscopic findings in autonomic nerves reported in the literature.