Ultrastructural study of the submandibular gland of the rat after 6-month exposure to cadmium and zinc in drinking water.

PURPOSE: Cadmium toxicity in the exposure of the general, professional and cigarette smoking populations has been well known. From the dental point of view, it is important to find out whether and how separate and joint exposures to cadmium and zinc affect the structure and function of the submandibular gland, which is the major saliva-releasing gland. Cadmium, a particularly active xenobiotic, damages cellular metabolism at the level of various enzymatic systems of the cell, which may disturb functioning of the salivary glands. Mutual interactions of cadmium and zinc suggest a protective role of zinc through the induction of metallothionein which inactivates cadmium effect. MATERIAL AND METHODS: The aim of the study was to assess the ultrastructural picture of chosen cell organelles of the submandibular salivary gland of the rat exposed to cadmium and zinc. The study used 90 male Wistar rats, of the initial b.w. 150-180 g. The animals were exposed to cadmium and/or zinc for 6 months. Cadmium was received in aqueous solutions of cadmium chloride with drinking water at a concentration of 5 mg Cd/dm3 or 50 mg Cd/dm3. Zinc was also given in aqueous solutions of zinc chloride ad libitum at concentrations of 30 mg Zn/dm3 and 60 mg Zn/dm3. RESULTS: The ultrastructural changes in the mucous and serous cells of the submandibular salivary gland were most pronounced at cadmium concentration of 50 mg Cd/dm3 and were mainly observed in the cell nucleus, Golgi Apparatus and secretory granules of the salivary gland cells. CONCLUSIONS: 1. Exposure to cadmium induces ultrastructural changes in the submandibular gland, which are dose and time of exposure. 2. Exposure to zinc did not affect significantly the ultrastructural picture of cells of the submandibular gland. 3. Zinc administered together with cadmium reduces the intensity of ultrastructural changes in the submandibular gland.