The effect of poisoning doses of selenium on serum matrix-degrading enzymes activity was investigated in rats intoxicated with selenium. Fifteen animals were receiving orally sodium selenite in a daily dose of 300 g/kg body weight. Intoxication with selenium was carried out for 10 weeks. The present study revealed significant increase in activities of enzymes involved in the connective tissue matrix metabolism i.e. -glucuronidase, N-acetyl- -glucosaminidase, elastase and collagen peptidase. There was no change in the cathepsin activity. The relative enzyme activities calculated over protein level resulted in higher values than those found in direct measurements. Serum e nzyme activity was increased most for elastase (about 31 %) and N-acetyl- -glucosaminidase (about 33 %) based on activity per gram of protein. The current data indicate that lysosomes are target organelles for selenium toxicity. Generalized increase in lysosomal enzymes activity c ontributes to the altered metabolism of the connective tissue in selenium-intoxicated animals. The mechanisms that lead to the increase of lysosomal enzymes activity in rats receiving poisoning doses of selenium could be related to biochemical disturbances caused by selenium toxicity.

        Key words: selenium toxicity, lysosomes, matrix-degrading enzymes, rats