Cadmium-mediated induction of cellular defence mechanism: a novel example for the development of adaptive response against a toxicant.

Early response to the exposure of cadmium includes the enhancement in lipid peroxidation with the concomitant impairment in antioxidative defence mechanism. This investigation deals with the delayed response of cadmium induced stimulation of endogenous defence response against its oxidative damage. The administration of cadmium led to an increase in the hepatic enzymatic and nonenzymatic defence armory in a dose dependent manner 72 hrs post its administration. This includes respectively an increase in the activities of superoxide dismutase, glutathione peroxidase, glucose-6-phosphate dehydrogenase and in the levels of glutathione, metallothionein and zinc. Cadmium administration also stimulated serum ceruloplasmin activity in a dose dependent manner. These changes are accompanied by the concomitant decrease in the peroxidative damage to lipids. Our results suggest the development of a delayed adaptive/defence response as a result of exposure to cadmium.