The effect of zinc supply on cadmium-induced changes in the tibia of rats

It has been determined that zinc supplementation (240 mug Zn/ml) during (fo r 12 weeks) or after (for 2 weeks) cadmium exposure (50 mug Cd/ml for 12 we eks) can prevent the accumulation and toxic action of Cd in the tibia of ra ts. The exposure to Cd led to disturbances in bone metabolism reflected by changes in the chemical composition of bone and decreased bone mineral dens ity (osteomalacian changes). The Zn supply in conditions of Cd intoxication completely prevented the Cd-induced increase in percentage of water conten t and decrease in tibia ash weight, ash weight/dry weight, non-org. comp./o rg. comp., Zn content and concentration. Moreover, Zn partly protected from the decrease in Ca concentration and content, percentage of non-organic co mponents content, Ca/wet weight, Ca/ash weight and Ca/dry weight. Zn admini stered after Cd exposure partly but not completely, protected from Cd-induc ed decrease in percentage of non-organic components content, Ca/wet weight as well as Ca content and concentration. This protective effect on bone was most evident when Zn was administered during Cd exposure. But Zn, independ ently of the manner of its administration, did not prevent Cd accumulation in the tibia. Our results suggest that Zn supply in conditions of simultane ous exposure can prevent Cd-induced bone loss to some extent, and used afte r Cd treatment can give therapeutic benefits. (C) 2001 Elsevier Science Ltd . All rights reserved.