State of iron repletion and cadmium tissue accumulation as a function of growth in young rats after oral cadmium exposure

Abstract

To check the hypothesis that adequate dietary iron supplementation reduces cadmium retention and cadmium-induced anaemia during fast growth, three different dietary iron concentrations (6 mg/kg = iron-deficient; 55 mg/kg = marginal iron supply; 180 mg/kg = luxurious iron supply) were offered to growing rats. Four groups of rats at different age (44 days approximately = 150 +/- 6 g, 49 days approximately = 180 +/- 3 g, 57 days approximately = 220 +/- 4 g, and 84 days approximately = 295 9 g) received a diet with 55 mg Fe/kg which is a marginal iron-supply during growth. Six animals in each age group were exposed to 10 mg Cd/l as CdCl2 in the drinking water for 1 week; six animals in each age group received no cadmium. In the youngest and oldest groups additional 6 animals were exposed to the same cadmium dose but received an iron-deficient (6 mg Fe/kg) and an iron-adequate diet (180 mg Fe/kg) together with corresponding controls. The state of iron repletion was monitored by the tissue iron content in liver, kidney, and duodenum as well as by the concentrations of haemoglobin, plasma iron and plasma transferrin. The youngest animals showed the highest percent weight increases. Cadmium administration influenced neither growth rates nor food and water intake. At a dietary iron content of 55 mg/kg, iron repletion was negatively correlated to growth while the cadmium content in liver and kidney showed a positive correlation. At fast growth, a dietary iron content of 6 mg/kg lead to iron-deficiency anaemia and high cadmium retention. At all dietary iron concentrations, cadmium retention as well as the cadmium-related reduction in haemoglobin concentration was significantly higher at fast growth. Adequate dietary iron supplementation reduced cadmium retention and cadmium-induced anaemia significantly. Thus, the delicate balance between iron supply and the increased iron demand during growth can be disturbed within one week by a daily cadmium intake as low as 0.7-1.3 mg Cd/kg body weight.

Cadmium distribution and toxicity in tissues of small rodents

“…Cadmium (10 mg Cd/l as CdCl 2 in distilled water) decreased the hepatic level of iron in rats even with a high dietary content of iron (180 mg/kg) (Schü mann et al, 1996). The same tendency was observed in the kidney.…”

“…Cadmium levels in the body build up with age and the rate of accumulation is significantly higher during high growth phases than with the lower growth phases of mature animals (Schü mann et al, 1996). The half-life of cadmium in mice and rats is about 200 -700 days, but the time of its tissue absorption and retention depends on the chemical form of the administered element.…”

Participation of metal transporters in cadmium transport from mother rat to fetus

“…It is well known that DMT1 protein levels are upregulated in anemic rats (Thompson et al, 2007;Fleming et al, 1998). It has been reported that oral Cd intake reduces hemoglobin concentration of rat and leads to iron-deficiency anemia (Whanger, 1979;Schumann et al, 1996). In this study, hematocrit and hemoglobin were measured to investigate whether Cd administration caused anemia or not.…”

Smoking, cereal consumption, and supplementation affect cadmium content in breast milk

“…Such an Fe-Cd interaction has been described by Satarug et al (2004): non-smoking women with low Fe stores had a three-fold greater Cd burden compared to non-deficient women. Experimental data revealed that adequate dietary Fe supplementation reduced Cd retention and Cd-induced anemia (Schumann et al, 1996). Honda et al (2003) reported that increased Cd concentrations might affect Ca secretion in breast milk.…”