Impact of iron status on cadmium uptake in suckling piglets

Low iron status is known to increase the uptake of dietary cadmium in both adolescents and adults and there are indications that cadmium is absorbed from the intestine by the two major iron transporters divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1). In addition, it has been suggested that duodenal metallothionein (MT) may limit the transport of cadmium across the intestinal epithelium. The present investigation was undertaken to examine whether iron status influences cadmium absorption in newborns by applying a model of suckling piglets and the possible roles of duodenal DMT1, FPN1 and MT. An oral cadmium dose (20 microg/kg body weight) was given daily for 6 consecutive days on postnatal days (PNDs) 10-15 to iron-deficient or iron-supplemented piglets. The cadmium dose was chosen to keep the cadmium level at a realistically low but still detectable level, and without inducing any adverse health effects in the piglets. As indicators of cadmium uptake, cadmium levels in blood and kidneys were measured on PND 16 by inductively coupled plasma-mass spectrometry (ICP-MS). Cadmium levels in blood were statistically significantly correlated with cadmium levels in kidneys. The cadmium uptake was not higher in iron-deficient suckling piglets; rather, we detected a higher cadmium uptake in the iron-supplemented ones. The expression and localisation of DMT1, FPN1 and MT were not affected by iron status and could therefore not explain the findings. Our results suggest that there are developmental differences in the handling of both iron and cadmium in newborns as compared to adults.