WEIGHT-LOSS ALTERS ORGAN CONCENTRATIONS AND CONTENTS OF LEAD AND SOMEESSENTIAL DIVALENT METALS IN RATS PREVIOUSLY EXPOSED TO LEAD

The loss of adipose tissue during energy restriction may be accompanie d by a loss of lean body mass, including bone mass. Because most of th e body lead burden is in the skeleton, we studied the effects of weigh t loss on the concentrations of lead in bone, blood and several organs in rats with prior but not current lead exposure. Concentrations of t he essential divalent metals calcium, copper, iron, magnesium and zinc were also determined for comparison with lead. Lead-exposed rats (n = 25) were randomly assigned to one of three treatment groups: weight m aintenance (WM), moderate weight loss (MWL) or substantial weight loss (SWL). For the two last-named groups, food intake was restricted for 4 wk to 70 and 40% of that of the WM, group. Lead concentrations did n ot differ significantly (ANOVA, P > 0.05) among the three groups for b lood, brain and bone. Significantly higher liver lead concentrations w ere observed in the SWL rats than in the WM and MWL groups. In general , organ concentrations of calcium; copper, magnesium and zinc were eit her lower or did not differ in the groups losing weight compared with the WM group. In contrast, organ iron concentrations of the SWL group were higher than those of the other groups except in brain where there were no significant differences. The total liver content of lead was highest in the SWL group, but the lead content of other organs did not differ among the treatment groups. The contents of calcium, copper, m agnesium and zinc generally were lower in the MWL and SWL groups than in the WM group in the liver and some of the other organs. The results demonstrate that weight loss can increase the quantity and concentrat ion of lead in the liver, even in the absence of continued lead exposu re. The data also demonstrate considerable differences among organ div alent metals in response to weight loss.