Studies show an association between cadmium (Cd) exposure and prediabetes or type II diabetes mellitus. We have previously reported that Cd causes decreased levels of serum leptin in rats following 12 weeks of daily Cd dosing (0.6 mg/kg/b.w./day). Since leptin plays an important role in metabolism, we examined the effects of Cd on rats and db/db mice, which are deficient in leptin receptor activity. We gave rats and mice daily subcutaneous injections of saline (control) or CdCl2 at a dose of 0.6 mg/kg of Cd for 2 weeks, followed by 2 weeks of no dosing. At the end of the 4-week study, exposure to Cd resulted in a more rapid increase in blood glucose levels following an oral glucose tolerance test in db/db vs. lean mice. During the two weeks of no Cd dosing, individual rat bodyweight gain was greater (p ≤ 0.05) in Cd-treated animals. At this time point, the combined epididymal and retroperitoneal fat pad weight was significantly greater (p ≤ 0.05) in the Cd-treated lean mice compared to saline-treated controls. Although this pilot study had relatively low N values (4 per treatment group for mice and 6 for rats) the results show that clinically relevant levels of Cd exposure resulted in diabetogenic as well as obesogenic effects.
Keywords: cadmium; db/db mouse; diabetes mellitus; leptin; obesity.