Effects of chronic dietary cadmium on hepatic glutathione levels and glutathione peroxidase activity in starlings (Sturnus vulgaris)

The effects of chronic exposure to dietary cadmium on the levels of hepatic glutathione (GSH) and on the activity of the glutathione peroxidase enzymes (GSH-Px) were studied for the first time in starlings (Sturnus vulgaris). Thirty-three individuals (17 females and 16 males) were divided into three groups: One represented the untreated control and two were respectively fed with diets containing 10 and 50 ppm cadmium chloride (CdCl2). The total duration of treatment was 22 weeks. The three groups respectively accumulated mean hepatic Cd residues of 2.29, 75.71, and 208.49 ppm. Hepatic GSH increased in the treated groups respectively 24% and 52% in comparison to controls. Total GSH-Px activity in the liver was inhibited in the group fed with 50 ppm, due to inhibition of the selenium-dependent fraction of the enzyme, while the selenium-independent fraction did not change significantly. During the treatment, after 14 weeks of exposure to cadmium, the 50 ppm-treated group showed a 47% decrease of the activity of the selenium-dependent GSH-Px and a 50% increase of the somatic liver index in comparison with controls.