Cadmium-induced injury and the ameliorative effects of selenium on chicken splenic lymphocytes: mechanisms of oxidative stress and apoptosis.
Cadmium (Cd) is an important environmental pollutant present in soil, water, air, and food. Selenium (Se) can antagonize some metal element toxicity including Cd. To investigate the cytotoxicity of Cd and the protective effects of Se on bird immunocytes in vitro, chicken splenic lymphocytes with CdCl2 (10(-6) mol/L), Na2SeO3 (10(-7) mol/L), and the mixture (10(-7) mol/L Na2SeO3 and 10(-6) mol/L CdCI2) were incubated for 12, 24, 36, and 48 h, respectively. A high level of malondialdehyde (MDA) and reactive oxygen species (ROS) productions were observed in Cd treatment group; the activities of catalase (CAT), glutathione peroxidise (GSH-Px), superoxide dismutase (SOD), and the mitochondrial inner transmembrane potential (ΔΨm) were significantly lower in Cd treatment group than those in controls (P < 0.05 or P < 0.01). In contrast, Se significantly improved the activities of antioxidant enzymes and reduced MDA and ROS levels compared to Cd treatment alone group, although not restored to the levels of control group. The population of apoptosis cells demonstrated that Cd induces the apoptosis of chicken splenic lymphocytes; in addition, increased mRNA level of Bak, p53, caspase-3, caspase-9, and cytochrome c (Cyt c) and decreased Bcl-2, Bcl-xl, and CaM were observed in Cd treatment group. Se ameliorated ΔΨm and [Ca(2+)]i for mitochondria function restoring, and Se was able to modulate the expression of relative genes. In conclusion, concurrent treatment with Se reduced the Cd-induced morphological changes and oxidative stress, ion disorder, and apoptosis, suggesting that the toxic effects of Cd on the chicken splenic lymphocytes were partly meliorated by Se.