Effect of Stress from Cadmium Combined with Different Levels of Molybdenum on Serum Free Radical and Expression of Related Apoptosis Genes in Goat Livers

Abstract

Molybdenum (Mo) is an essential element for human beings and animals; however, high dietary intake of Mo can lead to adverse reactions. Cadmium (Cd) is one of the major transitional metals which have toxic effects in animals. The toxicity of simple Cd or Mo has been researched frequently. However, the toxicity of Mo combined with Cd was rarely studied. To investigate the toxicity of Mo combined with Cd in liver of goats, 36 Boer goats were randomly divided into four groups and assigned with one of the three oral treatments of CdCl2 (0.5mgkg(-1) Cd) and [(NH4)6Mo7O24·4H2O] (15mgkg(-1) Mo, group I; 30mgkg(-1) Mo, group II; 45mgkg(-1) Mo, group III), while the control group received deionized water. Blood samples were collected on days 0, 10, 20, 30, 40, and 50 to determine antioxidant indices in serum. In addition, liver tissues were collected on days 0, 25, and 50 for detecting the messenger RNA (mRNA) expression levels of Bcl-2 and Bax. Moreover, liver tissues at 50days were subjected to histopathological analysis with the optical microscope. The results revealed a significant increase (P<0.05 or P<0.01) in the levels of nitric oxide (NO), malonaldehyde (MDA), and the activity of nitrix oxide synthase (NOS) and a significant decline (P<0.05) in the activities of total superoxide dismutase (T-SOD) and total antioxidative capacity (T-AOC). The mRNA expression level of Bcl-2 was suppressed (P<0.05), while the expression of Bax was increased (P<0.05) in liver. The histopathological changes were observed in the liver of goats including a small amount of erythrocyte, the unclear structure of hepatic cord and hepatic sinusoid, granular degeneration, vacuolar degeneration, and steatosis. In conclusion, combined chronic toxicity of Cd with different levels of Mo might induce goat liver cell apoptosis and cause oxidative stress in serum, and it showed a possible synergistic relationship between the two elements.