The Co-induced Effects Of Molybdenum And Cadmium On The A Ntioxidant Function And The MRNA Expression Levels Of Related Apoptosis Genes In Duck Kidneys

This study was designed to investigate the effects co-induced by molybdenum(Mo)and cadmium(Cd) on antioxidant function in serum, the mRNA expression levels of related genes of kidneys in ducks. 360 ducks in 11-day-old were divided into six groups:control group, low dietary of Mo group(LMo group), high dietary of Mo group(HMo group), Cd group, low dietary of Mo + Cd group(LMo+Cd group) and high dietary of Mo+ Cd group(HMo+Cd group). Ducks in control group were fed with basal diet, diet of the experimental groups were added with 15 mg/kg Mo, 100 mg/kg Mo, 4mg/kg Cd, 15 mg/kg Mo + 4 mg/kg Cd, 100 mg/kg Mo + 4 mg/kg Cd, respectively. Ammonium heptamolybdate([(NH4)6Mo7O24·4H2O]) and cadmium sulphate(3CdSO4·8H2O) were selected as the sources of Mo and Cd. The time span for experiment was 120 d. After treated for 30, 60, 90,120 days, blood and kidneys of ten ducks in each group were collected for determining the antioxidant activity indexes in the kidney mitochondria and serum and the expression of related apoptosis genes. In addition, kidney tissues at 120 d were subjected to histopathological analysis with the optical microscope. The results are shown as followings:1. At 60 d, the malondialdehyde(MDA) level and nitric oxide synthase(NOS)activity in experimental groups except LMo group in kidney mitochondria increased significantly(P<0.05 or P<0.01) while the total antioxidative capacity(T-AOC) and the activity of xanthine oxidase(XOD) decreased significantly(P<0.05 or P<0.01) as compared to control groups. There were significant difference(P<0.05 or P<0.01) between combined groups and single treated groups;2. The T-AOC and activities of catalase(CAT), glutathione reductase(GSH-Px),superoxide dismutase(SOD), XOD, succinodehydrogenase(SDH) in serum of experimental groups except LMo group decreased significantly(P<0.05 or P<0.01) while the MDA level and NOS activity increased significantly(P<0.05 or P<0.01) as compared to control groups. Difference between combined groups and single treated groups was significant(P<0.05 or P<0.01);3. At 120 d, kidney tissue was damaged with varying degrees of ultrastructure changes. Membrane was damaged, the number of mitochondria was reduced, vacuoles,crest fracture, nuclear condensation and lysosomes were visible in cytoplasm, high-density electron donor were observed, the nuclear membrane is not clear;4. At 60 d and 120 d, the mRNA expression levels of Bak-1 and Caspase-3 in experimental groups except LMo group increased significantly(P<0.05 or P<0.01) while the mRNA expression level of Bcl-2 decreased significantly(P<0.05 or P<0.01) as compared to control groups. Difference between combined groups and single treated groups was significant(P<0.05 or P<0.01).The combination of Mo and Cd induced oxidative stress in kidney mitochondria and se rum, leading to damage on kidney cells and changes of renal ultrasture.Meanwhile, the mR NA expression levels of Bak-1 and Caspase-3 were upregulated while Bcl-2 was downregu lated. There was a dose-effect relationship between them. The co-induction of Mo and Cd may have synergistic effect on renal toxicity in ducks.