Mechanisms Of Liver And Kidney Impairment Caused By High Molybdenum In Chickens

The experiment was conducted with the objective of examining the effect of dietary high molybdenum on liver and kidney in chickens by the methods of experimental pathology and flow cytometry (FCM).300 one-day-old avian broilers were randomly divided into four groups, and fed on diets as follows:Control diet (Mo 13mg/kg) and high molybdenum diets (Mo 500 mg/kg, high molybdenum groupâ… ; Mo 1000 mg/kg, high molybdenum groupâ…¡; Mo 1500 mg/kg, high molybdenum groupâ…¢) for 6 weeks. The hepatic superoxide dismutase (SOD), glutathion peroxidase (GSH-Px) and xanthine oxidase (XOD) activities were lower (P<0.01), and the malondialdehyde (MDA) contents were higher(P<0.01) in high Mo groupsâ…¡andâ…¢than in control group. Changes of the above mentioned enzymes activities and MDA contents in serum were consistent with those of liver. Pathologically, hepatocytes in high Mo groups showed granular degeneration and vacuolar degeneration. The weight of body and liver was significantly decreased (P<0.05 or P<0.01), and the relative weight of liver was significantly increased in high molybdenum groupâ…¡andâ…¢when compared with control group (P<0.05 or P<0.01). Ultrastructurally, endoplasmic reticulums of hepatocyte were dilated and the mitochondria were swelled or with its crista broken. By FCM, the G0/G1 phase was significantly increased (P<0.01), and S phase, G2+M phase and PI (Proliferating index) significantly decreased (P<0.01) in high molybdenum groupsâ…¡andâ…¢during this experiment. The apoptotic rate was higher in high molybdenum groupâ…¡andâ…¢than that in control group at 14,28 and 42 days of age (P<0.01).Compared with those of control group, the renal glutathion peroxidase (GSH-Px) and superoxide dismutase (SOD) activities were lower (P<0.01), and the malondialdehyde (MDA) contents were higher (P<0.01) in high Mo groupsâ…¡andâ…¢than in control group. Changes of the above mentioned enzymes activities and MDA contents in serum were consistent with those of kidney. At the same time, the serum creatinine and serum uric acid contents were much higher in high Mo groupsâ…¡andâ…¢than in control group (P<0.05 or P<0.01). The renal tubule epithelial cells showed swelling, granular degeneration and vacuolar degeneration in high Mo groups. Ultrastructurally, endoplasmic reticulum and nuclear membrane expanded, mitochondrial were swelling or shrinked with increased in electron density, and myelin-like structure in the microvilli were appeared in renal tubule epithelial cells in high Mo groupsâ…¢. The relative weight of kidney were higher (P<0.05 or P<0.01),and the G0/G1 phase of cell cycle of renal cell was lower, S phase and the PI (Proliferating index) was higher in high molybdenum groupsâ…¡andâ…¢than that in control group(P<0.01).The percentage of renal cell apoptosis was increased in high molybdenum groupsâ…¡andâ…¢when compared with that of control group(P<0.01).The TUNEL staining was consistent with the result of FCM.Immunohistochemistry test showed that there were increased frequencies of positive cells in Bax detection, and decreased Bcl-2 protein containing in high molybdenum groupsâ…¡andâ…¢. The results showed that dietary molybdenum in excess of 1000mg/kg impaired hepatic antioxydic function, resulted multiplication capacity restrained of hepatocyte and increased apoptotic, and the liver function was depressed. Dietary molybdenum in excess of 1000mg/kg also caused renal pathological injury and decreased antioxidant enzymes activities, and impaired the progression of renal cells from S phase to G2+M phase obviously and induced renal cell apoptosis. The renal function was finally injuried.