Effects Of High-dose Vitamin D Injection On Cadmium Toxicity In Mice

Aim To investigate whether high-dose vitamin D3 injection can ameliorate the cadmium toxicity in mice and the mechanisms underline the effects.Methods The study contains there parts:First, to establish a mouse model of cadmium poisoning and study the effects of high-dose vitamin D on bone toxicity of cadmium : Using 0 mg/kg, 1 mg/kg, 3 mg/kg, 5 mg/kg, 7 mg/kg dose of Cd Cl2, the mice were injected intraperitoneally twice a week for 4 weeks. After 5 weeks’ treatment, the body weight, organ coefficient and HE staining was performed. The mice were divided into three groups, vehicle group, Cd Cl2 group(2 mg/kg twice per week, in 2-5 weeks), Cd Cl2+VD group(1000 IU/w, in 1-6 weeks). After 6 weeks’ treatment, the body weight, organ coefficient, bone wet weight, bone length, HE staining was performed on mice. BMD analysis and three-dimensional reconstruction of bone were studied. Second, study the effects of vitamin D injection on Cadmium-induced bone toxicity in mice : The mice were divided into vehicle group, Cd Cl2(1 mg/kg twice per week, in 2-5 weeks), Cd Cl2+ALN(positive control, 0.21mg/kg/w, in 2-6 weeks), Cd Cl2+VD(125 IU/w, in 1-6 weeks), Cd Cl2+ALN+VD groups. After 6 weeks’ treatment, body weight and organ coefficient, wet weight of bone, bone length; HE staining was studied. Micro-CT was used to analyse BMD and three-dimensional reconstruction. Third, study the effects of vitamin D injection on cadmium-induced immunotoxicity: The mice were divided into vehicle group, Cd Cl2 group(1 mg/kg twice per week, in 2-5 weeks) and Cd Cl2+VD(125 IU/w, in 1-6 weeks)groups. After 6 weeks’ treatment, the body weight, white blood cell count and classification of counting and organ coefficient were studied. The peritoneal macrophage phagocytosis and spleen and thymus T lymphocyte subsets were studied by flow cytometer.Results(1) The body weight was inhibited in the cadmium groups with the dose of 3 mg/kg, 5 mg/kg and 7 mg/kg. With the increase of cadmium doses, liver and spleen organ coefficient increases, kidney and bone damage gradually serious; Compared with the control group, the liver coefficient and spleen coefficient of Cd Cl2 group was significantly larger, and the wet weight of right bone was significantly lighter than the right; Compared with the Cd Cl2 group, Vitamin D injection significantly decreased liver coefficient and bone mass(P<0.05), the damages of kidney and bone had improveed; No significant differences in BMD was observed in groups(P>0.05).(2) After the injection of cadmium, the body weight of mice had a slower growth in the second week compared with the control group(P <0.05); Spleen coefficient of the group with the injection of cadmium was significantly larger than the control group(P<0.05),and the liver coefficient(except VD group) was larger than the control group(P<0.05); Vitamin D alone intervention, Vitamin D and ALN joint intervention both significantly improved the renal tubular epithelial cells shedding, necrosis; The trabecular numbers, shapes and arrangements had improved after the Vitamin D and ALN alone intervention, while no synergistic phenomenon was observed after ALN and Vitamin D joint interventions, but the newborn trabecular was increased.(3) The liver, spleen coefficient significantly increased in the Cd Cl2 group compared with the control group. The phagocytic rate, phagocytic index and the percentage of spleen CD4+/CD8+ also decreased significantly in Cd Cl2 group(P<0.05). Vitamin D injection significantly increased peritoneal macrophage phagocytosis and failed to ameliorate other immunological indices.Conclusion1, Low-dose cadmium can damage the organs and bone in mice and high-dose vitamin D(1000 IU/w) injection did not significantly improve the bone toxicity of cadmium induced in mice.2, Relatively high-dose vitamin D(125 IU/w) injection improved bone toxicity and kidney damage in cadmium poisoning mouse model.3, Cadmium significantly influences the immune function of mice and relatively high-dose vitamin D(125 IU/w) injection significantly improved Cd induced immunotoxicity.