Mechanisms Of Arsenic-induced Abnormal Blood Lipids Spectrum And The Influences Of Zinc In Rats

Objectives: To observe the changes in blood lipids spectrum in arsenic-poisoning rats and explore it's mechanisms and the influences of zinc as well.Methods: 56 young male rats were divided into 8 groups at random. The rats were exposed to arsenic at a gradient doses for 6 weeks respectively. Then the rats were sacrificed and the serum obtained. 1. TG, TC, LDL-C and HDL-C were detected with enzymological method. 2. ApoA-1 and apoB were measured with immunotransmiting assay. 3. LDL-R and HDL-R were assayed with immunohistochemistry. 4. The changes in histology of liver was observed under light and electronic microscope.Results: 1. Compared with these of the control group, the content of TG, LDL-C,TC and apoB in serum of arensic-poisoning rats were decreased remarkably and the HDL-C and ApoA-1 increased obviously with the increase in the dose of arensic. In comparesion with that for the control group, the change of high dose group was statistically significant. 2.The levels of TG,TC,LDL-C and apoB in zinc-exposed rats were lowered and HDL-C and apoA-1 elevated. Relative to those for the control group, the concentrations of TC,LDL-C,HDL-C and apoB in high dose group were altered statistically significant. 3.The concentrations of TG,TC,LDL-C,apoB and HDL-C, apoA-1 were raised and diminished respectively inl/5LD50 arsenic-poisoning group after being exposed to zinc. In contrast to those for 1/5 LD50 arsenic-poisoning group, the changes in content of TG, LDL-C,HDL-C for 20 physiological dose zinc group was obvious. As opposed to those for the control group, the change came close to thelevels of contral group. 4.The expressions of LDL-R and HDL-R in arsenic-poisoning rats were increased and decreaed respectively with the increases in arsenic dose.Compared with the control group, the change in 1/5 LD50 arsenic-poisoning group was substantial. The expressions of LDL-R and HDL-R were increased and decreased respectively with the coexposure to zinc. Compared with 1/5 LD50 arsenic-poisoning group, the changes was obvious in zinc -treatment group. 5.Under light microscope in arsenic-poisoning groups, cells with lipid droplet and acidopilicity were seen. After being exposed to zinc, the lipid droplet and acidopilicity were decreased obviously. Ultrastructure change were as follows, there were plenty of lipid droplets inside the liver cells of arsenic-poisoning rats.Mitochondria and rough endoplasmic reticulum were swollen and the membrane damaged.Ribosome fallen off from rough endoplasmic reticulum.The changes were reversed almost to control level in zinc treatment group.Conclusions: Arsenic is able to influence the lipids metabolism. The serum lipid spectrum was characteristicsly affected, the feature of serum lipid spectrum is "higher HDL-C and lower TG, TC, LDL-C".And those are probably related to the expression of HDL-R and LDL-R, the concentration of lipid Apo protein and the damage of the ultratructure of liver cell. Zinc can ameliorate the change of blood lipid spectrum. The mechanisms are probably that zinc can regulate the receptor of liver cell for HDL-C and LDL-C, compete with arsenic for -SH binding and precipitate the excretion of arsenic.