Effect of Feeding Xenobiotics on Serum High Density Lipoprotein and Apolipoprotein A-I in Rats

抄録

The effects on serum cholesterol level were examined in rats fed on various xenobiotics. The hypercholesterolemia induced by polychlorinated biphenyls (PCB) was characterized in rats, from which Iipoproteins were isolated by ultracentrifugation. A dietary addition of 0.03% PCB, 0. 3% chloretone, 0.1% aminopyrine, or 0.2% 2, 6-di-tert-butyl-β-cresol (BHT) resulted in a significant increase in serum cholesterol, although the chemical structure of each of these xenobiotics was different. The serum cholesterol level was markedly increased by one month of PCB feeding, the effect of PCB on the serum phospholipid level beingsimilar. The serum triglyceride level transiently increased within 7days of feeding with PCB diet. PCB feeding resulted in the elevation of all lipoproteins, including VLDL, LDL, HDL₁, and HDL₂, a marked increase being observed in HDL₁. Both HDL₁ and HDL₂ isolated from PCB-treated rats contained more apolipoprotein A-I (apo A-I) and less apo E than normal. VLDL isolated from PCB-treated rats had more cholesterol and apo E, but less apo C than that of the control animals. These data demonstrate that PCB feeding resulted in increased VLDL rich in cholesterol and apo E, and increased HDL rich in apo A-I. This experimentally induced hypercholesterolemia resulting in apo A-I-rich HDL would be a useful model for investigating the metabolism of apo-A-I and HDL.