Pharmacologically induced hypolipidemia. The ethinyl estradiol-treated rat.

The aim of this study was to examine in detail the lipid and apoprotein concentrations in the serum of rats treated with pharmacologic doses (5 mg/kg/d for 5 d) of the synthetic estrogen derivative ethinyl estradiol. The results show that in rats, estrogen-induced hypolipidemia is associated with a nearly complete absence of the lipid and protein moieties normally found in d less than 1.21 fraction of serum. Quantitation of specific apolipoproteins by immunoelectrophoresis show that most apolipoproteins are decreased by more than 90% in the serum of estrogen-treated rats. In contrast to the changes in d less than 1.21 lipoproteins, estrogen treatment only slightly reduced serum phospholipid concentrations (by only 10%) and caused no change in the concentration of serum albumin. The results show that the ethinyl estradiol-treated rat is an excellent model of drug-induced hypolipidemia.