CONCENTRATION AND COMPOSITION OF SERUM LIPOPROTEINS OF CHOLESTEROL-FED AND STILBESTROL-INJECTED BIRDS

Abstract

Most of the studies on serum lipoproteins have dealt with the concentrations of specific groups of these lipoproteins under a variety of experimental and clinical conditions.Recently we presented a method for measuring the lipide and protein compositions of four lipoprotein fractions that accounted for total serum lipoproteins (1).The separation of the fractions was based on the ultracentrifugal flotation technique as developed by Lindgren et al. (2), and each fraction was analyzed for protein, phospholipides, free and esterified cholesterol, and triglycerides.Although considerable variation in the concentrations of the various lipoprotein fractions was observed among the five species studied, namely, man, dog, rabbit, rat, and chicken, the composition of each lipoprotein fraction with respect to protein and various lipides was similar for the sera of these five species.The present report deals with the concentrations and the composition of the various lipoprotein fractions in the serum of birds that were either fed cholesterol-rich diets or injected with stilbestrol.The interest in these two experimental conditions lies in the fact that both induce arteriosclerosis in the bird and that the latter induced arterial degeneration even when the birds were fed diets low in lipide content (3, 4). EXPERIMENTALTreatment of Animals-2 month-old white Leghorn cockerels were divided into three groups.The first group, which served as controls, was fed Purina broiler chow ad l&turn, the second group was fed ad libitum a diet consisting of Purina broiler chow to which had been added 1 per cent cholesterol and 5 per cent Wesson oil, and the third group received, at bimonthly intervals, subcutaneous implants of 24 mg. of diethylstilbestrol and were fed Purina broiler chow ad l&itum.Nomenclature of Lipoprotein Fractions--In the interest of clarity and in order that the lipoproteins analyzed in this investigation may be compared