Effect of Estrogen Dosage upon Plasma, Liver and Bile Lipids in Cholesterol-Fed Cockerels

Abstract

The effects of four dosages of conjugated equine estrogens (Premarin) on atherogenesis and on plasma, liver and bile lipids were studied in cockerels maintained on a high-fat, high-cholesterol diet. A lowering effect, not dose-dependent, occurred in plasma linoleic and linolenic acid. An augmentative effect, varying with dose, occurred in plasma phospholipids, plasma palmitic, stearic and oleic acids, liver total fat and thoracic atherosclerosis. A lowering, dose-dependent effect occurred in coronary atherosclerosis, plasma cholesterol-phospholipid ratio and plasma arachidic acid. A diphasic, dose-dependent, response occurred in: (1) plasma cholesterol (decrease at lowest dosage and increase at higher dosages); (2) bile cholesterol (increase at lower dosages and a decrease at higher dosages); (3) liver cholesterol (increase at lowest dose, and decrease at higher dosages); (4) plasma arachidonic acid (increase at lower and decrease at higher dosages). The mechanisms responsible for these changes are not clear but are under investigation.