Effect of estrogen dosage upon plasma, liver and bile lipids in cholesterol-fed cockerels.

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 dosedependent, 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 cholesterolphospholipid 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. ADDITIONAL