THE LIPOTROPIC ACTION OF COLD: 1. THE INFLUENCE OF COLD AND CHOLINE DEFICIENCY ON LIVER LIPIDS OF RATS AT DIFFERENT INTAKES OF DIETARY METHIONINE

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Abstract
The effect of cold exposure and choline deficiency on the levels of liver lipids of male albino rats was studied at four dietary intakes of methionine (20–100 mg per rat per day). After exposure of the animals to cold (2–3 °C) for a 10-day period, the liver lipids were analyzed for total and free cholesterol, phospholipid, and triglyceride.In choline-fed animals, cold exposure did not affect triglyceride or total cholesterol levels but elevated phospholipid and free cholesterol and decreased ester cholesterol. The increase in phospholipid levels occurred at all methionine intakes with the changes in the cholesterol fractions occurring only at methionine intakes >40 mg per day.In choline-deficient rats, there was evidence that the lipotropic action of cold exposure was related to dietary methionine intake. At methionine intakes <60 mg per rat per day, fatty infiltration of the livers of the choline-deficient cold-exposed rats occurred, as evidenced by the accumulation of triglyceride and ester cholesterol. Concomitantly, phospholipid levels decreased. The data suggest that cold increases the capacity of the animal to synthesize choline from endogenous sources.