Abstract
Summary
The effects of high and low concentrations of circulating thyroid hormone on the total cholesterol contents of plasma and liver, and on aortic cholesterol deposition were studied in rats fed a diet either low or high in cholesterol.
In the hyperthyroid groups, the plasma cholesterol values were normal or slightly lower, and to some extent independent of the cholesterol content of the diet; in the thiouracil-treated series, the plasma cholesterol levels were significantly increased, reaching the highest values in the rats fed the high cholesterol diet.
The liver cholesterol concentrations were normal in the animals not supplemented with dietary cholesterol, and strikingly increased in all groups fed the high cholesterol diet, to a great extent independently of the concentrations of circulating thyroid hormone.
The aorta appeared macroscopically normal in all groups; microscopic examination revealed, in the cholestero-fed animals, a moderate cholesterol deposition, diffuse in the hyperthyroid rats, and focal in the thiouracil fed animals. Isolated cases of early atheromata and widespread fatty infiltration were observed in the rats fed thyroid and cholesterol, and in both groups treated with thiouracil.
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