Abstract
The effects of fasting and thyroid function on changes in liver lipid content and serum free fatty acid (FFA) concentration in adrenalectomized (ADX) rats fed a high-fat diet were examined and compared with those in ADX rats fed a high-carbohydrate diet.
Liver lipid content in rats fed the high-fat diet was unchanged by fasting regardless of adrenal status, whereas lipid accumulation in the liver caused by fasting occurred in rats fed the high-carbohydrate diet. The lipid content of the liver was slightly decreased by adrenalectomy and restored by cortisone administration. Response of liver lipids to thyroid function was observed in cortisone treated ADX (ADX-C) rats and the lipid content of the liver during fasting was highest in hypothyroid rats. Serum FFA levels in rats fed the high-fat diet were increased by fasting, but no relation was observed between serum FFA levels during fasting and adrenal function. Rats given a sham operation showed responses of serum FFA to thyroid function and the highest FFA level was found in hyperthyroid rats, whereas ADX and ADX-C rats did not show such responses. These findings suggest that the effects of fasting and thyroid function might differ in the regulation of liver lipid accumulation, and that glucocorticoid action might be related to the mechanism associated with thyroid function.
