[Effect of thyroidectomy and subsequent L-thyroxine administration on the content of various lipids in the organs of rats of different age].

Total lipid, phospholipid and cholesterol content in the tissues of the liver, myocardium, skeletal muscle, intestine and the blood plasma was studied on three groups of rats (control, thyroidectomized, and thyroidectomized to which l-thyroxin was administered); the animals were aged 2, 6 months and 2 years. All the indices studied increased in the tissues and the blood of intact animals with the advance of age at different percentage ratio. As to thyroidectomized animals, cholesterol and phospholipid content increased in all the organs under study at the age of 2 and 6 months, and fell in the old ones. Total lipid content rose at the age of two months and decreased in the sexually mature and old rats. In the thyroidectomized animals to which l-thyroxin was administered cholesterol and total lipid content rose in all the tissues, excluding the blood plasma, whereas phospholipid content reduced in all the organs under study.