THE EFFECTS OF HYPOPHYSECTOMY, ADRENALECTOMY AND OF THIOURACIL FEEDING ON THE CYTOLOGY OF BROWN ADIPOSE TISSUE1

Abstract

In rats and mice after hypophysectomy or adrenalectomy the brown adipose tissue rapidly becomes depleted of its stored lipids. The fat droplets in the cells are transiently increased in number while, at the same time, they are gradually reduced in size. The brown fat is finally reduced to lobules of coarsely granular epithelioid cells which appear to contain little or no lipid. Daily injns. of adrenocorticotrophin prevent the development of these cytological changes in the brown fat of hypo-physectomized mice. It is concluded, therefore, that the maintenance of the normal complement of lipid in brown adipose tissue depends on the functional integrity of the adrenal cortex. The pituitary apparently exercises its effects on this tissue through its regulation of adrenal cortical activity''. Prolonged ingestion of thiouracil by rats results in histological alterations in their brown fat which are similar to those seen after hypophysectomy or adrenalectomy. These changes develop slowly and may depend upon the gradual atrophy of the adrenal cortex which results from chronic admn. of thiouracil.