Glucocorticoids and lactation. In vitro metabolism of glucocorticoids by rat mammary glands.

In view of: 1. the extensive in vitro 21-acylation of [3H]corticosterone by rat mammary glands, especially during lactation; 2. the accumulation of 21-acyl [3H]corticosterone as the predominant form of the hormone in the alveolar nuclear fraction with which it is strongly associated; 3. the results of a systematic study of the influence of acylation per se of corticosterone and dexamethasone on their binding affinities for specific glucocorticoid-binding proteins; and 4. the extensive metabolic acylation, similarly, of adrenocortical hormones other than corticosterone, it is suggested that the acylation of glucocorticoid by the mammary gland may serve to modulate the biological action of the hormone on this target organ, and indirectly influence the flow of glucocorticoid from plasma to milk.