The binding of topically applied glucocorticoids to rat skin.

The epidermis of rat skin was shown to be the major site of accumulation of label after the topical application of [3H]-cortisol, [3H]-corticosterone and [3H]-triamcinolone acetonide. However, incubation of the skin in vitro in a way which ensured contact only between the dermal side of the skin and the steroid showed preferential accumulation of label from [3H]-cortisol and [3H]-corticosterone in the epidermis whereas label from [3H]-triamcinolone acetonide appeared evenly spread in the dermis and epidermis. The affinity of corticosterone to soluble proteins in skin homogenates was greater than that of cortisol as measured by displacement binding and correspondingly glucose uptake into the skin in vitro was inhibited for 18 hr after a single application of corticosterone but was not inhibited by cortisol.