17β-Estradiol and ICI-182780 regulate the hair follicle cycle in mice through an estrogen receptor-α pathway

The study demonstrated that topical application of estradiol (E(2)) at doses as low as 1 nmol inhibited hair growth in mice by preventing the transition from the resting phase (telogen) to the growth phase (anagen) of hair follicles. This effect was specific to E(2), as other steroids at similar doses had limited impact. The estrogen receptor (ER) antagonist ICI-182780 reversed the inhibitory effects of E(2) and independently promoted the telogen-to-anagen transition. The effects of both E(2) and ICI-182780 were localized to the application site, suggesting a direct action rather than a systemic one. The presence of ER-alpha, but not ER-beta, was confirmed in the skin, indicating that the ER-alpha pathway played a crucial role in regulating the hair follicle cycle.