An estrogen receptor pathway regulates the telogen-anagen hair follicle transition and influences epidermal cell proliferation.

The study from October 29, 1996, demonstrated that the hair follicle cycle is influenced by an estrogen receptor pathway within the dermal papilla. Topical application of 17-beta-estradiol on mice skin arrested hair follicles in the telogen phase and inhibited hair growth, while the inactive form, 17-alpha-estradiol, had no effect. Conversely, treatment with the estrogen receptor antagonist ICI 182,780 prompted hair follicles to transition from telogen to anagen phase, initiating hair growth. Estrogen receptor expression in the dermal papilla was found to be highest during the telogen phase of the hair cycle. Additionally, the study showed that the number of proliferating epidermal cells, indicated by BrdUrd S-phase cells, varied with the hair follicle cycle, suggesting that factors from the anagen phase follicle affect epidermal cell proliferation.