"ERβ knockout mice display accelerated catagen development, along with an increase in the number of apoptotic hair follicle keratinocytes (28). This suggests that, contrary to previous working hypotheses (274), ERβ does indeed play a significant role in murine hair growth control: whereas the catagen-promoting properties of E2 are mediated via ERα, ERβ may mainly function as a silencer of ERα action in hair biology (28). Nevertheless, ERα is thought to serve as the predominant ER in the hair follicle of animals (31, 233, 254)."
"Estrogens have been used for topical treatment of hair diseases for more than half a century (284) and constitute a firm staple of management strategies for female pattern androgenetic alopecia in central Europe (88). Orentreich observed in 1969 a decrease in daily effluvium during therapy with systemic estrogens (285), which were reported to increase the proliferation rate, slow down differentiation, and, thus, postpone telogen effluvium (286)."
"progesterone receptor, prolactin, and lactoferrin are examples of relevant target genes in the pilosebaceous unit with consensus EREs (263–265)."
"The number of genes that carry an ERE, whose transcription is known to be altered by E2 stimulation, is very large (294) (Table 3). Together with the fact that E2 modifies androgen metabolism and vice versa (250, 251) and the intriguing cross talk examples discussed above, this already renders the number of potential signaling cross talks and cross-modulation events that may impact how E2 can alter the growth of a given hair follicle in a defined gender and location daunting. This gets even more complicated if one enters additional recent findings into the equation. Suffice it here to list just two selected examples of this added level of complexity: possible cross talks between E2/ER and intrafollicularly generated hormones, such as melatonin (53) and prolactin (8, 9)."