University of Pennsylvania researchers have uncovered new pathways that control skin lightening and tanning. The knowledge could lead to a novel class of therapeutics, which is especially important given the limited options for safe and effective treatment of pigmentation disorders, according to a new study.1
âAlthough we have always assumed that there was some connection between pregnancy âhormonesâ and pigmentation, the specific hormones and mechanism through which they regulate pigment has never been defined,â says the studyâs senior author Todd W. Ridky, M.D., Ph.D., assistant professor of dermatology at the Perelman School of Medicine at the University of Pennsylvania.
Dr. Ridky and colleagues exposed human melanocytes to estrogen levels generally seen during pregnancy. The cells responded by increasing melanin production. Ethinyl estradiol, which is commonly used in birth control pills, had a similar effect, as did tamoxifen, which usually blocks estrogenâs effects.
The melanin content of the cells increased 200% to 300% after four days.
When melanocytes were exposed to progesterone, melanin production decreased.
With further testing, the researchers found that melanocytes express receptors not previously studied: a separate, non-classical, estrogen receptor, GPER, as well as a non-classical progesterone receptor, PAQR7. They confirmed those receptors are responsible for the skin pigment effects.
In the lab, they tested new compounds that alter skin pigmentation based on the finding that the receptorsâ activity was activated or inhibited by synthetic estrogen or progesterone analogs, which do not bind to estrogen or progestin receptors.
The researchers purified the selective GPER-activating compound, creating a cream, and applied it to miceâs ears. The treatment increased melanin levels by about 60% during three weeks, according to a press release.
These compounds will have to go through the FDA and clinical trials before theyâre made available to dermatologists, according to Dr. Ridky.
âThere is a potential role for these agents in post-inflammatory hyper and hypo-pigmentation, melasma, and possibly vitiligo. These new agents also will also likely fill a cosmetic need. The new potential tanning agents darken skin without UV damage â a major improvement over tanning beds and sitting out in the sun,â he says.