Reduced collagen content is one of the features of aging skin, leading to a loss in strength and resilience, and an overwhelming number of anti-aging ingredients are designed to stimulate collagen synthesis in the dermis.
Although previous scientific studies have highlighted a possible role estrogens may play in collagen levels in aged skin, this new research suggests there may be significant differences between the effects of estrogens in skin that has been protected from sunlight and photoaged skin.
Estradiol has little effect on photoaged skin
The researchers, led by Dr Gary Fisher from the University of Michigan Medical School’s Department of Dermatology, found that applying estradiol, an estrogen, to photoaged skin, both on the forearms and the face, had little effect on the levels of collagen production in the skin.
During the study postmenopausal women applied various doses of estradiol to hip skin (representing naturally rather than photoaged skin) which lead to a dose dependent increase in procollagen I and III mRNA levels and in procollagen I protein.
Fisher and the team also noted that topical estradiol also increased procollagen expression in the hip skin of age-matched males, but to a lesser extent.
However, following a similar procedure but applying the estradiol to the forearm and the face did not significantly alter procollagen I or III mRNA levels.
The researchers did suggest that extending the experimental period may have had an effect on the results.
“It is possible that a treatment time of longer than 2 weeks would have demonstrated effects similar to those in sun-protected skin. Additional studies will be necessary to test this possibility,” write the authors.
Indirect pathway
Nevertheless, the authors concluded that the results suggest that estradiol must affect collagen levels indirectly ‘and that photoaged skin lacks an essential component to the estrogen-mediated collagen response’.
“Because photoaging is superimposed on natural aging in sun-exposed areas of the skin, our results suggest that alterations induced by long term sun exposure hinder the ability of topical estradiol to stimulate collagen production in aged humans skin in vivo” they added.
Source: Archives of DermatologyVolume 144, Number 9Induction of Collagen by Estradiol – Difference Between Sun-Protected and Photodamaged Human Skin In VivoLaure Rittié, Sewon Kang, John J Voorhees, Gary J Fisher