Estradiol application to skin that has been protected from the sun appears to stimulate production of collagen in older men and women, according to a report released on September 15, 2008 in Archives of Dermatology, one of the JAMA/Archives journals. This effect may not be true for skin exposed to the sun.

When skin ages, it becomes fragile and shows compromised abilities to heal. Areas that are typically exposed to the sun, namely those not covered by clothing, have a prematurely old appearance due to exposure to ultraviolet rays from the sun — this is known as photo-aging. The biochemical features of both natural aging and photo-aging are similar, including a reduction in the protein collagen, which is a major structural component of the skin’s inner layer.

To investigate the effects of estradiol on these types of skin damage, Laure Rittié, Ph.D., and colleagues at the University of Michigan Medical School, Ann Arbor, examined a group of healthy volunteers with photodamaged skin, composed of 40 postmenopausal women and 30 men, with an average age of 75 years. Volunteers were treated with estradiol three times every other day for two weeks on both sun-protected areas near the hip and photodamaged skin on the forearm. A 4-millimeter tissue biopsy was sampled from each of these treatment areas 24 hours after the last treatment. Additionally, the subjects applied estradiol to their faces twice per day as a part of a moisturizing cream, and a corresponding 2-millimeter biopsy was taken from the crow’s-foot area near the eye before and 24 hours after the last treatment.

At the close of the treatment period, estradiol application was associated with increased levels in the sun-protected hip skin. This was true for women especially, but also true for men. The authors write: “Surprisingly, no significant changes in production were observed in women or men after two-week estradiol treatment of photo-aged forearm or face skin, despite similar expression of estrogen receptors [protein molecules to which estrogen binds] in aged and photo-aged skin.”

Estradiol is the major form of estrogen in the body and is especially present in women. The authors conclude that the lower levels of estrogen present in the body after menopause could be related to this phenomenon. “These findings suggest that menopause-associated estrogen decline is involved in reduced collagen production in sun-protected skin,” they say. “Because photo-aging 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 human skin in vivo.”

Induction of Collagen by Estradiol
Difference Between Sun-Protected and Photodamaged Human Skin In Vivo

Laure Rittié, PhD; Sewon Kang, MD; John J. Voorhees, MD; Gary J. Fisher, PhD
Arch Dermatol. 2008;144(9):1129-1140.
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Written by Anna Sophia McKenney