Applying the hormone estradiol to skin protected from the sun
appears to stimulate production of the protein collagen in older men
and women, according to a report in the September issue of
Archives of Dermatology, one of the
JAMA/Archives journals. However, it may not have the same effect on sun-exposed skin, such as the face or arms.
skin ages, its function is reduced, it becomes more fragile and wound
healing is compromised, according to background information in the
article. On areas of the body that are typically not covered by
clothing, long-term exposure to the sun's ultraviolet rays causes skin
to look prematurely old, a process known as photo-aging. Natural aging
and photo-aging share biochemical features, including a reduction in
collagen, the major protein that forms the structure of skin's inner
Laure Rittié, Ph.D., and colleagues at the University of
Michigan Medical School, Ann Arbor, recruited 70 healthy volunteers (40
postmenopausal women and 30 men, average age 75 years) with
photodamaged skin. For two weeks, volunteers were treated with
estradiol three times every other day both on sun-protected areas near
the hip and photodamaged skin on the forearm; a 4-millimeter biopsy
(tissue sample) was taken from each treatment area 24 hours after the
last treatment. Participants also applied estradiol, incorporated into
moisturizing cream, to their faces twice per day during the two weeks.
A 2-millimeter biopsy was taken from the crow's-foot area near the eye
before and 24 hours after the last treatment.
After the two-week
treatment period, applying estradiol to the sun-protected hip skin
increased levels of collagen and other compounds that promote its
production in the women and, to a lesser extent, in the men.
"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," the
"These findings suggest that menopause-associated
estrogen decline is involved in reduced collagen production in
sun-protected skin," the authors write. "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."