Skin Reacts to UV Light Faster Than Thought, Study Finds

Discovery could hold key to new types of sunscreens, researchers say

URL of this page: http://www.nlm.nih.gov/medlineplus/news/fullstory_118301.html
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By Robert Preidt

Thursday, November 3, 2011 HealthDay Logo

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Sun Exposure

THURSDAY, Nov. 3 (HealthDay News) -- An ultraviolet receptor in the skin immediately senses and responds to UV light in order to protect against UV damage, researchers have found.

So, the tanning response in the skin occurs much more quickly than was previously known, the investigators noted in the study published in the Nov. 3 online edition of the journal Current Biology.

The discovery of this rapid biological response could lead to the development of new types of sunscreens, according to Elena Oancea and colleagues at Brown University.

The researchers found that exposure to UVA light causes pigment-producing cells in the skin to create melanin pigment in a process that involves calcium release. This response relies on rhodopsin, a light-sensitive protein that's also found in the eye's retina.

UVA light accounts for about 95 percent of the UV radiation on the Earth's surface, while UVB light makes up the other 5 percent. Melanin protects the skin by absorbing UV radiation and converting it to less harmful heat energy, the researchers explained in a journal news release.

"We found that human skin detects light using a mechanism similar to that used by the retina, on a timescale significantly faster than was previously known," said Oancea in the news release.

"Our findings show that both the eye and skin -- the only two organs constantly exposed to solar radiation -- use similar molecular mechanisms to decode light," Oancea added.

"We hypothesize that the early melanin production triggered by rhodopsin activation provides a first line of defense against ultraviolet light-induced damage," she said. "If this is the case, then this pathway and its protective capacity should be taken into consideration in the design and use of broad-spectrum sunscreens."

SOURCE: Current Biology, news release, Nov. 3, 2011

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