Research Bares Sunless Tanning Method : Dermatology: Experimental hormone treatment might help people who burn easily as well as offer a hedge against the peril of ozone layer depletion.

Researchers in the heart of the country’s skin-cancer belt say they have found a way to make people tan without sun--a finding some say could prove not only a triumph of vanity over the elements but also a hedge against depletion of the ozone layer.

The University of Arizona researchers reported today that injections of a synthetic form of a hormone that enables frogs and lizards to change color caused deep tanning in white men without the need for potentially harmful exposure to ultraviolet radiation.

The experimental treatment might one day be useful for people who tan poorly and burn easily, leaving them at high risk for skin cancer, and perhaps for many others as pollution continues to damage the Earth’s protective ozone layer, the researchers said.

“As the ozone layer is depleted (exposing people to harmful ultraviolet radiation), this may become useful in many more individuals, even those who tan moderately well,” they speculated in the report of their findings in the Journal of the American Medical Assn.

The report was received Tuesday with curiosity and some caution by dermatologists. As did the authors of the study, some dermatologists pointed out that the results are preliminary and that nothing is known about long-term effects of the hormone’s use.

“These kinds of substances have a lot of different activities (in the body),” said Dr. Anita Highton, director of the UCLA Dermatology Center. “ . . . this might be useful later on, but you have to make sure that, if it’s for widespread use, it’s not doing any harm.”

Excessive exposure to the sun is one of the greatest risk factors for skin cancer, which strikes primarily fair-skinned people. The ozone layer is thought to protect people against the sun’s ultraviolet B rays, which have been linked to skin cancer and sunburn.

More than 600,000 cases of skin cancer are diagnosed in the United States each year, most of them highly curable, basal cell or squamous cell cancers. The incidence of melanoma, the most serious and sometimes deadly form of skin cancer, is increasing at a rate of 4% a year.

In the study, the researchers used a synthetic, “super-potent” form of a hormone known as alpha-melanotropin. In some animals, though not humans, the hormone is known to regulate skin coloration by acting on cells that produce the protective pigment, melanin.

The hormone appears to have other functions in the body, according to an editorial accompanying the paper. Among other things, it appears to transmit nerve impulses in the central nervous system and to have a role in immune response.

Half of the 28 men in the study received 10 injections of the hormone over a two-week period; the control group got shots of a saline solution. They were then followed for seven weeks, their skin color measured with a device capable of recognizing subtle differences.

By the end of the third week, those who had received the hormone had begun to tan. Their tans peaked at the end of the fifth week. The tans lasted three to four weeks and had faded by the end of the study period. The control group did not tan.

“Many of the people were accused (by acquaintances) of taking a very long vacation,” said Robert T. Dorr, an associate professor of pharmacology and medicine at the Arizona Cancer Center at the University of Arizona. “It was a very dark, evenly distributed tan.”

As for side-effects, the researchers said most of the men who received the hormone shots “experienced a mild flushing reaction” immediately after the first few shots. Many also reported vague gastro-intestinal discomfort for five to 15 minutes after the shots.

While the drug remains experimental, the researchers suggested it might eventually be used to protect light-skinned people against skin cancer. By stimulating production of the protective pigment, melanin, it might trigger the beneficial effects of tanning without the harm done by sun.

In addition, it could protect others who simply like being tanned.

“Anything that got people out of the sun could be potentially helpful,” said Dorr. “Even though having a tan is cosmetic, there are a lot of people interested in having that cosmetic effect. If you could do that without going in the sun, that would be an advantage.”

Dr. Darrell Rigel, a dermatologist at New York University, was optimistic about the findings, predicting it might eventually be possible to get the protective effect of tanning without the initial damage.

Highton, however, was more skeptical.

“My feeling, right off the bat, is that we’ve spent a long time trying to convince people not to want to get tan,” she said. “If this becomes widespread, let’s just say, I think that we could go back to square one.”