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Childbirth Hormone Yields Secrets

Researchers find more receptors and more roles for relaxin

THURSDAY, Jan. 24, 2002 (HealthDayNews) -- Researchers say they have identified two key molecules that activate relaxin, a childbirth hormone that turns out to be a lot more important than was originally thought.

Relaxin got its name because it was first identified as a hormone that softens the cervix in preparation for delivery. Now a team headed by Aaron J. W. Hsueh, a research scientist at the Stanford University School of Medicine, reports it has found two receptor molecules through which relaxin acts on a number of organs throughout the body.

"The wide and divergent distribution of the two relaxin receptors implicates their roles in reproductive, brain, renal, cardiovascular and other functions," says a report on the discovery in tomorrow's issue of Science.

It's "a very significant finding," says Laura Goldsmith, professor of obstetrics, gynecology and women's health at New Jersey Medical School. She has been researching relaxin for several years.

"A receptor gives a hormone the ability to act upon a cell," Goldsmith explains. "Hormones communicate information from one cell to another. That communication requires not only the hormone, but also a receptive molecule. Frequently, diseases are caused not by a deficiency of a molecule, but by improper receptor amount or function."

Research on relaxin has been held back "because we have not been able to understand exactly how it affects cells," Goldsmith says. Identifying the relaxin receptors "also gives us the potential to identify abnormalities of the receptors," she adds.

"My laboratory has information that suggests that high levels of relaxin are associated with prematurity," she says. "Without knowledge of the receptor, we couldn't understand what was happening."

The finding opens several lines of research, Hsueh says. One is the study of relaxin-like molecules that have been detected in the body. However, he will also be working on research of relaxin itself.

"We will be mostly focused on the gonads and reproductive tract," he says. "We will also be looking at cardiac function and skin."

Studies suggest relaxin might play a role in developing treatments for scleroderma, a condition in which the body's immune system mistakenly attacks the skin, kidneys, lungs, heart and other organs, Hsueh says.

"This helps us complete a story that began many years ago," Goldsmith says. "There have been thoughts and hypotheses about the function of relaxin, but we were not able to determine it because we did not have the receptor. This is a useful piece of information for all of us studying relaxin in humans."

What To Do

Basic research of this sort doesn't have an immediate medical application, but it promises a payoff in the future.

Information about a meeting that was held on relaxin is available from the University of Melbourne in Australia. You can also try

SOURCES: Interviews with Aaron J. W. Hsueh, Ph.D, senior research scientist, Stanford University School of Medicine, Palo Alto, Calif.; Laura Goldsmith, Ph.D, professor of obstetrics, gynecology and human health, New Jersey Medical School, Newark, N.J.; Jan. 25, 2002, Science
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