- The Washington Times - Thursday, August 8, 2002

Researchers in Oregon and London say they have discovered a hormone that helps people eat less by making them feel full at mealtime.

The scientists made their discovery in a small-sample study published this week in the British science journal Nature.

In the study, 12 Londoners of normal weight six men and six women were injected, for 30 minutes, either with the hormone, known as PPY 3-36, or with a placebo salt solution. Two hours later, the subjects partook of a large buffet.

The study found that the subjects given the hormone, nicknamed the "third helping hormone," which is secreted by cells lining the intestines, ate about a third less than their counterparts in the control group.

What's more, over the next 12 hours, those injected with the hormone reported feeling less hungry than the control group did, and they did not make up the calories they missed by snacking. The scientists determined that was because levels of the hormone rose after meals and remained high between meals.

"This research very likely is critically important," Dr. Arthur Frank, medical director of George Washington University's Weight Management Program, said yesterday in an interview.

"Eating is not merely a matter of choice. Most of eating is driven by the brain. The intensity of control by the brain [over appetite] is hard to override. That's why dieting is so difficult," he said. "These studies are taking apart the complex mechanisms the brain uses in regulating how much we eat."

Steven Bloom of the Imperial College of London, senior author of the Nature report, said the hormone infusion before the buffet was "sort of a false meal" for those who received it.

"The brain was fooled into thinking it had already eaten," he told the Associated Press.

The researchers who participated in the study were divided on whether the PPY 3-36 hormone itself someday would emerge as an effective tool in fighting obesity. Mr. Bloom says a drug based on elevating levels of the PPY 3-36 hormone may cut overeating and between-meal snacking.

Another researcher, Michael Cowley, assistant scientist in the division of neuroscience at the National Primate Research Center in Beaverton, Ore., said yesterday in a telephone interview: "I'm hopeful this will lead to a therapy for obesity. But, at this point, it's very premature."

The "important part" of the research, he said, was "understanding how the body tells the brain how much energy is stored" and discovering that the brain can be tricked.

Before starting the human research, the scientists identified the effect of the PPY 3-36 hormone on certain neurons in the brains of mice that were linked to appetite and weight control. Mr. Cowley said the animal studies and the human trials took only about a year combined, which Dr. Frank acknowledged was an extremely brief evaluation period.

Another author of the Nature study, Roger Cone, a neurobiologist at the Oregon Health & Science University in Portland, said the PPY 3-36 hormone "would not make a suitable weight-loss drug due to its potential effect on other important systems of the body."

He also said it was unclear how the body would react to elevated PPY 3-36 levels over time. Its use in the experiments in London was short-term.

Mr. Cowley said Mr. Cone's points are well-taken. "There's clearly the potential this [hormone] could act in many places" in the human body, he said.

Mr. Cowley said researchers were encouraged that no adults in the study suffered any cardiovascular effects from the injections of the hormone. "We watched heart rate and blood flow. All were normal," he added.

Dr. Frank says he does not believe any one drug or treatment would solve obesity, "given that there are so many kinds of obesity."

"No one thing controls it all. There's a lot of redundance," he said, adding that many laboratories are trying to find remedies for the "disease of obesity."

Obesity, defined as weighing 30 percent more than what is considered healthy, is described as an "epidemic" in the United States. In a speech at the National Press Club in late April, Tommy G. Thompson, secretary of the Department of Health and Human Services, said, "Sixty-one percent of American adults are overweight or obese."

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