BRAIN'S APPETITE STIMULANT MAY BE KEY TO WEIGHT GAIN.

Byline: Theresa Tamkins Medical Tribune News Service

In yet another discovery that may help scientists unravel the mystery of appetite, eating and obesity, diabetes researchers have found a brain chemical that appears to regulate feeding and play a role in weight gain - this time by stimulating appetite.

A team from the Joslin Diabetes Center and Brigham and Women's Hospital in Boston reported that the compound, called melanin-concentrating hormone (MCH), is found in higher levels in the brains of obese mice than in lean mice.

When MCH was injected into normal mice, the animals consumed about twice as many calories as usual, said lead study author Dr. Eleftheria Maratos-Flier.

Last year, the biggest news in obesity research was the isolation of a natural hormone - called leptin - that suppresses appetite by interacting with receptors in the brain.

While the function of MCH is unknown, it is produced in the hypothalamus, the area of the brain that is thought to be the control center for weight regulation, and therefore must be viewed as a "potentially important" regulator of weight gain, Maratos-Flier noted in the report, published in the journal Nature.

"In theory, if this peptide turned out to have a powerful effect on food intake in other studies, blocking the effect with drugs may reduce food intake," said Dr. Rudolph Leibel, head of the human behavior and metabolism laboratory at the Rockefeller University in New York. "Or it may be used to increase food intake in people who are anorexic."

While last year's discovery of leptin at first was thought to be a "magic bullet" that could combat obesity, "what we are now seeing is the discovery of a whole series of additional proteins or genes that influence food intake and metabolism in very complex ways," he said.