Anorexia linked to mystery molecule

16:55 27 March 03 NewScientist.com news service

Anorexic women have much higher levels of a mysterious molecule suspected to affect appetite, researchers have shown for the first time. The peptide, called CART, could be a candidate for new appetite-altering drugs, they say.

Levels of CART were 50 per cent higher in blood samples from anorexic women, compared with women without the eating disorder, says Sarah Stanley, an endocrinologist at Imperial College London. CART levels were also found to rise as the women's weight fell.

However, the function of CART in humans is not known. "And because we know so little, it is difficult to know if CART is the cause of the weight loss or the result," Stanley told New Scientist.

The team, based at Imperial College and the Eating Disorders Unit at London's Maudsley Hospital, will now proceed with experiments giving CART to humans to see if it has a real effect on appetite.

"Understanding the biology of anorexia nervosa is terribly important and any chink of light that might be shed on it through molecular research is certainly worth pursuing," says Stephen O'Rahilly, an expert in the molecular mechanisms of obesity at the Cambridge Institute for Medical Research, UK.

Up and down

CART is made in a variety of places in the human body including the brain, pituitary and adrenal glands. Studies in rats have linked the molecule to appetite. But CART both increases and reduces the appetite in rats, depending on which part of the brain it is injected into.

In the latest research, the team measured CART levels in the blood of anorexic women, anorexic women who were in the process of regaining weight, and recovered anorexic women who had maintained a normal body weight for a year. "We found a very, very strong correlation between plasma CART and body mass index," Stanley says.

Next, as well as giving CART to people, the team plans to examine CART levels in obese patients and those who have lost their appetite because they have a malignant disease. CART could also be a possible target for obesity drugs if it proves to reduce appetite, says Stanley.

"CART is definitely expressed in the appropriate parts of the hypothalamus to be involved," O'Rahilly told New Scientist. "But one should be cautious about leaping immediately to therapeutic applications." For example, it is difficult to know if measurements of CART in the blood reflect the situation in the brain, he says.

The findings were presented at the British Endocrine Societies annual meeting in Glasgow, UK.

Shaoni Bhattacharya