Scientists Move Closer To Drug For Treating Obesity

Scientists say they are a step closer to developing a drug for fat people after discovering the second half of the signaling system that tells the brain when the body has had enough to eat.

Scientists from Millennium Pharmaceuticals, in a report in Friday’s issue of the journal Cell, said the finding of a receptor on the surface of brain cells could lead to medication to alter how the “I’m full” signals are received.

The Cambridge-based Millennium researchers, collaborating with Hoffmann LaRoche, have been competing with other pharmaceutical labs and academic centers in an attempt to find the receptor gene ever since the discovery last year of the first major obesity gene, called OB, and the leptin protein it produces. That gene was isolated by Rockefeller University scientists.

Dr. Robert I. Tepper, senior author of the Cell paper, said that a drug to treat obesity is probably years away but that the new finding “will jump-start research at Millennium and elsewhere.”

The scientists say that while leptin is what sends the satiety message to the brain, it is not a lack of the hormone that causes obesity. On the contrary, most, if not all, obese humans have elevated levels of leptin.

The problem, the Millennium-La Roche team theorizes, may be that obese people are resistant to the message because of a deficiency in the leptin receptors or in the pathway leptin takes to the brain, Tepper said.

Scientists hope to bypass that resistance via drugs.

The receptor was found in two regions of the brain, Tepper said: the choroid plexus, which is known to transport substances from blood into the brain, and the hypothalamus, which regulates body temperature, weight and other functions.