Science

Obesity drug fails to trim

A potential obesity drug that targeted a hunger factor in the brain showed disappointing results in a clinical trial, a sign that major weight loss may need more than one approach, researchers say.

A potential obesity drug that targeted a hunger factor in the brain showed disappointing results in a clinical trial, a sign that major weight loss may need more than one approach, researchers say.

The drug, known as MK-0557, was developed by Merck & Co. to block brain receptors that respond to hunger signals.

But when researchers randomly assignedmore than 1,600 obese people to take the drug or a placebo, they found those taking it lost an average of 7.5 pounds during the 12-month study, compared with an average of four pounds in the placebo group— not clinically significant enough tomarket the drug.

"The current findings add to a growing sense that you will have to try a lot of different targets or get an even better understanding of the scientific underpinnings in order to unwire the food intake system with some combination of drugs," said study author Steven Heymsfield, executive director of clinical sciences at Merck.

The drug was well tolerated among the 832 people who completed the trial, the researchers report in the October issue of the journal Cell Metabolism.

Earlier studies on leptin, a hormone that regulates weight and appetite, also showed mixed results for weight loss.

Appetizers and addicts

A related hunger experiment appearing in the same issue of the journal concluded the idea of whetting the appetite by serving hors d'oeuvres before a meal may have a scientific basis.

The study on rats trained on a strict feeding regime for 10 days showed brain activity in a key hunger centre spiked with the first bites of food, and expectation of food turned on brain cells involved in triggering hunger.

"The drive to eat is massively stimulated by the start of eating," researcher Gareth Leng of the University of Edinburgh said in a release. "This shows the appetizing effect of food itself as hunger circuits are acutely switched on."

The rats' appetite was only whetted for a short time, as the brain's centre for registering satiety or fullness kicked in almost as soon as food hit the stomach, the researchers said.

A third appetite study appearing in this week's issue of the Proceedings of the National Academy of Sciences found the brain circuits involved when obese people overeat are the same as those in addicts craving a drug.

Lead researcher Gene-Jack Wang at the Brookhaven National Laboratory in New York and his team looked at brain impulses in seven overweight people who were all previously fitted with a gastric stimulator device that sends electronic signals to the brain, tricking it into thinking the stomach is full.

Brain scans showed more activity in the hippocampus, an area of the brain associated with emotional behaviour, learning and memory, when the device was on. The pattern of brain activity resembled that linked to cravings in cocaine addicts.

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