By Merritt McKinney
NEW YORK, Sep 20 (Reuters Health) -- A hormone that helps regulate weight in mice appears to have a similar effect in people, according to a report in The New England Journal of Medicine. The research suggests that the hormone, leptin, may have a role in treating obesity, although that remains to be proven, researchers caution.
Two years ago, scientists reported on two severely obese cousins who lacked leptin due to a genetic mutation. In the new report, Dr. Stephen O'Rahilly, of Addenbrooke's Hospital in Cambridge, UK, and colleagues report that treatment with leptin helped one of the cousins, a 9-year-old girl, to control her appetite and lose weight.
Before receiving daily injections of leptin, the girl was hungry around the clock and constantly demanded food. Although she was tall for her age, the child was grossly obese, weighing about 200 pounds.
Within a week of starting the treatment, however, the girl's eating behavior began to change, O'Rahilly and colleagues report. Not only did she stop demanding food between meals, but she began eating the same amount of food as her siblings, who were not overweight. And about 2 weeks after starting the therapy, the girl began to lose weight. After a year of leptin injections, she had lost a little more than 36 pounds, according to O'Rahilly's team.
The treatment did not appear to cause any side effects in the girl, the researchers report.
Based on the results, the investigators conclude that leptin plays a role in regulating appetite and weight control in people.
However, O'Rahilly told Reuters Health that it would be premature to assume that leptin therapy may help other obese people keep their weight under control.
"Most obese people have normal or high levels of leptin in their blood," O'Rahilly told Reuters Health. "Whether giving more leptin to these people would have any beneficial effects on their weight is still an open question," he noted.
In an editorial accompanying the study, Drs. Michael Rosenbaum and Rudolph L. Leibel, of the Columbia University College of Physicians and Surgeons in New York, note that in most cases obesity is caused by a combination of a natural tendency to store extra calories as fat, overeating, and not getting enough exercise.
Whether or not leptin proves to be a safe and effective treatment for obesity remains to be seen. A better understanding of how leptin regulates appetite and weight control may lead eventually to other medications to treat obesity, the editorialists conclude.
