Leptin leapt into the headlines when it was identified in 1995 as a protein that triggers weight loss in mice. But the appetite-taming hormone lost some luster as the ultimate diet drug when scientists found last year that obese people already have high levels of leptin in their blood. This finding suggested that overweight people may become unable to respond to leptin, though little is known about leptin's interactions in the body.
Now investigators at Washington University School of Medicine in St. Louis have identified the first factor to significantly boost human leptin concentrations. And surprisingly, this substance also boosted leptin levels in some overweight individuals.
In the study conducted by endocrinologist Samuel Dagogo-Jack, M.D., assistant professor of medicine, and by John W. Newcomer, M.D., assistant professor of psychiatry and of psychology, oral administration of a steroid hormone for four days doubled the amount of circulating leptin in 52 patients. Levels of leptin, a product of fat cells, climbed even higher in obese subjects. The results were published in the October 1997 issue of the Journal of Clinical Endocrinology and Metabolism.
Dagogo-Jack says the findings suggest that overweight people still have leptin reserves. "Because their supplies are not exhausted," he notes, "future leptin therapy may require the use of high doses of leptin to make a dent in obese people's weight."
A similar approach works well in people with adult-onset, or type 2, diabetes, who are resistant to their own insulin. "If we treat these diabetics with insulin to increase their circulating insulin levels, their blood glucose concentrations come down, and their diabetes is controlled."
Heavier People Respond Better
The study, which was funded by grants from the National Institute of Mental
Health, the American Diabetes Association and the U.S. Public Health Service,
involved 20 healthy men and 32 healthy women ranging from 19 to
Contact: Barbra Rodriguez
Washington University in St. Louis