Researchers attribute the change in the cell's structure and function in rats from fat storing to fat-burning to a massive increase in the action of mitochondria, the principal energy source of the cell. The increase in mitochondria, which also led to substantial weight loss in the rats, was found two weeks after researchers injected the leptin gene.
Findings from the study will appear in an upcoming issue of the Proceedings of the National Academy of Sciences and are currently available online.
"This is the first careful examination of the fat cells after leptin therapy," said Dr. Roger Unger, director of the Touchstone Center for Diabetes Research at UT Southwestern, a physician at the Dallas Veterans Affairs Medical Center and the study's senior author. "The structure of the cells changed from the normal appearance of a fat cell to a very novel cell that's really never been seen before. There's no precedent for a cell that appears like this.
"The ability to convert fat cells into fat-burning cells may suggest novel therapeutic strategies for obesity."
Dr. Unger and his collaborators began working on this research in 1996. During the initial phase of the study, Dr. Unger observed that the fat had disappeared in the fat cells, but at that time the researchers could only guess why.
"We predicted this in 1996, but until we showed the increase in mitochondria there was not any proof of what was happening, but there were many clues that the fat was being burned inside the cell," Dr. Unger said.