Novel Weight Management Role for Existing Drug

Rapamycin is a pharmaceutical used to coat coronary stents and prevent transplant rejection.  A number of recent published studies suggest its potential to modulate the aging immune system, promote nerve growth factor, and change the liver transcriptome.  Christy S. Carter, from the University of Florida (Florida, USA), and colleagues observe that rapamycin reduced food consumption and body weight, in a laboratory animal model. Using 25-month-old rats (about equivalent to 65-year-old people), the team found that body weight dropped by approximately 13% after treatment with rapamycin. The drug targets how the body makes leptin, a hormone produced by fat cells that affects hunger and metabolism. The researchers hypothesize that the reduction in eating is due to normalizing the typical age-related spike in leptin. As well, there was a dramatic body metamorphosis: rapamycin selectively targeted the fat, allowing the animals to retain lean mass. It worked so well that the older rats ultimately developed a lean-to-fat ratio similar to that of their younger counterparts, researchers found.  In a second study by the same co-lead investigator, small, intermittent amounts of rapamycin produced the desired slimming effect in both young and old rats. The authors of the second study submit that: “Our data suggest that the dosing schedule of rapamycin acts on peripheral targets to inhibit mTORC1 signaling, preferentially reducing adiposity and sparing lean mass in an aged model of obesity resulting in favorable outcomes on blood triglycerides, increasing lean/fat ratio, and normalizing elevated serum leptin with age.”