Hormone Could Lead to a Fountain of Youth Research

Texas researchers have found a naturally occurring hormone that can extend the lifespan of mice by as much as 30%, a discovery that opens a new avenue of research into human longevity.

The hormone has a drawback, however: It decreases fertility and increases susceptibility to diabetes, the team reported Thursday in the online edition of the journal Science.

The hormone -- called klotho after one of the Greek fates who controlled the length of human life -- is produced in the brain and kidney in a variety of species but leaks into the bloodstream.

Pathologist Dr. Makoto Kuro-O and his colleagues at the University of Texas Southwestern Medical Center, who discovered the hormone, had previously reported that mice lacking the gene for klotho began showing signs of premature aging around 3 to 4 weeks of age and die after about two months. A normal mouse lifespan is two years.

The team genetically engineered mice to produce excess amounts of the hormone. They reported that the genetically engineered males lived 31% longer than normal males, and genetically engineered females lived 19% longer than their normal counterparts.

The team found that the hormone produced its effect by increasing the body’s resistance to insulin, a phenomenon that has been shown to correlate with extended lifespan.

Low-calorie diets that prolong life, for example, increase insulin resistance. Insulin resistance is also a symptom of diabetes, but the altered mice were not found to have unusually high levels of glucose in their blood, the primary symptom of the disease.

The hormone is also found in humans, and researchers are beginning to look to see if long-lived people have above-average levels in their blood.