A study by UT Southwestern Medical Center researchers finds that a starvation hormone markedly extends life span in mice without the need for calorie restriction.
"Restricting food intake has been shown to extend lifespan in several different kinds of animals. In our study, we found transgenic mice that produced more of the hormone fibroblast growth factor-21 (FGF21) got the benefits of dieting without having to limit their food intake. Male mice that overproduced the hormone had about a 30 percent increase in average life span and female mice had about a 40 percent increase in average life span," said senior author Dr. Steven Kliewer, professor of molecular biology and pharmacology.
The study published online in eLife - a new peer-reviewed, open access journal - defined average life span as the point at which half the members of a given test group remained alive. A study to determine differences in maximum life span is ongoing: While none of the untreated mice lived longer than about 3 years, some of the female mice that overproduced FGF21 were still alive at nearly 4 years, the researchers report.
FGF21 seems to provide its health benefits by increasing insulin sensitivity and blocking the growth hormone/insulin-like growth factor-1 signaling pathway. When too abundant, growth hormone can contribute to insulin resistance, cancer, and other diseases, the researchers said.
FGF21 is a hormone secreted by the liver during fasting that helps the body adapt to starvation. It is one of three growth factors that are considered atypical because they behave like hormones, which are substances created by one part of the body that have effects in other parts, the researchers said.
"Prolonged overproduction of the hormone FGF21 causes mice to live extraordinary long lives without requiring a decrease in food intake. It mimics the health benefits of dieting without having to diet," said co-author Dr. David Mangelsdorf, chairman of pharmacology and a Howard Hughes Medical Institute (HHMI) investigator at UT Southwestern.
"Aging and aging-related diseases represent an increasing burden on modern society. Drugs that slow the aging process would be very desirable. These findings raise the possibility of a hormone therapy to extend life span," said Dr. Mangelsdorf, who runs a research laboratory with Dr. Kliewer. They first identified FGF21-s starvation-fighting effects in a 2007 study.