New York: In a big breaking discovery, the researchers may have found the beginnings of a path toward increasing human lifespan.
The study, published in the Journal of Gerontology: Biological Sciences, shows the drug mifepristone can extend the lives of two very different species used in laboratory studies, suggesting the findings may apply to other species, including human beings.
Mifepristone, also known as RU-486, is used by clinicians to end early pregnancies as well as to treat cancer and Cushing disease.
Studying one of the most common laboratory models used in genetic research - the fruit fly Drosophila - the researchers found that the drug mifepristone extends the lives of female flies that have mated.
"Our data show that in Drosophila, mifepristone either directly or indirectly counteracts juvenile hormone signalling, but the exact target of mifepristone remains elusive," said study researchers from the University of Southern California in the US.
According to the researchers, during mating, female fruit flies receive a molecule called sex peptide from the male.
Previous research has shown that sex peptide causes inflammation and reduces the health and lifespan of female flies.
The research team found that feeding mifepristone to the fruit flies that have mated blocks the effects of sex peptide, reducing inflammation and keeping the female flies healthier, leading to longer lifespans than their counterparts who did not receive the drug.
The drug's effects in Drosophila appear similar to those seen in women who take it.
"In the fly, mifepristone decreases reproduction, alters innate immune response and increases life span," the study researcher John Tower explained.
"In the human, we know that mifepristone decreases reproduction and alters the innate immune response, so might it also increase life span?" he added.
Seeking a better understanding of how mifepristone works to increase lifespan, the research team looked at the genes, molecules and metabolic processes that changed when flies consumed the drug.
They found that a molecule called juvenile hormone plays a central role. Juvenile hormone regulates the development of fruit flies throughout their life, from egg to larvae to adult.
Sex peptide appears to escalate the effects of juvenile hormone, shifting the mated flies' metabolism from healthier processes to metabolic pathways that require more energy to maintain.
Further, the metabolic shift promotes harmful inflammation, and it appears to make the flies more sensitive to toxic molecules produced by bacteria in their microbiome.
Mifepristone changes all of that.
According to the researchers, when the mated flies ate the drug, their metabolism stuck with the healthier pathways, and they lived longer than their mated sisters who did not get mifepristone.
"Notably, these metabolic pathways are conserved in humans, and are associated with health and longevity," the study authors wrote.