The typical naked mole rat lives 25 to 30 years, during which it shows little decline in activity, bone health, reproductive capacity and cognitive ability. What is the secret to this East African rodent's long, healthy life? Scientists from the United States and Israel found a clue. From infancy to old age, naked mole rats are blessed with large amounts of a protein essential for normal brain function.

"Naked mole rats have the highest level of a growth factor called NRG-1 in the cerebellum（小脑） . Its levels are sustained throughout their life, from development through adulthood," said Yael Edrey, doctoral student at The University of Texas Health Science Center San Antonio's Barshop Institute for Longevity and Aging Studies.

Comparison across 7 species

The Barshop Institute has the largest colony of naked mole rats in the U.S. -- 2,000 rodents scampering around a network of tubes and cages in humid conditions that mimic their natural underground habitat. Edrey is the lead author of research that compared lifelong NRG-1 levels across seven species of rodents, from mice and guinea pigs（豚鼠） to blind mole rats and Damaraland mole rats.

NRG-1 levels were monitored in naked mole rats at different ages ranging from 1 day to 26 years. The other six rodent species have maximum life spans of three to 19 years.

The cerebellum coordinates movements and maintains bodily equilibrium（均衡，平静） . The research team hypothesized that long-lived species would maintain higher levels of NRG-1 in this region of the brain, with simultaneous healthy activity levels.

Among each of the species, the longest-lived members exhibited the highest lifelong levels of NRG-1. The naked mole rat had the most robust and enduring supply. "In both mice and in humans, NRG-1 levels go down with age," Edrey said.