Scientists interested in studying successful aging and longevity have found a particularly good example: the naked mole rat. When kept in laboratories, these burrowing rodents have been reported to live nearly 30 years, making them the longest-lived rodent known.

A study by researchers at the Barshop Institute for Longevity and Aging Studies at the University of Texas in San Antonio reveals mechanisms in the cells of naked mole rats that could explain their impressive longevity. Compared with mice (which typically live three to four years), naked mole rats have better ways of maintaining the health of proteins in their cells, according to the study, published this week in Proceedings of the National Academy of Sciences. Coauthor Rochelle Buffenstein, a physiologist at the Barshop Institute, says that uncovering tricks that slow-aging animals use to extend their life span could point to strategies for alleviating diseases of aging in humans.

Buffenstein has been studying the naked mole rat for decades but recently became interested in the animals as "a model to study successful aging." Although their pale, wrinkled skin and poor eyesight might not evoke the picture of health, mole rats not only live a long time, but they also seem to experience healthier aging than most animals. They have little incidence of cancer and few signs of bodily degeneration; females can breed up until their death.

One long-standing theory of aging is that it results from the slow degeneration of cells through contact with oxygen, called oxidative stress. But paradoxically, naked mole rats have higher levels of oxidative damage in their cells than do mice, even from a young age. To understand why these animals seem to be resistant to the effects of oxidation, Buffenstein and her colleagues at the Barshop Institute looked at the rodents' proteins, one of the key targets of oxidative damage.

Buffenstein worked with biochemist Asish Chaudhuri to compare the structure of proteins in the liver tissue of old and young naked mole rats to those in mice using high-throughput methods recently developed in Chaudhuri's lab. The analyses showed that proteins in mole-rat cells are more resistant to unfolding, making them more stable than those of mice.

The researchers also found evidence that the cells of mole rats have more efficient mechanisms for getting rid of improperly folded or oxidized proteins. Buffenstein says the results suggest that naked mole rats can withstand oxidative damage better by keeping their proteins stable and quickly removing unfolded proteins before they can accumulate.