Most people first think of elephants when asked to name an animal that lives a particularly long time. Yet these gentle giants are not necessarily the animal that most interests scientists studying longevity. As it happens, researchers are keen to find out more about an animal that is no bigger than a mouse and looks rather like a hairless rat: the naked mole rat. With a lifespan of up to 30 years, it lives a very long time for an animal of its size – ten times longer than mice. Researchers led by Dr Martin Bens from the Leibniz Institute on Aging – Fritz Lipmann Institute (FLI) in Jena, working with scientists from the Leibniz Institute for Zoo and Wildlife Research (IZW), have now come one step closer to solving the mystery of why naked mole rats live to such a ripe old age.
A link between reproduction and long life
In a study, the researchers looked at how longevity is related to reproduction. What makes naked mole rats special is that one colony, which may contain dozens of animals, has its young provided by just one queen and one to three males. "The queen remains fertile until death", says Martin Bens. What is more, she lives longer than the other animals that are sexually inactive. Although these "workers" in the colony are capable of reproduction in principle, their sexual maturity is supressed by the presence of the dominant breeding pair – the "royal couple".
For the purposes of their study, the researchers removed male and female non-breeding workers from a colony and paired them with partners from a different colony. Because their sexual maturity was no longer suppressed by a "royal couple", they began to reproduce. The scientists then compared tissue samples from breeding and non-breeding animals. And discovered: "When naked mole rats reproduce, molecular signatures that indicate a longer lifespan can be found in their tissue", explains Martin Bens. In the sexually active naked mole rats for example, the mitochondria – the powerhouses of the cells – in the skin were less active. This lesser activity of the cellular powerhouses is associated with a longer life. The situation is different when it comes to guinea pigs, which are closely related to the naked mole rat: when they reproduce the number of molecular signatures that point to a longer lifetime is reduced.
Mole rats and humans: a useful lead for ageing research
Furthermore, in another study of these rodents, researchers from the FLI, the IZW and the Institute of Anaesthesiological Pathophysiology and Process Engineering at the Ulm University Medical Center (only in German) found that the ageing process in the animals shows similarities with ageing in humans. They discovered that when naked mole rats age, the same group of proteins in the liver is affected that is responsible for removing toxins from the human body. The scientists see this as a direct correlation between the ageing processes in mole rats and humans, which is a promising lead for ageing researchers to pursue.
The Leibniz Institute on Aging – Fritz Lipmann Institute (FLI)
In 2005 the FLI was the first national institute in Germany to focus its research activities entirely on the biomedical causes of ageing. More than 220 scientists from over 30 countries study the molecular principles of ageing and the development of diseases associated with ageing. The aim is to lay the foundation for new therapy approaches and thereby improve health in old age.www.leibniz-fli.de