Exceptional fertility of naked mole-rats could prolong that of humans

Naked mole rats appear to defy the biological rule of aging, making them somewhat enigmatic. Unlike humans and other mammals, which lose their fertility as they age, naked mole rats can reproduce throughout their very lengthy lifespans—the question of how has long baffled scientists for decades. 

Now, a new study published in Nature Communications on February 21 pinpoints unique processes that grant the rodents with what seems like eternal fertility. The discoveries could eventually point to new therapies for people.

What makes the fertility of naked mole rats so unusual?

"Naked mole rats are the weirdest mammals," said lead author Miguel Brieño-Enríquez in a press release. "They're the longest-lived rodent, they almost never get cancer, they don't feel pain like other mammals, they live in underground colonies, and only the queen can have babies."

"But to me, the most amazing thing is that they never stop having babies — they don't have a drop in fertility as they age. We want to understand how they do this," he added.

Brieño-Enríquez explained three possibilities for how naked mole rats do this. Contrary to most mammals and mice, (1) they are born with many egg cells, (2) not as many of these cells die, or (3) they continue to create more egg cells after birth.

Brieo-Enriquez and his team discovered proof of each of the three processes.

They found that compared to mice, naked mole-rat females contain unusually high quantities of egg cells and that the mortality rates of these cells were lower. For instance, a naked female mole rat at eight days old typically has 1.5 million egg cells, 95 times more than mice of the same age.

Most astonishingly, the scientists discovered that 3-month-old animals' egg precursor cells were actively dividing. These precursors were found in animals that were ten years old, indicating that oogenesis - the process that leads to their synthesis- may go on for the entirety of a naked mole rat's lifespan.

Can infertility be socially induced?

And that's not all. The researchers sought to understand better how a colony's sole dominant female (the "queen") prevents other females from reproducing to maintain her status.

They discovered that non-breeding subordinates had egg precursor cells in their ovaries. Still, the cells started dividing only after a transition to a queen.

"This is important because if we can figure out how they're able to do this, we might be able to develop new drug targets or techniques to help human health," said Brieño-Enríquez.

 "Even though humans are living longer, menopause still happens at the same age. We hope to use what we are learning from the naked mole-rat to protect ovary function later in life and prolong fertility."