‘Eternal fertility’ of naked mole-rats may aid in human therapies, study shows

The “eternal fertility” of naked mole-rats seems to be the big takeaway in a recent study, co-authored by Cornell University College of Veterinary Medicine (CVM).

The findings, published Nature Communications, reveal the unique processes that allow a seemingly endless fertility in these rodents. Unlike humans and other mammals, which become less fertile with age, naked mole-rats are able to reproduce throughout their long lifespans.

While this in itself is a remarkable thought, the bigger potential the study aims to unlock is the ways in which the findings could impact the development of new human therapies.

“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,” says lead author, Miguel Brieño-Enríquez, MD, PhD, assistant professor at Magee-Womens Research Institute and the University of Pittsburgh School of Medicine’s Department of Obstetrics, Gynecology and Reproductive Sciences. “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.”

“Ovary health influences cancer risk, heart health, and even lifespan,” he adds. “Better understanding of the ovary could help us find ways to improve overall health.”

Most female mammals are born with a finite number of egg cells, which are produced in utero via a process called oogenesis. As this limited supply of egg cells depletes over time, fertility declines with age. In contrast, naked mole-rat queens can breed right through old age, suggesting the rodents have special processes to preserve their ovarian reserve and avoid waning fertility.

“There are three possibilities for how they do this: They are born with a lot of egg cells, not as many of these cells die, or they continue to create more egg cells after birth,” Dr. Brieño-Enríquez explains.

The research team found evidence for each of the three processes, and compared ovaries from naked mole-rats and mice across different stages of development.

The findings include: 

• Despite their similar sizes, mice live four years at most and start to show a drop in fertility by nine months, whereas naked mole-rats have a life expectancy of 30 years or more.
•  Naked mole-rat females have  large numbers of egg cells compared to mice, and death rates of these cells were lower than in mice. For example, at eight days old, naked mole-rat females had 1.5 million egg cells per ovary (i.e. about 95 times more than mice of the same age).
• Oogenesis happens postnatally in naked mole-rats. Egg precursor cells were actively dividing in three-month-old animals, and these precursors were found in 10-year-old animals, suggesting oogenesis could continue throughout their lives.

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