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Animals that defy the rules of aging — like naked mole rats — could help scientists unravel the secrets to longevity

Animals that defy the rules of aging — like naked mole rats — could help scientists unravel the secrets to longevity

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Neil Bromhall/Shutterstock
  • Some long-living animals seem to defy the rules of aging, so scientists are studying them.
  • Two animals of interest to researchers are the naked mole rat, which lives decades longer than its rodent relatives, and turtles, which can live up to 200 years.
  • Researchers have found noticeable differences in the ways these animals’ metabolisms and mitochondria function.

Being a freak of nature isn’t always a bad thing, especially if you defy the conventions of aging.

Naked mole rats and turtles are outliers when it comes to the rules of nature. The mole rat lives up to 31 years, decades longer than its other rodent relatives. Turtles are one of the longest-living creatures on Earth.

Comparing the biology of these animals to others that age poorly provides valuable insights to scientists about which biological pathways are most important for longevity. That information could ultimately help them find ways to increase human lifespans.

A cornucopia of factors are at play as a younger organism gets older: proteins get damaged, they build up and disrupt cell functions, mutations occur, and once-harmless cells turn into cancer. But the important question when it comes to aging is not how it happens, according to Richard Miller, director of the Glenn Center of Aging Research at the University of Michigan.

“The real question is what has been done across species or within a species to slow it,” Miller told Business Insider.

Long live the naked mole rat

A popular theory in the field of aging is that an organism puts most of its resources – such as nutrients, energy, time and effort – either into maintaining their body or reproducing, but not both. In people, for example, women’s average lifespan decreases if they have children. Scientists believe this happens because human reproduction can cause damage to cells and deplete resources in the body that would otherwise have been used for cellular repair.

But paradoxically, breeding seems to extend the life of the naked mole rat.

Scientists Martin Bens and Alessandro Ori at the The Leibniz Institute on Aging in Germany are working to understand this anomaly.

Each colony of mole rats designates a queen, the same way ants do, and only she breeds and bears young. There is also only one breeding male per colony. But non-breeders can transition to become a breeder, so Bens and Ori studied that transition process.

Their results suggested that the signal pathways involved in mole rats’ transition to breeding are also involved in their aging process.

In males, some of these overlapping pathways are related to their metabolism, the process of converting food to usable units of energy in the body. Scientists found that breeding male mole rats produced greater-than-normal amounts of energy in their testes cells, and lower-than-normal amounts in their skin cells. Diverting energy in this way could play a role in delaying the aging process.

Naked Mole Rats

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Brandon Vick, University of Rochester

Ori and Bens also observed differences in the composition of the mole rats’ mitochondria: the small organelles in cells that power metabolic processes. They observed that the naked mole rats had a reduced mitochondria respiration rate compared to guinea pigs, which meant that the mole rats were making less energy and using less fuel and oxygen.

The researchers also found that all the naked mole rats preferred to use lipids or fats as an energy source, rather than the carbohydrates or sugars that shorter-lived rodents mostly use.

Another factor that allows naked mole rats to live so long is their abnormally low body temperature. Lower basal body temperatures in animals are usually correlated with prolonged healthspan, and naked mole rats are mammals but aren’t warm-blooded, which makes them an anomaly in the rodent family.

Finally, Ori and Bens examined naked mole rats’ livers. Livers generally detoxify the body and eliminate chemicals that can damage cells and accelerate aging. In mole rats, these detox pathways were more active than the same systems in guinea pigs, suggesting that mole rats keep their cells healthy and undamaged from toxins more efficiently. That could also explain why they out-live their rodent cousins.

The tortoise and the human

Tortoises and turtles are masters of aging. Jonathan, a Seychelles giant tortoise, is the oldest known terrestrial animal at 186 years of age, and is going strong.

“There are tortoises until recently that knew Darwin personally,” Kenneth Storey, a professor at Carleton University who studies turtles, told Business Insider.

These ancient beings are the most evolved and complex animal that can survive complete anoxia: a total absence of oxygen. Turtles can go well over a year without oxygen.

By comparison, naked mole rats can survive almost 20 minutes without oxygen, and oxygen-deprived humans only get about two minutes of brain activity and five minutes of heart activity before all systems shut down and organs become irreparably damaged.

To live without oxygen, Storey said, turtles drop their metabolism rate to next to nothing.

“What the turtles do is in a tissue-specific manner, shut down genes and sub-cellular organelles that use energy or that need maintenance,” he said.

A giant green turtle rests on a coral reef in the Celebes Sea, November 7, 2005.

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A giant green turtle rests on a coral reef in the Celebes Sea, November 7, 2005.
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Reuters

Turtles shut their energy production off by changing an enzyme called pyruvate dehydrogenase, which turns off their mitochondria.Starving the mitochondria then forces the turtle’s body to secrete a special protein that protects cells.

In the absence of oxygen, turtles can initiate an organized shutdown of 50,000 processes in their bodies.

“We know what happens to the pathways and we know what happens to the system, but we don’t know what ultimately controls it,” Storey said.

He added that under stressful, low-oxygen conditions, turtles’ bodies do one other thing exceptionally well: “They don’t panic.”

In these circumstances, turtles turn off most of their stress-response proteins so they can focus what little energy they have on reshaping their cells to operate differently in anoxic conditions. Those changes include preventing cells from digesting and turning over proteins, a process called autophagy that can make detritus and cause damage. Limiting the amount of matter created and destroyed in their bodies allows turtles to maintain a pristine internal balance.

By comparison, human cells that are deprived of oxygen turn on stress kinases: signaling proteins that help facilitate communication in the body in order to respond to a challenging situation. Over-activating stress kinases can use up a lot of energy, overload the system, and ultimately trigger cell death.

When juxtaposing humans and turtles, Storey thinks longevity depends on an energy trade-off.

“Think of these lower animals as living longer than us because their pilot light is lower. They’re not 37 degrees [Celsius], they’re not racing around,” he said. “They’re not burning the candle at both ends, they’re barely burning the candle at one end, and during anoxia they stop burning the candle. That’s how they can live so long. It’s a pace argument.”

All about energy

The idea that metabolism is one of the key factors in the aging process has been a cornerstone of many studies on aging. Hypothetically, if you turned down the energy production in your cells, you could live longer and get fewer wrinkles, Storey said. But you would probably not have enough energy to sustain a normal human life.

Humans’ complexities mean we require more energy and a constant supply of oxygen to power our cells. We also need to consume food frequently to fuel our bodily functions.

“What we’ve opted for is a high velocity lifestyle, which ties us in to oxygen all the time,” Storey said.

Rozalyn Anderson, an associate professor at the University of Wisconsin School of Medicine and Public Health, told Business Insider that it’s hard to ignore how big a role metabolism and energy balance play in aging. Anderson studies caloric restriction in monkeys, and said evidence is starting to show that age-related diseases show up with increased prevalence in people who have metabolic issues and obesity.

“I think it’s all about energy: energy use, energy storage, and the type of pathways that are being engaged to derive energy,” Anderson said.

Owning a dog can help your health

Owning a dog can help your health

As most of us know by now, this Chinese New Year marks the beginning of the Year of the Earth Dog in the Chinese zodiac.

In celebration of man’s best friend, we round up how your furry friend could give your health a boost in the coming year.

Reduced risk of allergies

Various studies have now found a link between owning a dog and a lower risk of allergies, especially in children.

Research presented in 2017 at the American College of Allergy, Asthma and Immunology (ACAAI) Annual Scientific Meeting detailed how children of mothers who had been in daily contact with a dog while pregnant had a lower risk of eczema by age two, and that pet dogs could also have a protective effect against asthma symptoms.

Swedish researchers also found, after looking at more than one million Swedish children, that those who grew up with dogs had a 15% lower risk of asthma.

Better sleep

A small American study found that despite a dog’s snoring, sleeping with your pooch could actually help you get a better night’s sleep.

After recruiting 40 adults and their pets for the study, researchers at the Mayo Clinic in the United States found that regardless of the size of the dog, sleeping with a furry friend in the room helped some people sleep better.

However, having a dog on the bed didn’t have the same effect, with the team finding that those who let their canines get too cozy, did it at the expense of a good night’s sleep.

“Most people assume having pets in the bedroom is a disruption.

“We found that many people actually find comfort and a sense of security from sleeping with their pets,” commented the study’s author Dr Lois Krahn.

Improved mental health

After looking at 17 research papers, a British review published just this week found that having a pet could have a positive effect on managing long-term mental health conditions.

Owning a dog, or other animal such as a cat, goldfish or hamster, was found to be beneficial by helping to distract owners from the stress of having a mental health problem and helping to alleviate feelings of loneliness.

Dogs also had the added benefit of helping owners increase their level of physical activity through walking, which in turn can also help improve mental health and encourage social interaction with other dog owners.

Pet dogs have also been found to help support children when they are stressed, while a 2015 American study found that children who have a dog at home also have a lower level of anxiety than those who do not.

More exercise

It can be hard to find the motivation to get moving sometimes, but most dog owners will tell you, you don’t have much choice if your dog is asking for walks.

Many recent studies have also found that those with a dog do indeed get more exercise, with a dog being especially beneficial for helping seniors to get out of the house and get moving.

A British study published in 2017 found that seniors who walk their dogs clock up around 30 minutes more physical activity a day than non-dog owners, even during the colder, wetter months, with an Australian study also finding that dog walkers achieved at least 30 minutes of physical activity on more days per week than non-dog walkers, helping them to meet the 150 minutes of physical activity per week currently recommended for good health. – AFP Relaxnews

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