It may seem counterintuitive, but could cutting back on calories help us preserve the body’s capabilities as we age?

According to new research from the Wisconsin National Primate Research Center (WiNPRC) at the University of Wisconsin (UW) School of Medicine and Public Health, monkeys on calorie-restricted diets age better than monkeys on a normal diet.

This is the latest in a series of papers from the Aging and Calorie Restriction Study based at WiNPRC. The series first garnered attention 10 years ago, when the improved survival and health benefits of calorie restriction were initially reported.

In the latest study, there were two groups of aged rhesus monkeys—one on a normal diet and another on a fully nutritionally complete diet with 30 percent fewer calories.

The scientists found that muscle mass was up to 20 percent better preserved in the calorie-restricted monkeys, and muscle quality also improved. These benefits were linked to better muscle function, more efficient movement and better diabetes risk profiles like blood glucose levels and insulin sensitivity.

“It’s all about metabolism,” said Associate Scientist Timothy Rhoads, PhD. “Not just in the muscle tissues themselves, but more broadly at the systemic level, too”.

Associate Professor of Medicine Rozalyn Anderson echoed his sentiments.

“Calorie restriction (CR) preserves muscle quality and physical function in monkeys, and our work connects this specifically to metabolism—how energy is derived, stored and used,” she said.

Researchers at the NPRCs across the country are helping to demystify the aging process. For additional reading, check out this recent study from the California National Primate Research Center (CNPRC), which examined the changing social habits of aging primates.

In general, as humans, healthy aging impacts our cognitive and affective functions. Our cognitive capacity declines while our emotional lives become more positive and social relationships take a more central role.

The reasons for this are unknown, though scientists suspect it may be because humans have awareness of a limited lifetime. This could possibly lead to a greater interest in maintaining social relationships at the expense of the non-social world in the face of waning cognitive and physical resources.

However, a recent study conducted by researchers at California National Primate Research Center (CNPRC) found humans may be unique in this regard.

The scientists tested whether old rhesus macaques lost interest in non-social stimuli, collecting data from males and females between 4 and 30 years old. Each macaque was tested with a food puzzle outfitted with an activity monitor to evaluate their inclination to manipulate the puzzle in order to gain a food reward. The team found no indication older macaques were less interested in the puzzle than younger ones, nor were they less able to solve it.

These findings suggest there are no significant age-related changes in environmental exploration — at least in rhesus macaques — and indicate there is more research to be conducted to understand such social phenomena across species.

We can’t stop aging—but can we slow down its consequences?

Scientists at the Southwest National Primate Research Center (SNPRC) on the Texas Biomedical Research Institute campus are working to find an answer using an animal model that continues to prove effective in this area.

Associate Professor Corinna Ross, PhD, and Professor Suzette Tardif, PhD, along with a team of researchers, conducted a study on adult marmosets (ages 2-17) that had been transferred to SNPRC from the New England Primate Center in 2015. Marmosets, in general, are recognized as an ideal nonhuman primate model of aging because they have relatively short lifespans and share age-related diseases similar to those of people.

Scientists took blood samples from the animals before and after the move, then re-evaluated them two years later. The team found that low levels of tryptophan metabolism were found to be associated with an increased risk of death.

Tryptophan is an amino acid that is linked to the production of serotonin, the chemical in the brain that contributes to feelings of happiness. Scientists aren’t yet sure whether serotonin influences aging, but there is a link between levels of tryptophan and health, Ross indicated.

The study also found that the metabolism of two other amino acids, betaine and methionine, were associated with aging regardless of environmental factors like stress. The results of the study suggest that the levels of metabolism of these three amino acids could be potential biomarkers for aging and related health issues.

This is “one of the first studies to discover metabo-lites (small molecules) [the levels of which] predict future mortality over a several year time span,” the authors concluded.

Following this study, marmosets may help scientists understand the subtleties of physiological aging and find ways to fight its negative health effects.

Curious about what other factors affect aging? NPRC research indicates the amount of calories you consume could have an impact as well.

Over the past 150 years, the average onset of puberty has been steadily declining. A century and a half ago, girls reached reproductive competence around 17.5 years of age—but now, the average age is 12.5 years. Early-onset puberty can lead girls to experience health problems later, including increased incidence of ovarian, uterine and breast cancers, as well as being at a higher risk for cardiovascular and metabolic diseases.

Researchers at the Oregon National Primate Research Center (ONPRC) at Oregon Health & Science University (OHSU) and the Brigham & Women’s Hospital and Harvard Medical School, wondered what was causing this increase in early bloomers. Their research led to the discovery of a new gene (MKRN3) that serves as a “neurobiological brake”, that when mutated advances pubertal development. Children with mutations in the MKRN3 gene show signs of pubertal development as early as 5 years of age. Without this biological pause button, developing kids would be more susceptible to cancer, cardiovascular disease, and metabolic disorders.

“Developing our knowledge of how genes regulate the initiation of puberty will allow us understand why girls are initiating puberty at much earlier ages,” said Dr. Alejandro Lomniczi, lead researcher on the study and assistant professor for the Division of Neuroscience at the ONPRC.

Focusing on the hypothalamus, the ventral part of the brain that controls reproductive development, Lomniczi and colleagues demonstrated that in monkeys and rodents, the MKRN3 gene is highly expressed during infancy and gets shut down right before puberty. Using genetic and biochemical approaches they demonstrated that MKRN3 is a strong repressor of KISS1 and TAC3 gene expression, two strong activators of pubertal development.

With these discoveries guiding their work, researchers are starting to construct the genetic architecture that regulates reproductive development in the brain and one step closer of breaking the “puberty” code.

Updated: June 2020

We’ve all heard the phrase “Mr. Mom” as a descriptor for involved fathers, but men may be more like their female counterparts when it comes to nurturing than we expect.

Most animals are risk-averse and tend to avoid danger, but parents can be a different story. Certain species of mammals will even risk their own lives to save their offspring.

This extreme bond between parent and child has its roots in a biological phenomenon known as “bonding.” When children are born, their mothers experience a rush of hormones designed to facilitate the bonding experience, including oxytocin, estrogen, progesterone and others.

Perhaps the most interesting hormone released during this process is prolactin, which stimulates lactation in new mothers to feed their offspring. It is intriguing not only because of its physical effect on mothers, but because it also appears in (and influences) their mates as well.

Researchers at the Wisconsin National Primate Research Center (WiNPRC) at the University of Wisconsin (UW) have discovered male tamarins and marmosets—which live in family units like those of humans—display certain physical characteristics when their respective mates become pregnant.

“The father is critical to the survival of the offspring,” Toni Ziegler, distinguished scientist at the WiNPRC, said of the animals during an interview on a recent BBC Earth podcast.  “And what we know about them from our studies, is the father is picking up on cues from the mother that she’s pregnant. And the father actually starts gaining weight.”

Ziegler noted this is consistent with human males, who frequently report gaining “sympathy weight” when their partners become pregnant.

This discovery could potentially lead to a better understanding of the bonding process and what can be done to nurture the infant-parent relationship from birth into early childhood.

Want to live longer? Eat less.  

That was the finding of a previous study by researchers at the Wisconsin National Primate Research Center (WiNPRC). And now, those same researchers may have discovered why.

“We knew that restricting calories helps monkeys to live longer, healthier lives, but we did not understand the basis for this extraordinary finding,” said Rozalyn Anderson, a professor and medicine and one of the study’s authors. Anderson worked closely with WiNPRC’s Dr. Ricki Colman, whose colony of rhesus monkeys was studied. “We are now at the beginning of a very exciting journey to discover how calorie restriction works on the molecular level.” Colman is a WiNPRC senior scientist and assistant professor at the University of Wisconsin-Madison.

Two groups of rhesus monkeys were studied for two years – one fed a normal diet while the other ate a diet with 30 percent fewer calories. The research team focused on the liver, because that is where nutrients are processed, and because it plays a key role in metabolic health. Through their research, the team catalogued more than 20,000 molecules in the rhesus liver and analyzed the data.

What the researchers found is that the lower calorie diet changed the way the liver was working, including how it metabolized proteins, carbohydrates, and lipids. Most surprising? The fact that calorie restriction was changing the metabolism on a genetic level using RNA processing.

“Although for some it will not be a surprise that metabolism is important to how calorie restriction works, we are talking about a dietary intervention after all,” said Anderson. “What is more interesting is the recent work showing profound metabolic effects in a whole host of age-associated diseases that are otherwise unrelated. We think that the metabolic response to calorie restriction is at the very heart of its ability to delay aging and the onset of age-related disease.”

While the implications of this discovery are still forthcoming, it’s certainly significant. In the meantime, keep on living, breathing, and eating – just not too much eating.

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Photo credit: Kathy West for the California National Primate Research Center

The controversy is over. Consuming fewer calories leads to a longer, healthier life, according to a joint report from the Wisconsin National Primate Research Center and the National Institute of Aging (NIA) on the diets of rhesus monkeys.

This report is the third in a series researching the effect of caloric intake on aging. In 2009, the UW–Madison team, led by primate center scientist Dr. Ricki Colman, reported that rhesus monkeys that ate less had fewer instances of cancer, cardiovascular disease, and insulin resistance. However, a 2012 study from the NIA showed no significant correlation between diet and health. With both teams hungry for an answer, they worked together to reach a more satisfying conclusion.

“These conflicting outcomes had cast a shadow of doubt on the translatability of the calorie restriction paradigm to understand aging and what creates age-related disease vulnerability,” said Rozalyn Anderson, an associate professor of medicine at UW–Madison collaborating with Dr. Colman and others on the study.

After comparing the two independent reports, the research team drew four key conclusions.

• Eating less is more beneficial for adult and older primates than for younger or juvenile animals.
• The number of calories reduced matters. The test group at UW–Madison ate less than the group at NIA and was less at risk for major health issues.
• Less processed food leads to fewer health issues. The NIA primates ate naturally sourced foods compared to the high-fat, sugar-rich diet of those at UW – Madison.
• Comparatively, females are less affected by a fatty diet.

While the two original studies considered caloric intake, they didn’t factor in the effect of age, diet, and sex. It’s those other ingredients, when evaluated alongside calorie count, that make up the complete recipe for healthy living. Energized by this discovery, researchers continue to explore the interaction between calorie count and quality of life.

Reviewed August 2019

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Photo credit: Yerkes National Primate Research Center

Are vaccines tied to an increased risk of autism? That’s the question researchers at the Washington National Primate Research Center (WaNPRC) are working to answer. While scientific research continues, the results of a recent study shows no obvious connection between following a vaccination schedule and brain defects.

The study focused on vaccines containing thimerosal, a chemical designed to protect the vaccine from bacterial contamination. This mercury-based compound, after decades of use, has largely been phased out at the recommendation of the Food and Drug Administration because of fears about an overexposure to mercury. However, flu and meningitis vaccines continue to use thimerosal.

“It is of great importance to determine whether childhood vaccines that contain this preservative play a significant role in altering brain development, such as autism,” said lead investigator Dr. Laura Hewitson of The Johnson Center for Child Health and Development and affiliate investigator with the WaNPRC.

Using a nonhuman primate model, the study showed no negative side effects such as rocking, self-clasping, or other repetitive behaviors after exposure to thimerosal-containing vaccines. In addition, research didn’t identify any noticeable neurochemical distinctions between vaccinated and unvaccinated test models.

This discovery is good news for advocates of childhood vaccinations, and by connection, for millions of kids  who receive vaccines each year. However, until there is a definite answer, the National Primate Research Centers will continue this research.

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Photo credit: Kathy West for the California National Primate Research Center