Bears’ circadian rhythm superpower may hold key to human health

A genetic study confirms what has long been thought by observational studies, showing that grizzly bears’ biological clocks tick regularly, even when the animal is in deep hibernation. What’s more, their circadian rhythms are similar to ours, except these bears (Ursus) They can hibernate in the dark for four to seven months with few ill effects other than weight loss of up to 30%.

Scientists at Washington State University (WSU) believe the impressive physiology of these “extreme shift workers” may provide clues to how humans can better cope with circadian rhythm disruptions. Circadian rhythm misalignment is more common among shift workers and has been linked to heart disease, immunocompromise, metabolic diseases such as diabetes and obesity, stroke, cancer and premature death.

Researchers have found that the energy production of hibernating bears fluctuates from day to day, even if they haven’t eaten in months. During hibernation, their energy peaks are suppressed and occur later than when the animals are active, but they still clearly indicate that circadian rhythms are maintained rather than suspended.

“This underscores the importance of circadian rhythms themselves, which give organisms the flexibility to survive, like hibernating bears,” said senior author Heiko Jansen, professor in the Department of Integrative Physiology and Neuroscience at Washington State University. It can still function under extreme conditions.”

The research team believes that understanding how bears are able to gain large amounts of weight and then go months without food and little activity without adverse health effects could open the door to treatments for humans. The bears may lose up to 100 pounds (45 kilograms), but they lose very little muscle, experience no bone deterioration, and do not develop metabolic disease.

In this study, the researchers looked at the expression of circadian clocks in animals at the cellular level. Cell samples were collected and cultured from six bears during their active and hibernating periods. They compared cells taken from hibernating animals, which typically have a lower body temperature of about 34 °C (93.2 °F), with cells collected during the active season, which has a body temperature of about 37 °C (98.6 °F). °F).

Their findings confirmed circadian activity, with thousands of genes rhythmically expressed in hibernating animal cells. This suggests that adenosine triphosphate (ATP), the body’s cellular energy, is produced in a 24-hour cycle, albeit at lower peaks and troughs.

As mentioned earlier, energy output peaks also occur later in the day than when the animals are active, suggesting that bears alter their circadian rhythms during hibernation to reduce the cost of keeping their “battery” running. Because of this, they can continue to burn enough fuel to power their bodies without eating for months without developing harmful health problems.

“It’s like setting a thermostat,” Jensen said. “If you want to save some energy, you turn the thermostat down, which is essentially what bears do.”

While observing hibernating animals at the Washington State University Bear Center, researchers also noticed that the animals were more active during certain times of the day, even though light conditions remained the same. The increase in movement corresponds to a spike in ATP production by the hibernating animal’s cells.

“They’re exploiting the ability to suppress circadian rhythms, but they don’t stop the clock from running,” he added. “This is a truly novel way to fine-tune metabolic processes and energy expenditure in animals.”

The researchers believe that tapping into this ability may help humans cope with a schedule that requires them to “biologically” work at night and sleep during the day.

With an estimated 14% of the workforce enduring night work, there are growing concerns about the toll long hours have on human health, particularly chronic disease, accidents, poor quality of life and medical costs.

If scientists can figure out how to make our own body clocks smarter than those of the average bear, the potential to combat harmful health effects could be huge.

In another recent decade-long study, scientists found that bears also produce a unique anticoagulant protein during hibernation to protect them from the risks of prolonged immobility.

The research is published in the journal Journal of Comparative PhysiologyB.

Source: Washington State University

Leave a Comment

Your email address will not be published. Required fields are marked *

%d bloggers like this: