Monkey experiment reveals brain switch that could be useful for space travel: ScienceAlert

In order for humans to ever venture among the stars, we will have to solve big logistical problems.

Travel time is not the least of them. Space is so vast and human technology so limited that the time it would take to get to another star presents a significant hurdle.

The Voyager 1 probe, for example, would take 73,000 years to reach Proxima Centauri, the closest star to the Sun, at its current speed.

Voyager was launched over 40 years ago, and newer spacecraft can be expected to travel faster; even so, the journey would still take thousands of years with our current technology.

One potential solution would be Generation Ships, which would see multiple generations of space travelers live and die before reaching the final destination. Another would be artificial hibernation, if it could be successfully implemented.

This is what scientists from the Shenzhen Institute of Advanced Technology (SIAT) of the Chinese Academy of Sciences have started to study; not in humans, but in monkeys, by chemically triggering a state of hypothermia.

“Here, we show that activation of a subpopulation of preoptic area (POA) neurons by a chemogenetic strategy reliably induces hypothermia in anesthetized and freely moving macaques,” the researchers write in their article.

“Overall, our findings demonstrate the central regulation of body temperature in primates and pave the way for future application in clinical practice.”

Hibernation and its slightly less comatose state, torpor, are physiological states that allow animals to withstand adverse conditions, such as extreme cold and lack of oxygen.

Body temperature drops and metabolism slows, keeping the body in a rudimentary “maintenance mode” – the bare minimum to stay alive while preventing atrophy.

It can be found in several animals, including warm-blooded mammals, but very few primates. SIAT neuroscientists Wang Hong and Dai Ji wanted to see if they could artificially induce a state of hypometabolism, or even hibernation, in primates by chemically manipulating neurons in the hypothalamus responsible for sleep and thermoregulation processes – preoptic neurons.

The research was carried out on three young male crab-eating monkeys (macaca fascicularis). In anesthetized and unanesthetized states, researchers applied drugs designed to activate specific altered receptors in the brain known as designer receptors exclusively activated by designer drugs, or DREADDs.

Then the scientists studied the results using functional magnetic resonance imaging, behavioral changes, and physiological and biochemical changes.

An illustration showing the role preoptic neurons play in hypothermia. (SIAT)

“To study the brain network following preoptic area (POA) activation, we performed fMRI scans and identified several regions involved in thermoregulation and interoception,” Dai explains.

“This is the first fMRI study to investigate brain-wide functional connections revealed by chemogenetic activation.”

Researchers found that a synthetic drug called Clozapine N-oxide (CNO) reliably induced hypothermia in anesthetized and awake states in macaques.

However, in anesthetized monkeys, CNO-induced hypothermia caused a drop in core body temperature, preventing external heating. The researchers say this demonstrates the critical role POA neurons play in primate thermoregulation.

The researchers recorded behavioral changes in the awake monkeys and compared them to those of mice suffering from induced hypothermia. Typically, mice decrease their activity and lower their heart rate in an attempt to conserve heat.

The monkeys, on the other hand, showed an increase in heart rate and activity level and, in addition, started to shiver. This suggests that thermoregulation in primates is more complex than in mice; hibernation in humans (if it can be done at all) will have to take this into account.

“This work provides the first successful demonstration of hypothermia in a primate based on targeted neural manipulation,” Wang said.

“With the growing passion for human spaceflight, this hypothermic monkey model is an important step on the long road to artificial hibernation.”

The research has been published in innovation.

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