Ultrasound can trigger a hibernation-like state in mice and rats

Ultrasound can trigger a hibernation-like state in mice and rats

A typical dormouse in a state of torpor

Simon Phillpotts/Alamy

Zapping a part of the mind with centered ultrasound can put mice in a hibernation-like state known as torpor for no less than 24 hours. The identical method also can induce the state in rats, which, not like mice, don’t naturally enter torpor.

“That has large implications,” says Hong Chen at Washington College in St. Louis, Missouri. “The pondering is that, if we present that in animals that don’t usually enter the torpor state we are able to nonetheless induce an identical phenomenon, perhaps we are able to scale up the know-how to bigger animals.”

If this may be executed in individuals, too, it may have medical makes use of amongst different issues. As an illustration, inducing torpor in individuals who have had strokes may purchase them time and assist restrict the harm, says Chen.

Many warm-blooded animals decrease their physique temperature and decelerate their metabolism to save lots of power, getting into torpor. Some bats and birds go into torpor at evening. Others, equivalent to mice, enter it solely when meals runs low. Hibernation includes prolonged durations of torpor interrupted by occasional returns to regular physique temperature.

In 2020, two groups independently found that stimulating a part of the hypothalamus within the brains of mice can induce torpor. Nevertheless, they used complicated strategies, together with genetic engineering, to activate this “mind swap”.

Chen questioned if ultrasound might be used as a substitute. Her staff has been growing a way known as centered ultrasound for treating mind illnesses.

Chen’s staff discovered {that a} 10-second pulse of ultrasound centered on the mind swap space in mice led to their physique temperature falling by round 3°C (5.4°F). The mice recovered utterly after 2 hours, however by delivering repeated pulses at any time when their physique temperature began to rise, it was doable to maintain the animals on this state for twenty-four hours with no signal of ailing results.

It may be doable to keep up this state for for much longer, says Chen, however her staff hasn’t but tried to do that.

Whereas the approach additionally works in rats, their physique temperature solely fell by round 1.3°C (2.3°F).

“Though modest, that is necessary as a result of rats are non-hibernators and, on this, nearer to people,” says Matteo Cerri on the College of Bologna in Italy, whose staff has induced torpor in rats and pigs by chemically inhibiting part of the brainstem.

Decreasing physique temperature with ultrasound might be helpful for medical functions, however interplanetary journey might require extra strong methods to suppress metabolism, says Cerri.

Precisely how the centered ultrasound induces torpor isn’t clear, says Takeshi Sakurai on the College of Tsukuba in Japan, whose staff was one of many two that found the hypothalamus swap.

It may be triggering this mind swap, says Sakurai. “Nevertheless, there are additionally different teams of neurons within the close by area that play a job in thermoregulation, making it extra possible that also they are concerned.”

Chen thinks {that a} mixture of the native heating and bodily motion induced by the centered ultrasound opens ion channels on neurons, activating them. However this stays to be established.

Any potential human makes use of are nonetheless far off, she says. “Security is an enormous concern.” Targeted ultrasound that’s too intense or that’s maintained for too lengthy can harm the mind, and her staff needed to do a number of experiments to work out a secure dose in a mouse.

However it’s solely possible to develop a helmet that would ship centered ultrasound pulses to the equal a part of the human mind, she says.


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