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

A communal dormouse successful a authorities of torpor

Simon Phillpotts/Alamy

Zapping portion of nan encephalon pinch focused ultrasound tin put mice successful a hibernation-like authorities called torpor for astatine slightest 24 hours. The aforesaid attack tin besides induce nan authorities successful rats, which, dissimilar mice, don’t people participate torpor.

“That has immense implications,” says Hong Chen astatine Washington University successful St. Louis. “The reasoning is that, if we show that successful animals that don’t usually participate nan torpor authorities we tin still induce a akin phenomenon, possibly we tin standard up nan exertion to larger animals.”

If this tin beryllium done successful people, too, it could person aesculapian uses among different things. For instance, inducing torpor successful group who person had strokes could bargain them clip and thief limit nan damage, says Chen.

Many warm-blooded animals little their assemblage somesthesia and slow down their metabolism to prevention energy, entering torpor. Some bats and birds go into torpor astatine night. Others, specified arsenic mice, participate it only erstwhile nutrient runs low. Hibernation involves extended periods of torpor interrupted by occasional returns to normal assemblage temperature.

In 2020, 2 teams independently discovered that stimulating portion of nan hypothalamus successful nan brains of mice tin induce torpor. However, they utilized analyzable methods, including familial engineering, to activate this “brain switch”.

Chen wondered if ultrasound could beryllium utilized instead. Her squad has been processing a method called focused ultrasound for treating encephalon diseases.

Chen’s squad recovered that a 10-second beat of ultrasound focused connected nan encephalon move area successful mice led to their assemblage somesthesia falling by astir 3°C (5.4°F). The mice recovered wholly aft 2 hours, but by delivering repeated pulses whenever their assemblage somesthesia started to rise, it was imaginable to support nan animals successful this authorities for 24 hours pinch nary motion of sick effects.

It mightiness beryllium imaginable to support this authorities for overmuch longer, says Chen, but her squad hasn’t yet tried to do this.

While nan method besides useful successful rats, their assemblage somesthesia only fell by astir 1.3°C (2.3°F).

“Although modest, this is important because rats are non-hibernators and, successful this, person to humans,” says Matteo Cerri astatine nan University of Bologna successful Italy, whose squad has induced torpor successful rats and pigs by chemically inhibiting a portion of nan brainstem.

Lowering assemblage somesthesia pinch ultrasound could beryllium useful for aesculapian purposes, but interplanetary recreation whitethorn require much robust ways to suppress metabolism, says Cerri.

Exactly really nan focused ultrasound induces torpor isn’t clear, says Takeshi Sakurai astatine nan University of Tsukuba successful Japan, whose squad was 1 of nan 2 that discovered nan hypothalamus switch.

It mightiness beryllium triggering this encephalon switch, says Sakurai. “However, location are besides different groups of neurons successful nan adjacent region that play a domiciled successful thermoregulation, making it much apt that they are besides involved.”

Chen thinks that a operation of nan section heating and beingness activity induced by nan focused ultrasound opens ion channels connected neurons, activating them. But this remains to beryllium established.

Any imaginable quality uses are still acold off, she says. “Safety is simply a large concern.” Focused ultrasound that is excessively aggravated aliases that is maintained for excessively agelong tin harm nan brain, and her squad had to do a batch of experiments to activity retired a safe dose successful a mouse.

But it is wholly feasible to create a helmet that could present focused ultrasound pulses to nan balanced portion of nan quality brain, she says.

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