Imma Perfetto
Cosmos science journalist
Humans can’t go long without water before feeling thirsty enough to rustle up a refreshing beverage. So how do hibernating animals suppress the need to seek out water for months at a time?
New research shows that for one animal, it’s all in the mind.
A species of squirrel, the thirteen-lined ground squirrel (Ictidomys tridecemlineatus), manages it by reducing the activity of a particular subset of neurons, blunting their sensitivity to thirst cues.
The study is in the journal Science .
The neurons are in brain structures known as circumventricular organs – connection points between the brain, blood circulation, and cerebrospinal fluid.
The squirrel – also known as the striped gopher – is found widely across the grasslands and prairies of North America. The species eats and drinks freely in the warmer months but avoids food and water while hibernating, which can last from 6 to 8 months.
During this time, the squirrel cycles between 2 physiological states: torpor and interbout arousal.
A thirteen-lined ground squirrel in torpor is inactive, with a suppressed metabolism and a body temperature of 2°C to 4°C, for a period of 2 to 3 weeks. Then, in a spontaneous 24-to-48-hour period of interbout arousal in which it moves around its burrow, its body temperature climbs to 37°C.
“We propose that squirrels use a 2-pronged strategy to optimise water conservation while minimising thirst,” the authors write in their paper.
In a previous study, the team showed that antidiuretic hormone-releasing neurons become activated at temperatures below 10°C.
Antidiuretics reduce urination, so this promotes water retention during the transition from torpor to interbout arousal
“In this work, we show that, when the transition to interbout arousal is complete, squirrels remain insensitive to physiological cues for thirst.”
