Known as induced torpor - hibernation is an example - it is a condition found in many species as a means to protect them against times of food scarcity and low environmental temperatures. The researchers believe that replicating hibernation may therefore protect astronauts against the harsh conditions of space flight, which include challenges such as radiation exposure, bone and muscle wastage, advanced ageing and vascular problems.
“NASA plans to return to the Moon and onward to Mars in the coming years. Recent technological advancements have made space travel more accessible, however, long-term space travel is incredibly detrimental to human health,” said Professor Gary Hardiman, researcher from the Institute for Global Food Security (IGFS) at Queen’s, in a press release.
“We set out to determine if induced torpor is a viable countermeasure to the harmful effects of spaceflight. If humans could replicate a similar model of hibernation we have observed in the zebrafish, it could increase our chances of making humans a spacefaring species. For example, it would lead to reduced brain function which would cut down on psychological stress. The change to their metabolism would stop them requiring food, oxygen or water and there is a possibility it would protect their muscles from wasting due to the effects caused by radiation and microgravity,” he added.
To conduct their study, the researchers exposed zebrafish to a similar level of radiation to what would be experienced on a six-month journey to Mars. The researchers found that this caused signatures of oxidative stress, stress hormone signalling and halting of the cell cycle within the zebrafish.
The researchers then induced torpor in a second group of zebrafish which were then exposed to the same dose of radiation and analysed their gene expression patterns to assess the protective effects during this induced state of physical or mental inactivity.
The results found that torpor lowered the metabolic rate within the zebrafish and created a radioprotective effect, protecting against the harmful effects of radiation.
Thomas Cahill, PhD student from IGFS, said: “Our results reveal that whilst in induced torpor, the zebrafish showed that a reduction in metabolism and oxygen concentration in cells promotes less oxidative stress and greater resistance to radiation.
"These insights into how a reduction in metabolic rate can offer protection from radiation exposure and could help humans achieve a similar kind of hibernation, counter measuring the damage they currently face during spaceflight.”
The research has been published, under the title Induced Torpor as a Countermeasure for Low Dose Radiation Exposure in a Zebrafish Model, in the journal MDPI Cells.