Studying the zebrafish could advance efforts to reach Mars, say researchers, by understanding how a form of hibernation, known as induced torpor (a state of reduced metabolic activity) may provide radio-protective effects.
The fish is a type of freshwater minnow, native to South Asia and a popular aquarium fish.
Hibernation is a physiological condition found in many species that protects them against harsh conditions, such as food scarcity and low environmental temperatures.
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. The researchers believe if astronauts hibernate on their journey, those difficulties may be solved.
The research has been published in the journal MDPI Cells.
Professor Gary Hardiman, researcher from the Institute for Global Food Security (IGFS) at Queen’s University Belfast and senior author, said: “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.
“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.”
To conduct their study, the researchers exposed zebrafish to radiation like what would be experienced on a six-month journey to Mars. The researchers found that this radiation caused signatures of oxidative stress, stress hormone signaling 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 at Queen’s University and co-first author of the research, 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 was funded by a US NASA EPSCoR award and a Department for the Economy (DfE) Research Studentship and was carried out by researchers including Dr. Willian A da Silveira and Ms. Hao Wang from IGFS/School of Biological Sciences (SoBS) at Queen’s University and Dr. Ian Overton from The Patrick G Johnston Centre for Cancer Research (PGJCCR) at Queen’s.
Investigators from the USA included Drs Ludivine Renaud, Tucker Williamson and Sherine SL Chan from The Medical University of South Carolina (MUSC) and Dr. Dongjun Chung from Ohio State University, Columbus.
The full research paper is available here: https://www.mdpi.com/2073-4409/10/4/906.
