BEIJING, Oct 19, 2021 / PRNewswire / – Space travel and exploration will become increasingly common in the future, and astronauts will certainly have to spend more time in space during their missions. It is now known that prolonged exposure to the harsh conditions of the space environment is detrimental to the mind and body. In addition to bone and muscle problems, cardiovascular complications, and immune system malfunctions, staying in space for too long can lead to depression in astronauts. However, the underlying biological mechanisms that cause this remain unclear.
To fill this knowledge gap, a team of scientists led by professors Yongqian Zhang and Yulin Deng from the Beijing Institute of Technology, China, conducted a study using rats as an animal model. Unlike previous studies, which mainly focused on the effects of simulated microgravity, the researchers exposed the rats to other intricacies of an extreme and complex space environment. This included a combination of microgravity, noise, isolation and changes in the circadian rhythm over short light-dark cycles. In this way, the scientists ensured that subsequent behavioral experiments and protein expression analyzes more accurately reflect the effects that prolonged exposure to space environments could have on astronauts. The study was published online in Space: Science & Technology At May 27, 2021.
To confirm depression in the rats exposed to the simulated complex space environment (SCSE), the team first performed three different experiments: sucrose preference tests, forced swim tests, and field tests. These were used to quantify loss of appetite, despair and motivation. As expected, the results of the tests taken together showed depression-like behavior in the rats exposed to the SCSE but not in the control group.
Then the scientists went straight to the heart of the problem. After killing the animals painlessly, they took tissue samples from the hippocampus, a major part of the brain that is very prone to long-term stress and has been linked to depression. The team performed two techniques based on mass spectrometry – quantitative proteomics and monitoring of multiple reactions – to create an accurate profile of the cell membrane proteins that were differently expressed in SCSE rats compared to the control group.
The results of these analyzes provided much insight into which proteins and biological functions are affected by exposure to space environments. “We found that the development of the nervous system can be disturbed under SCSE, especially the formation of synapses and the regeneration of neurons,“explains Professor Zhang,”In addition, we found down-regulated proteins involved in synaptic transmission and synaptic vesicular transport.”
Overall, this study will be critical to the development of preventive drugs and interventions for astronauts in the future, Professor Deng concludes.The differentially expressed proteins we have identified will be used as biomarkers for future research and could provide helpful clues for formulating strategies to maintain the mental and physical health of astronauts during missions.“Hopefully science will let us find ways to keep space travel from burdening the mind and body of astronauts.
Original work title: Deep Membrane Proteome Profiling of Rat Hippocampus in Simulated Complex Space Environment by SWATH
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