A Current Overview of the Biological Effects of Combined Space Environmental Factors in Mammals

Abstract

Distinct from Earth’s environment, space environmental factors mainly include space radiation, microgravity, hypomagnetic field, and disrupted light/dark cycles that cause physiological changes in astronauts. Numerous studies have demonstrated that space environmental factors can lead to muscle atrophy, bone loss, carcinogenesis, immune disorders, vascular function and cognitive impairment. Most current ground-based studies focused on single environmental factor biological effects. To promote manned space exploration, a better understanding of the biological effects of the spaceflight environment is necessary. This paper summarizes the latest research progress of the combined biological effects of double or multiple space environmental factors on mammalian cells, and discusses their possible molecular mechanisms, with the hope of providing a scientific theoretical basis to develop appropriate countermeasures for astronauts.

Hepatology in space: Effects of spaceflight and simulated microgravity on the liver

“…More than 500 astronauts have been sent into space to conduct exploration missions thus far. 1 This number is expected to increase at a high pace in the next decades given the rise of touristic space human beings seem to confirm the metabolic inflexibility with induction of diabetes mellitus and non-alcoholic fatty liver disease as seen in experimental animals subjected to microgravity. 42,43 These observations warrant appropriate measures to counteract pathogenesis, especially in view of long-term space missions.…”

“…More than 500 astronauts have been sent into space to conduct exploration missions thus far 1 . This number is expected to increase at a high pace in the next decades given the rise of touristic space travel.…”

“…Most of these conditions are hardly, if at all, compatible with life on Earth, including radiation and microgravity. Microgravity in particular is gaining increasing attention, as weightlessness not only leads to the deterioration of bone and muscle, but also modifies body fluid distribution, the immuno‐haematological system, cardiovascular functioning and the neurovestibular system 1,2 . Effects of microgravity on metabolically highly active organs have been poorly documented thus far.…”

The Protective Role of Neurogenetic Components in Reducing Stress-Related Effects during Spaceflights: Evidence from the Age-Related Positive Memory Approach

“…Additionally, studies on space stressors are increasingly focusing on how different stressors interact with one another, particularly MG and IR. As described in the next paragraphs, ground-based research using animal models [ 79 ] shows that IRs have negative effects on the body, specifically the skeletal system, visual system, cardiovascular system, stem cells, and central nervous system (CNS), as well as negative effects on a variety of cognitive abilities, including memory. These findings indicate that our assumption about the importance of detecting a positive memory-based genetic profile to adapt to the space environment must take into account how IR may impact, alone or in combination with MG, a series of physiological and psychological mechanisms that may render the positivity bias less likely to occur during a mission.…”

Impacts of radiation exposure, hindlimb unloading, and recovery on murine skeletal muscle cell telomere length

“…However, studies on telomere length following radiation exposure, specifically focusing on the muscle compartment, are nonexistent. Most importantly, the combined effect of weightlessness-induced skeletal muscle atrophy and cosmic radiation exposure reported during spaceflight 58 led us to query whether these factors can contribute to changes in telomere dynamics in myogenic cells in a ground-based mouse model.…”