Space Mice Reveal Why Muscles Waste Away In Space

Exposing mice aboard the International Space Station to artificial gravity has revealed the molecular mechanisms behind muscle waste.

AsianScientist (Nov 22, 2021) – With all the excitement over commercial space flight thanks to Elon Musk and Jeff Bezos’ sojourns into space, there’s never been a more appropriate time to imagine what it might be like to float around in space. But have you ever considered what living in space, especially with its reduced gravity, might do to your body?

The effects of space travel on the human body have long been documented, with returning astronauts displaying reduced skeletal muscle mass and strength as a result of long exposure to a low gravity environment.

However, conventional studies investigating the effects of reduced gravity on muscle mass and function usually compare spacefaring subjects, usually mice or rats, to a control group that remains on Earth.

The problem with such a design is that any observed differences between the groups cannot be attributed to gravity alone, as other factors such as space radiation, the microbial environment, lack of convection, and even short-term gravitational changes and shock during the launch and return phases differ between spaceflight and Earth conditions.

To more accurately tease out the effects of gravity, researchers from the University of Tsukuba subjected both experimental and control groups of mice to the same conditions experienced by an astronaut in space, including during launch and landing.

“In humans, spaceflight causes muscle atrophy and can lead to serious medical problems after return to Earth,” said senior author Professor Takahashi Satoru.

“This study was designed based on the critical need to understand the molecular mechanisms through which muscle atrophy occurs in conditions of microgravity and artificial gravity,” he added.

The two groups of six mice each were housed onboard the International Space Station for 35 days. The control group was subjected to artificial gravity (1 g) and the other to microgravity, the low gravity environment astronauts experience on spacecraft. Once the mice successfully returned to Earth, the team compared the effects of the different gravity environments on the mice’s skeletal muscles.

“To understand what was happening inside the muscles and cells at the molecular level, we examined the muscle fibers. Our results show that artificial gravity prevents the changes observed in mice subjected to microgravity, including muscle atrophy and changes in gene expression,” explained Takahashi.

Transcriptional analysis of gene expression in the mice revealed that artificial gravity prevented altered expression of atrophy-related genes. The researchers also identified, for the first time, candidate genes associated with muscular atrophy, such as a gene called Cacng1 that plays a potential role in the atrophy of muscle fiber precursors called myotubes.

The researchers add that their work supports the use of artificial gravity in spaceflight datasets for examining the effects of spaceflight in muscles, furthering the understanding of the mechanisms of muscular atrophy.

The article can be found at: Okada et al. (2021) Transcriptome Analysis of Gravitational Effects on Mouse Skeletal Muscles Under Microgravity and Artificial 1 g Onboard Environment.


Source: University of Tsukuba; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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