Are Space Travelling Mice Returning With Liver Damage?

With a manned mission to Mars planned for some time in the 2030s — the long term effects of micro gravity on the human body are something NASA has to give serious consideration to.

A recent study has looked at the effects of space flight on one of the bodies main organ’s — the liver — and found some potentially damaging effects. Take a look at the effects of space travel on the body and how mice are helping in man’s quest to visit Mars.

Physiology in space

With a mission to Mars taking several years to complete, the effects on the human body will be significant. Stress will be one of the factors associated with extended space travel — the isolation and relatively confined spaces are influences that can be explored on earth — but how the astronauts react could be harder to predict.

Another factor — that is difficult to assess on Earth — is the effect of living in a micro gravity environment for an extended period. The physiological effects of spaceflight have been studied on astronauts and animals — with most of the focus on bone, muscle, cardiovascular and the effects on brain function.

For example, muscle fibres shrink in reduced gravity environments, leading to a reduction in muscle mass and strength. The effect is to make astronauts weaker during space flights — even on flights of less than 14 days on the Shuttle. To mitigate the effects of muscle reduction, astronauts on the International Space Station have to exercise regularly.

When the muscle strength reduction is compounded by a reduction in brain function — for example, a reduced sensory motor capability — you can see that an astronaut’s ability to function can be severely impaired during extended spells in a micro gravity environment. With known issues in bone and cardiovascular systems for astronauts — it is easy to see how a good knowledge of the physiological effects is necessary for extended space missions.

Don’t forget the liver — a key organ for our metabolism

Another of the body’s organs that needs investigating is the liver. The liver is a key organ — cleaning blood, helping digestion and storing energy. A recent study published in PLOS One — Spaceflight Activates Lipotoxic Pathways in Mouse Liver — has found that even on a short flight, there might be early signs of liver damage in mice, when compared to controls that remained on Earth.

The mice spent 13 days aboard the last Shuttle mission before their livers were analysed. The team found increased fat storage in the livers and changes in the fat metabolism pathways — similar to early indicators of fibrosis seen in humans, a type of liver disease. The analysis of liver tissue is discussed in this article, A Multi-Platform Approach for Metabolomic Analysis of Human Liver Tissues.

Although it’s too early to say what the long term effects of microgravity might be on a human liver, the study is a reminder that getting people to Mars is not just a complex technological effort.