The total of 13 days in space enough to cause profound changes in the structure of the eye and the expression of genes, the study, which was led by scientists from the Space Center Lyndon Jones from Houston (USA). In the study, researchers studied how low gravity, cosmic radiation and oxidation stress affect the mice. In addition, this is the first study that has examined the expression of genes involved in the work of the eye, as well as the behavior of the cells after space flight. The scientists found changes in the expression of genes that help cells to cope with oxidation stress in the retina that occurs, probably due to radiation exposure. These changes are partially reversible after returning to Earth. Also, a marked change of optic nerves, coupled with mechanical injuries that are not restored. In addition, the researchers saw a change in the expression of the DNA of genes for repair damage, and in the pathways that help the body break down damaged cells.Researchers studying astronaut since 2001, noted that those at increased risk of developing eye problems, such as premature age-related macular degeneration. Experts suspect that the reason for that – the low gravity and increased exposure to solar radiation. In November 2011, a study of 7 astronauts found that all of them have vision problems, after having spent at least 6 months in space. Doctors have seen a flattening of the back of the eyeball, the creases in the choroid the vascular tissue behind the retin, excess fluid and swelling of the optic nerve. High-energy radiation from the sun can cause unpleasant extremely destructive chemical reactions in the cells, referred to as oxidation stress. The magnetic field of the Earth and the atmosphere reflects or absorbs most of the radiation, and does it much better than a thin metal coating hulls of spacecraft and the International Space Station.
Eye injuries not only cause a number of problems in astronauts after returning to Earth, the problem may prevent future space missions. Especially dangerous it can be to long-term missions, such as flying to Mars 12-16 months or to the satellites of Jupiter about two years. If scientists can prove that the cause of damage to the eyes is still the effects of radiation and low gravity, then one solution would be the construction of space vehicles with a higher level of protection of housing. Can help and installation of centrifugal devices to simulate gravity, which is described by the writer Arthur C. Clarke and director Stanley Kubrick showed in the movie Space Odyssey 2001. To determine the effects of radiation exposure to the eyes, the researchers examined the gene expression of the retina of mice on the 1st, 5th and 7th day after the 13-day journey aboard the space shuttle Discovery STS-133. The researchers also examined the eyes and surrounding tissue, analyzed their structure and form, to understand how they are affected by low gravity. After the return to Earth of mice, the researchers found in their retinas traces of oxidation stress. But the expression of six genes involved in oxidation stress, to be normalized on the seventh day of life on earth. Indicator of oxidation stress in the cornea kept at a high level the day after returning from orbit mice, but returned to normal on the seventh day.
This demonstrates that oxidative stress can be controlled, it is reversible. However, scientists fear making long-term conclusions: perhaps the results will be different after a long stay in orbit. Also mice visited orbit, the researchers found increased content of beta-amyloid protein in the optic nerves, and this increase is maintained and after seven days in the world. Beta-amyloid is associated with brain injuries in humans was not detected in the mice in the control group who were not Earth. Researchers have found an increase in the number of glial cells, which respond to the optic nerve injury mice were in space. However, it is not known whether the content of beta-amyloid and glial cells due to the impact of the low gravity or travel into orbit or orbit. Scientists have also discovered that mice astronauts increased levels of caspase-3 in the retinal pigment epithelium caspase-3 enzyme helps the immune system to destroy damaged cells. Such anomalies epithelium normally associated with the development of age-related macular degeneration. Scientists point to the fact that while their study are preliminary in nature – have to study the long-term impact on more experimental.