The alteration of the smooth muscles of the gastrointestinal tract (GIT) of animals after a long stay in weightlessness was established during experiments carried out by scientists from the Russian People’s Friendship University (RUDN) together with colleagues from the Research Institute of Biology and Experimental Medicine of Russia. the Voronezh State Medical University (VSMU) is named after him. NN Burdenko, March 31, Izvestia reports.
Data on a decrease in the activity of the smooth muscles of the gastrointestinal tract in humans and animals, scientists obtained while studying tissue samples from rodents that were in orbit. The results of the experiments will help specialists better understand how and why changes occur in the body of astronauts during long flights and will help them find methods to combat the harmful effects of weightlessness on the human digestive system.
Director of the Scientific and Educational Resource Center for Innovative Immunophenotyping Technologies, Digital Spatial Profiling and Ultrastructural Analysis at RUDN University, Dmitry Atyakshin, explained the problem that scientists are solving:
“To develop manned flights it is necessary to take into account the factors that affect the health of astronauts. Microgravity conditions affect most of the physiological functions of the body and are capable of causing significant changes in some cases, which is why the attention of most biologists, physiologists and space doctors is focused on them. Smooth muscle tissue actively participates in the development of pathological and adaptive conditions, including the conditions of orbital flight. But despite this, the mechanisms of their sensitivity to weightless conditions remain virtually unexplored.”.
To understand what happens in the body’s gastrointestinal tract under conditions of prolonged exposure to weightlessness, scientists examined the smooth muscles of the fundus of the stomach and the jejunum (the middle section of the small intestine) in rodents that were orbiting in microgravity for several weeks. .
These were mice that completed a 30-day space flight aboard the BION-M No. 1 biosatellite and Mongolian gerbils that spent 12 days in space aboard the Foton-M No. 3 spacecraft.
Scientists have found that spaceflight caused a decrease in the production of α-smooth muscle actin (αSMA), a protein involved in smooth muscle contraction, in rodents. Thus, the stomach muscles of Mongolian gerbils lost 15% of αSMA compared to their counterparts on Earth.
As it was necessary to ensure that weightlessness was to blame for this loss, researchers conducted additional tests that ruled out other causes. Dmitry Atyakshin added his explanations as follows:
“The decrease in intracellular actin production in the muscles of the stomach and jejunum indicates a high gravitational sensitivity of contraction of the hollow digestive organs. This poses new challenges for spatial gastroenterology and advises continuing this area of research. The results obtained should be taken into account to level out the adverse effects of the biological effects of the factors accompanying astronauts during long orbital missions aboard the ISS.”.
According to the head of the laboratory of experimental biological models of the VSMU Research Institute of Experimental Biology and Medicine that bears his name. NN Burdenko Tatyana Samoilenko, cosmonauts many times described to scientists how their digestive system works in orbit. Among the unusual symptoms on Earth, they noted blood filling, impaired evacuation function of the gastrointestinal tract and a number of other unpleasant sensations.
Since scientists in orbit do not have access to internal human tissue, they conduct animal experiments to discover what changes at the molecular level occur in zero gravity. However, researchers still don’t know how astronauts can avoid unpleasant conditions in their gastrointestinal tract.
“Smooth muscle tissue is essentially the lining of the stomach through which all of its contractions occur. The muscles of the arms can be worked out with special exercises, but the muscles of the stomach cannot be stimulated in this way.”, noted Tatyana Samoilenko. — We did more research with animals in space and the same group on Earth. They were created under conditions of altered gravity and fed equally with different types of food. “As a result, we found that the nature of the food does not in any way affect the changes in smooth muscles.”.
Since scientists do not yet see a way to combat these problems in astronauts with special diet or exercise, they are focusing on the possibility of drug therapy.
The downside of the studies was that the scientists could not directly observe the process of tissue changes: they only had access to the animals after they returned from orbit. However, they found that the rodents’ gastrointestinal tract did not return to normal immediately after the flight. Even after a week on Earth, they observed problems with the functioning of the gastrointestinal tract in rodents.
The researchers’ future plans, Tatyana Samoilenko said, include studying the microenvironment of smooth muscle cells to understand what happens during weightlessness in neighboring cells.
The results of RUDN scientists are confirmed by data from experiments carried out on board the ISS. As Boris Afonin, senior researcher at the laboratory of nutrition and gastroentology of the State Scientific Center of the Russian Federation – Institute of Medical and Biological Problems of the Russian Academy of Sciences (SSC RF – Institute of Biomedical Problems of the Academy of Sciences of Russia) That said, these experiments studied changes in the digestive system of astronauts during space flights.
To do this, they used a gastroenterograph, which records the electrical activity of the gastrointestinal tract, that is, specific frequencies of the stomach, duodenum, ileum, jejunum and large intestine.
First, scientists conducted studies with people on Earth, simulating a state of weightlessness, and as a result an increase in the electrical activity of the digestive system was obtained. But similar experiments carried out in space confirmed the results previously obtained in animals: in humans there was a sharp decrease, up to 30%, in the activity of the gastrointestinal tract.
According to Boris Afonin, the problem is that in conditions of weightlessness, food in the body has no weight, that is, there is no gravitational component in the normal functioning of the digestive system.
Source: Rossa Primavera
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