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gh WHY CAN IONIZING RADIATION PROLONG LIFE?

Syktyvkar , Institute of Biology, Komi Scienctific Center, Ural Branch, Russian Academy of Sciences
31.10.2008
As a result of human activities, a considerable territory of our planet has turned out to be under additional impact of low-dose chronic radiation exposure. Although such exposure to radiation does not cause the organisms death, it has influence on life span. Why and how? Investigation of this issue has been funded through the grant of the RF President for young Doctors of Science.
Send mail Scientist: Alexy Moskalev, Doctor of Science (Biology), leading research assistant , Syktyvkar

For additional information: amoskalev@ib.komisc.ru
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Low-dose radiation exposure prolongs life span. According to the opinion of Alexy Moskalev, Doctor of Science (Biology), leading research assistant, Institute of Biology, Komi Scienctific Center (Ural Branch, Russian Academy of Sciences), ionizing radiation affects genes that participate in cellular ageing. The conclusion has been made by the researcher based on results of his own investigations and published data.

Billions of cells in the organism undergo attacks of natural ionizing radiation. Practically all cells of the body annually experience at least one event of radiation damage. In the course of evolution, efficient safety methods were to appear inevitably to protect from low radiation doses. No wonder that X-radiation and gamma radiation in low and medium doses prolong life span by 10% to 29% with different laboratory animals (insects, mice and rats). And not only with animals. According to findings of the investigations of British radiologists health and life span for 100 years, since 1897 through 1997, those who chose the profession before 1920 fell ill with cancer more often by 75%, which is due to received doses. However, the death rate not due to cancer was lower in that group by 14%. The individuals who became radiologists after the 1920s were also noted for decrease of non-cancer death rate by 14% and general mortality by 8%. In 1955-1975, their death rate from non-cancer diseases was by 36% lower as compared to the reference group rate. Similar data was obtained by the researchers in examination of employees of the enterprises that have contact with ionizing radiation, or of people living in the territory with increased radioactive background.

Very often this effect is connected by the researchers with decreased death rates from infections and other nonneoplastic pathologies in the first half of life. Indeed, low-dose radiation stimulates immunity and cell division, and switches on other cells defence mechanism. However, according to A.A. Moskalevs opinion, such explanation is insufficient.

Irradiation causes DNA molecules damage and formation of free radicals. Such events result in premature cellular aging and death. However, the first to die are most probably the cells that are most sensitive to stress and unable to restore DNA damages, that is the cells which will grow old quicker. This death does not cause harm to the organism as a whole, because healthy cells soon replace the dead ones. Apparently, the organism reacts in such a way not only to low doses of ionizing radiation, but to external stresses in general.

Probably, stress and radiation in particular exert influence on some stress resistance genes that are responsible for restoration of DNA damages and that increase antioxidant defense, or on the apoptosis genes. Some of these genes are already known to the researchers. Both increase of stress resistance and apoptosis of damaged cells may slow down processes of ageing.

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